Author Topic: DT/SW5 Engines  (Read 5666 times)

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Offline Buzzie

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DT/SW5 Engines
« on: 29 Dec 2018 at 11:14 »
Hi, I've just registered on the forum and,  as suggested, thought I should say hello.

My name is Douglas McLay, my Username should have been Buzzie, but my fingers got it wrong when I registered :( ! I live near Burton on Trent.

I've joined because I own two DT/SW5 engines, or rather the makings of two. I've had one for about 20 years, and bought the other on Fleabay a few months ago. The engine numbers are EL627 and EL781.

I am now trying to build one engine up to running condition. Although I have quite a lot of experience building post war car engines for racing, I can see there is a lot I need to learn for this project. There are a lot of unfamiliar techniques and technologies in these vintage engines. My plan is to build the first engine using the parts I have, and using what I learn to eventually build the second engine modified to make it a reliable competition unit.

The first engine (627) has had the bottom end and cylinders fettled and assembled by a reputable bike racing engine specialist. I have a few resources I've dug up over the years, done quite a lot of research on line and looked at complete engines in museums etc. I and can recognise most of the engine parts, but I still have a plethora of questions I need to answer before I can start assembly and the road to getting it running!!

I wont attempt to list my worries, it would take all night and you'd all be bored before getting very far! I am hoping that some people with first hand knowledge of working of theses engines may come to my aid, and in conversation help me understand my engines and how to get at least one running.....

However one of my biggest areas of ignorance is lubrication. I really cant understand from the snippets of information how it operates and how each component is lubricated. Also I realise that originally it would have used Castrol R, I wonder if these days modern  fully synthetic oils would be a better bet?

Thank you for getting this far, and I'm hoping that some of you can help me towards my goal.....


Offline eddie

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Re: DT/SW5 Engines
« Reply #1 on: 29 Dec 2018 at 15:54 »
From the photo you have posted, your engines look to be 1929 long stroke 500's (DT5's) with the smaller airbox. If this is the case, they will be fitted with mechanical oil pumps. Unfortunately, when Mr Douglas updated them from the 1928 model, he retained the hand pump in the tank, so the oil circuit is rather complicated as it allows the hand pump to by pass the mechanical pump. This is achieved by fitting a banjo bolt with a non return valve into the oil gallery in the timing chest. On our vintage sprint bikes, we did away with this bypass to prevent the chance of the oil returning to the feed side of the pump and starving the big ends, etc., should the valve jam open. The oil pump itself is a 2 stage affair, with the first stage drawing oil from the tank and sending it to the drip feed sight glass (any excess passing through a pressure relief valve back to the feed side of the pump). The metred oil is then drawn through the 2nd stage of the pump and sent direct (via a quill) to the crankshaft - from where it sprays around to lubricate all other moving parts except the valve gear. The rockers are fed with oil from the pots on the top of the rocker spindles - just the valve stems need oiling with a can before each day's run.
  The 1928 engines had the oil piped direct from the pump in the tank to the quill on the end of the crankshaft - the pump in the tank being operated via a cable and a  lever on the LH handlebar.

  Regards,
                 Eddie.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #2 on: 29 Dec 2018 at 21:28 »
Hi Eddie, thanks for your very helpful post.

My engines both came with mechanical oil pumps, and some unions, but I haven't yet looked to see if one has a non return valve in it. I had found out that the pump mounts on the airbox, and using my air line have seen how the internal oil ways are connected. I have shown these in the attached photos and sketch. I'm assuming that the if the by pass is blocked off, as you do, you dont need the hand pump on the tank?

I have a (non illustrated) original parts list for the "Dirt Track Model K/29", also pictured. It doesn't show any mechanical oil pumps, which was one thing that was confusing me. I guess it must be from a 1928 or earlier engine.

There is also no mention of the quill, and I don't appear to have any with either of my engines. I assume it screws into the end of the crankshaft and passes through the felt seals in the crank and air box? To be honest I have no idea what one would look like, but I can't find anything which could screw into the crank!

I also attach a sketch of my idea of how it works, which is:

Oil is gravity fed from the tank to the inlet on the side of the air box to stage one of the pump, and then out into the regulator through the air box casting,

The oil drips out of the regulator at the set rate, through the air box casting and into stage 2 of the pump, when it is then pumped into the crankshaft.

Finally do you run your sprint bike on Castrol R and ethanol?

best wishes,
Douglas


Offline Doug

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Re: DT/SW5 Engines
« Reply #3 on: 30 Dec 2018 at 04:28 »
Doug,

Mid to late 1929 they switched from the tall airbox (part #10520 ) to the small airbox (#11759). So you won't see the small airbox and oil pump in the K29 list.

"A" in the following image is the non-return valve that Eddie spoke of. it is much like a banjo bolt (intersecting the side gallery as it does), but has a check ball and spring in the nose.



"B" is the cap for the crankshaft oil quill.

The oil quill (called a Oil Feed Nipple in the parts list) resides in the 9/16 inch bore in the airbox, under that cap. The following is the components.



The spring (#8840) is not shown in the illustration, but is 0.48 o.d., about 1-1/4 long, 1/4 pitch, 4-1/2 active coils, 0.040 dia. wire.  It fits in a recess in the cap in order to gain additional working length.

-Doug

Offline eddie

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Re: DT/SW5 Engines
« Reply #4 on: 30 Dec 2018 at 07:25 »
Hi Douglas,
                  Our sprint engines run on Methanol fuel and Castrol 'M' oil. (Castrol 'M' is a vegetable oil, very much like 'R'). The engines are set up with high compression pistons and larger than standard cams. The valves and guides are a mixture of Norton Commando and Triumph Bonneville parts. Other than that, my engines are pretty much standard. My best time on a standing start ¼ mile is 12.78 secs with a terminal speed of 103mph. Other riders have sacrificed some originality in their motors to gain better performance - the best recorded time is about 12.16 secs with a terminal in excess of 110mph.
  The oil quill is brass and is just inserted into the end of the crank - the spring that Doug mentioned keeps it in place and also squeezes the leather seal to prevent oil escaping.

  Regards,
                Eddie.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #5 on: 30 Dec 2018 at 20:47 »
Doug and Eddie,

thanks very much for your comments. I think am slowly getting to understand the lubrication system!

I've looked again at the parts I have, and the good news is I'm pretty sure I've found a quill! I haven't measured it yet, but it looks pretty promising. I've also found two banjo bolts, I wonder if one of them is the bypass valve? However if I've understood correctly I won't need one if I just plug the port which normally carries the feed from the manual pump into the airbox casting. "A" in the picture below

I was looking for a quill that screwed into the crank, because both of mine are internally threaded. But when you told me that the quill just pushed into the crank I wondered if the threads were in effect a scroll to throw the oil up into the inside of the crank.

One thing that I don't understand is what happens to the oil once it has splash lubricated the engine and falls into the crankcase. Is it a total loss system with oil leaking out all over the place, or does it need to be periodically drained off from the crank case?

Those performance figures are very impressive Eddie! I have a very long way to go before I could be in that league. My engines are eventually destined to be in a 500cc racing car built in 1947 with a DT5 engine installed. It wasn't competitive back in the day, but I would like to recreate it and use it for historical interest.

The engine I am building looks like it has Douglas high compression domed pistons installed, but I haven't yet measured the combustion chamber volumes nor the volume displaced by the piston crown to estimate the compression ratio. I also need to dismantle the carbs to see if they are jetted for ethanol......

Best wishes
Douglas
« Last Edit: 31 Dec 2018 at 11:20 by Buzzie »

Offline Doug

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Re: DT/SW5 Engines
« Reply #6 on: 30 Dec 2018 at 21:16 »
Douglas,

Yes, you found the quill. In that same picture is the non-return valve. The slotted brass insert in the tip un-threads to release the check ball and spring. The other banjo bolt in the same view is really a banjo bolt, and is for the oil supply feed to the front wall of the airbox.

The conical seat of the oil quill runs against a bolt that screws into the end of the crankshaft. This bolt has a left hand thread. It retains the engine pinion, and has a conical seat for the quill to seal against. Usually the engine pinon is fitted so tight that one wonders why they bothered with a bolt! The quill floats in the airbox (not the crankshaft), pushed against the end of the crank by the spring.

The oiling system is total loss, whether a mechanical pump is fitted or not. Hence the rather small an metered supply. Any unused oil has to be burned or leak out; which usually is not a problem! Oil will pool in the timing chest to a level to wet the timing gear train. Excess flows into the crankcase chamber proper via a hole in the rear wall. A pool of oil remains in the bottom of the crankcase. This is struck by the conrods and the ribs on the center web of the crankshaft to splash oil about. There is a rib in the bottom of the crankcase which is often erroneously removed. The purpose of the rib is to create two pools of oil so that each is only struck once per revolution of the crankshaft. If it were one common pool, it would be struck twice per revolution, and at higher revolutions there might be insufficient tome for the oil to flow back into the path of the crankshaft. Or that seemed to be the theory, anyway.

Despite this, there seems to be a lack of oil getting splashed about as lubrication of the cam lobes and tappet faces always seems to have been marginal.

The early Iota cars would have be much more competitive in the 500cc class when the Dougie engines were secretly fitted with the 600 or 750cc barrels on the DT crankcases!

-Doug
« Last Edit: 31 Dec 2018 at 06:06 by Doug »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #7 on: 31 Dec 2018 at 11:08 »
Thank you Doug for your latest words of wisdom!

I have three cranks and none of them had the left handed bolt in. However one of them had the remains of a felt pad/seal in it. The good news is that I rummaged around in my tray of nuts, bolts, unions etc and came up with two of the bolts! I've put the crank, bolt quill etc together, and blown through the quill and got air out of oil oil feeds on the big end journals.

I'm interested in your remarks about lubrication of the camshaft and tappets. All my parts in this area show signs of wear. I'm wondering if hand lubrication between runs through the top of the engine would help.

I have no idea what the felt bit is, or indeed whether it should have been in there. There was no sign of one in the other two cranks. The unbuiltup crank case has the rib down the middle, and as far as I can see the built up one does too. Whilst thinking about the crank cases are sealed together with a gasket. The info I have is ambiguous. The engines I've seen in the motorcycle museum don't seem to have a gasket fitted, but its not easy to be sure. My only experience is with more modern Ducati engines, which don't have a gasket but are sealed with a special sealer

I have also dismantled the by pass valve, and its all present and correct. I can see why Eddie worries about it sticking. I had to blow compressed air into it to unseat the ball after soaking it in WD40. I am assuming that if I don't use a manual pump I wont infact need it.

My mind is now turning to the type of oil to use. I was considering using a modern synthetic oil, but think I should stick to a vegetable oil. Would R30 be the best one to choose? I will obviously need to decide before I start final assembly.

I attach a picture of a spare piston I have, which I think is a Douglas High Compression one. Identical pistons are in the built up bottom end. The other engine has Douglas flat top pistons, and I have some spare new BSA flat top pistons which I have read are a suitable replacement.

Best wishes
Douglas
 
« Last Edit: 31 Dec 2018 at 11:23 by Buzzie »

Offline Doug

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Re: DT/SW5 Engines
« Reply #8 on: 31 Dec 2018 at 20:15 »
Douglas,

I have not heard of a felt pad being used between the oil quill and the crankshaft. Sounds like a recipe for disaster if bits of the pad broke off and plugged the internal galleries of the crankshaft. Sure it is not the leather gland for the rear of the quill? All the ones I have seen just used the brass (or bronze?) quill against the steel crankshaft bolt. The only difference is for the 1934-35 ohv models the check valve was moved to the tip of the quill; however the oil circuit was substantially different and they were a full recirculating system. No hand pump either!

Douglas progressively made the cam lobes and tappet faces wider from the original 1921 Sports model up to the era of the DT. Even so, one sees horrendously worn cams and tappets. I've had cams re-profiled and manufacture new tappets due to the lack of good used originals being available. I am not sure if the problem is oil not getting thrown up onto the cam in sufficient quantities or the oil not sticking. I don't think the Douglas splash system was all that effective, particularly as they got away from introducing oil at the base of the front cylinder. A few models (like the TT models) had a window frame at the base of the engine that eliminated any chance of having any pool of oil for the crankshaft to strike. The castor based oils were to my understanding used for two salient properties. Not being readily miscible in petrol (key for early rotary aero engines) and not being as prone to break down under extreme heat when compared to the petroleum based oils of the day. The later seems to have been solved by modern oil. The late Phil Manzano (who knew a thing or two about Kawasaki and Douglas sprinters) reckoned the best solution was to use fully synthetic oil. However there was problem with the synthetic oil not allowing new piston rings to bed in, so the initial break in period was done with regular oil.

As a total loss system, beyond the points noted above the type of oil is not so critical as it does not spend very much time inside the engine! Originally intended for mono-grade, I have used multi-grade in a pinch. It is sort of a waste of technology as the engine is (presumably) getting a constant supply of fresh oil. There is not quite the need for temperature modifying polymer chains in the oil. The big end rollers will chew up the polymer chains eventually and turn it into mono-grade, but again it is constantly getting a new supply. But mono-grade is harder to get whereas multi-grade you can pick up anywhere. Even more so the detergents found in modern oils; sort of pointless in a non-recirculating and unfiltered system. The only danger there is putting detergent oil in a engine that already has sludge deposits in it. However on a fresh rebuilt that is a moot point and detergent is not really a factor. The only negative is the volume occupied by the detergents and other modifiers is less volume given over to actual lubricant. Hence things like turbine oil being pretty much 100% oil and nil additives. But it is a toss up between the anti-scuff additives in modern oil, vs. that extra few percent pure mono-grade, non-detergent oils would provide, regarding tappet wear. I plan on using synthetic automotive oil.

I have not heard of anyone going to the trouble of designing an oiling system to manually lube the camshaft between runs. I suppose one could make a customized exhaust lifter fulcrum plate that had oiling points. Most of the wear seen being attributed to a long and abused life that the majority of DT engines have by now accumulated. Nowadays they are not as used or abused quite as much, and get better maintenance. I have heard mention that the ultimate Works TT developments of the early to mid-thirties descendants of the DT had an oil feed to the end of the camshaft; presumably the latter being drilled for oil delivery to the individual lobes. I have not seen an example to verify, but see how it could have been relatively easy for them to have implemented.

The crankcase joint was intended to have a paper gasket. These are the "Joint Paper Washer"(s) in the spares list though I do not know which number is assigned to which gasket. They list four, and only three segments are needed for the crankcase halves. The fourth is probably the timing chest gasket. The cylinder base and exhaust lift fulcrum plate gaskets are listed elsewhere. The gasket is factored into the machining of the timing half (if I remember correctly) and dimensions show it was intended to be a 0.006" thick. Without a gasket the case tends to nip up too tightly on the one tappet guide that spans the joint. Also if you have the exhaust lifter mechanism intact, the bush that passes through the case can cause the joint faces from closing up locally if the gasket is omitted. The cylinder spigot usually has enough slop that it is not a problem, but obviously should be checked.

The pistons varied depending on the length of the cylinder barrel (there were at least three factory lengths) and the compression ration/fuel used. The high domed pistons are probably what was used back in the dirt track days when using 50-50 petrol-benzol. The flat top look like what you see in the road going variants of the DT, that used straight petrol. Compression ratio info is scarce, but I have come across the following in factory letters: 10:1 (maximum) on alcohol, 7:1 for petrol-benzol, R.D.1 (?) fuel 9:1. Presumably regular petrol ratios were around 6:1, but that is even harder to find info on than the racing jobs! I made 6-1/4:1 pistons that were slightly domed for my road-going 1934 ohv Dougie and it seemed fine on standard pump gas; possibly would have gone even a little higher. This was back in the late eighties and early nineties before ethanol, however! For my SW5 more recently I converted some Rudge pistons, but I didn't bother to work out the ratio as they only had a modest dome dome like the pistons I had cast. Hopefully that will be on the road in 2019 and we shall see how it does. Occasionally you will see H.C. stamped on DT crankcases by or opposite the serial number. It is believed this indicated where the factory had fitted a motor with high compression pistons. Of course between then and now anything and everything could have been altered! I have also heard of a little bit of nitro being 'tipped in', but the only indicative evidence I have seen is the piston crown being reduced to a bunch of crumbs the size of raisins!

-Doug



[fix typos. 01Jan19 -Doug]
« Last Edit: 01 Jan 2019 at 20:59 by Doug »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #9 on: 01 Jan 2019 at 20:22 »
I was thinking that about the felt as I was trying to get it out of the crank. Interestingly that crank, which didn't come with either of my engines had felt in it, and one of my crank cases has a felt washer/seal pressed in the hole through which the quill passes.

I had am not surprised that there were gaskets fitted between the crank cases. Making those should be fairly straightforward when I get my hands on some 6 thou gasket paper. I realised that those 6 thou could be critical to the correct dimensioning of the crank case. Whilst on the topic of gaskets Im assuming that the head gaskets are fairly conventional, although I am a bit curious of why there are grooves machined in the head faces. At first I thought they were for Wills rings to be fitted, but I don't think they were around in 1929.

I hadn't anything as sophisticated as you describe for oiling the camshaft and cam followers. I was thinking of taking the magneto off, removing the circular cover underneath and squirting oil about with an oil can!. I'm very interested in your remarks about synthetic oils. I know they have some pretty good scuff resisting qualities and work well when very hot. But I suppose the oil in Douglas engines is only there as a lubricant and doesnt contribute to engine cooling. I think I will talk to some of the specialist oil companies here in the UK about it, with a view to using a synthetic oil in my engine.

I think I need to do some work on measuring parts and calculating compression ratios. I've seen the letter you refer to and use it as a yard stick about what to expect. My plan is to use ethanol if possible, it is widely used in 500cc car racing, and the literature is clear that Buzzie was run on ethanol. My engines both have steel ring/plates fitted under the cylinder castings. I recall reading somewhere that these were used as a means of adjusting compression ratio. Obviously I can factor in the effect of these into options for setting the compression ratio to a suitable value.

I am aware that a lot of the parts I have are quite worn. My approach will be to ensure that the rotating and reciprocating parts do not have excessive play to reduce the chances of catastrophic failure, but to use the best of my existing parts elsewhere and accept a loss of performance. My idea is this would allow me to understand how the engine goes together, get a feel for the engine and make more informed decisions about what new and or modified parts to fit in the second engine. I don't really have any idea how fast the engines revved to in the day, or where the maximum power was achieved. I expect a more modest rev limit on my first engine to preserve it in one piece.

In any event there were not many 500s fitted with Duggie engines, and those that were soon replaced them because they were under powered and unreliable. So Im not undertaking this work with a view to winning laurels on the racetrack! Buzzies chassis was as uncompetitive as its engine, so its just a bit of historical fun.

Best wishes

Douglas

Offline Doug

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Re: DT/SW5 Engines
« Reply #10 on: 02 Jan 2019 at 06:19 »
Douglas,

Oil that does not break down at elevated temperature is not just for engines that overall run hot, but is critical at localized hot spots like areas that experience scuffing or high pressures. Some of the synthetics are so good at this, that is why inhibit newly rebuild engines from bedding in correctly.

Yes, metal plates under the barrels can be used to adjust the compression, restore piston to head clearance, and restore cylinders that have had too much machined off the base flange!

There are some new parts for the DT/SW5 available see, ahem, my adverts posted here on the DMF. Tappets, valves, special taps, and eventually I'll post an advert for some of the hardware Douglas used with their proprietary threads.

I have not see information on how far the rpm can be pushed. I think in the old days it was 'until the power fell off' (probably due to valve float) or it went "bang!" I know various folk in the past have quoted numbers; some of which seemed ludicrous. Some of the 'examples' I can think of were on machines that did not have a tachometer fitted anyway, so it was pure speculation and a generous dose of exaggeration.

The Achilles heel of the Dougie is the crankshaft. Once they start to go bad there is not a lot of scope for remedial action. The heat treat specification was quite violent resulting in a abrupt transition between the core and case; leading to brinelling. If the surfaces have not started to break up, marginal oiling could have cause partial seizure of the cage. If it does not cause the cage to weld it often causes the cage to rack, which will induce the conrod to thread it way sideways against the center web or the counterweight. Usually the center web because that is more expensive to repair! Always check the cages on an optical comparator (shadow caster, profile comparator) to make sure the are square. Finding cages that are not worn out and are keeping the rollers square is starting to be a problem as well. Do everything you can to preserve the life of the crankshaft, as they are extremely difficult to find replacements for and extremely expensive to make new.

The Iota Stromboli had a Dougie engine in it. When it was purchased by the current owner for the rare Dougie 4-speed gearbox and the Dougie engine, it was found to be fitted with 750cc barrels. Don't know if it raced that way, or how successful it was (or was not).

-Doug



Offline Doug

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Re: DT/SW5 Engines
« Reply #11 on: 02 Jan 2019 at 13:12 »
The cylinder head gaskets were a solid copper wire of diamond cross section that matched the profile of the groove in the cylinder and head.

-Doug

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #12 on: 02 Jan 2019 at 22:26 »
Hi Doug

That information about the head gasket is a bit worrying! I dont imagine that diamond cross section copper wire of the right dimension is easy to find..... What are the solutions that people have used in its absence? Can you use modern head gasket material to make a serviceable gasket?

I found the discussion about wear etc in the crank and big end bearings very interesting. I will need to re read it all carefully a few more  times before re assembling my engine. I don't think any of my cranks are in decent condition, although the best one is probably in the half rebuilt engine, and I shouldn't dismantle that until I'm ready. I had a crank machined out of a solid billet of decent quality steel for an MG engine I raced with in the eighties. It was very successful, but even in those days horrendously expensive! I guess you would have the basic crank made and use original counterweights?

Here is what is said about Stromboli on the 500 Owners Club website :

Adrian Butler (secretary of the original CAPA) and Bruce Mardon's Iota based car was the first to be completed. It used a Douglas flat twin engine, Morgan style front suspension and swing axle and leaf spring arrangement at the rear. The pair attended the "White Hart" meeting in May 1947, then June Shelsley, Gransden Lodge in July where they failed to start and Prescott in August where Butler took second fastest time to Brandon's Cooper. Shelsley in September brought a seventh for Mardon and they finished the year with a trip to Towcester in October. We have no photos of Stromboli wearing clothes so perhaps the pair realised that this engine/chassis combination would not be a match for the Coopers and retired her. Adrian continued to play a part as editor of Iota until the end of 1949

Stromboli was a contemporary of Buzzie, but more successful! Buzzies chassis was as uncompetitive as its engine! Ironically its builder replaced Buzzie with an Iota! However its difficult to imagine either being on a par with a Cooper fitted with a Norton or JAP engine!

It wouldnt surprise me at all if one or both cars had a 750cc Duggie unit fitted. Buzzies owner had questionable morals as he later resurfaced being involved in Lord Brocketts Ferrari scandal !!!!! I also suspect that many of these engines may have been pretty worn themselves. Buzzie was built in three weeks and cost £35. I doubt that would involve an engine build or buying a known "good" engine. Buzzie had a four speed Norton gearbox.

best wishes
Douglas

I understand exactly what you were saying about the engine revs. I instinctively thought that 5000 RPM would be a good conservative limit, but then read in various places of much higher speeds. Its difficult to get excited about wringing an extra few BHP out of the engine for it to still be very uncompetitive. What sort of speeds do you run your engines at. Or maybe without a tachometer thats not really how you think about it.


Offline Doug

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Re: DT/SW5 Engines
« Reply #13 on: 03 Jan 2019 at 03:44 »
Douglas,

If you can get a set of the original rings they can be annealed and reused almost infinity. There is really no crush to them, they just conform to localized irregularities. Once the head touches the cylinder however, they are no longer clamped or able to seal. I don't know what others have done, but I make them out of square copper armature wire. The type used in very large motors of 50hp and upwards.




I had concocted a fallback plan of rolling the wire onto edge and into the diamond profile, but found that it sealed just as well laying flat in the diamond groove and bearing on the corners. I suppose round wire could be used, but I figured the square wire would be easier to file true at the weld joint. The rings were made slightly smaller than required and the joint welded using a tungsten inert gas torch. Filler wire was common domestic electrical copper wire used in wiring up the house. After the joint was filled and the ring annealed, it was pressed over a mandrel with a gradual taper to expand it to the correct size and make it nice and circular. It was impossible to roll the rings up and form the joint with the circular accuracy desired. Stretching it twenty thou to make it round worked better than expected. Had it been pursued to make them diamond shaped, the plan was a similar mandrel with the last bit on a 45 degree angle to get the ring to roll on edge; with perhaps a complimentary angle of the pusher sleeve.

About 10-15 years ago there was a batch of a dozen billet DT crankshafts made; commissioned by the late Ken Hall. At that time they were selling for around a thousand pounds; and sold out. On approaching the manufacturer (Fardon or one of the other manufactures of F1 replacement crankshafts) at that time quoted a further supply would be more like 1200 a piece, and the minimum order would be two dozen! Needless to say that was a bit more than any enterprising individual wanted to bankroll and with the immediate market needs satisfied the prospects of getting the investment back appeared to be a long term commitment. I figured out a Hirth joint design (see below) that I reckoned had promise and didn't require a jigbore machine, but then I took the simple way out and bought one of the billet cranks!



If you have not already seen it, a photo-description of the crankshaft assembly can be found in this post:

https://www.douglasmotorcycles.net/index.php?topic=402.msg1191#msg1191

Though off topic (the 500cc cars would make an excellent post of their own, hint, hint) here is a photo I found on the internet of Stromboli at the 2014 Bristol Cavalcade. I did not attend, so if anyone has better photos of it I sure would like to see them. I saw it many years ago it before it was tidied up an can concur that the build quality was rather grim!



-Doug





« Last Edit: 03 Jan 2019 at 04:15 by Doug »

Offline Doug

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Re: DT/SW5 Engines
« Reply #14 on: 03 Jan 2019 at 04:12 »
Addendum... I don't have a tachometer fitted to any of my Dougies, and they are intended for road use anyway. There is no venue or class for Sprinting them here in the USA like the vintage sprinting sub-class of the VMCC in the UK to warrant building a sprinter. It is either vintage road racing, or nothing. However if there are enough bits left over to build a quick roadster model... Perhaps some of the Sprinters in the UK have tachos fitted. That said, I always thought 5000 to 5,500 was probably the original maximum. Some of the alternate cam timings used in bikes like the Len-Cole sprinter sacrificed the stock low-end grunt of the DT factory timings to get the engine to breath better at elevated rpm. Which is why some of those cams timings made for excellent cams in the road going models. But what that elevated rpm range was I do not know. The use of BSA and Triumph valves and keepers play towards that as they are smaller stem and have less inertia than the stock components. In a heavier car (even a small car) I think torque would be an advantage over revs.

I did dig through the records and fond a report 1932 from C.T. Atkins back to the factory they were getting 34.4hp out of a Works short stoke engine at 6000rpm, and the prior long stroke did a best of about 30hp at 5000rpm. This was for events at Brooklands like the Holiday Cup, Wakefield Cup, Reynolds, Cup, etc., not dirt track racing. It is a little confusing as elsewhere in the same report there is mention of a 'square engine' (the 68 x 68 mm short stoke) with new heads, magnesium (alloy?) pistons, and cam that put out a repeatable 39hp on the dyno. This seems too big a jump to be credible. Nor was it a supercharged engine, as that was speculated in the same report to possibly push the figure up to 55hp (and equally non-credible figure!) Atkins was keen to promote and did go on to build a supercharged Dougie so he might have been inflating the estimate to sell the idea.

-Doug
« Last Edit: 03 Jan 2019 at 04:17 by Doug »

Offline Hutch

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Re: DT/SW5 Engines
« Reply #15 on: 03 Jan 2019 at 21:43 »
Apologies for being off topic but here are links to the Stromboli and Buzzie Information on the 500 Owners Club website FYI,

https://www.500race.org/web/Marques/Stromboli.htm
https://www.500race.org/web/Marques/Buzzie.htm

-Ian


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #16 on: 04 Jan 2019 at 09:57 »
Hi Ian,

Thanks for those links.

Following a hint from Doug I'm working on a short article about 500cc racing and Douglas engines in it, which I hope some Forum members will find interesting.

Doug,

I have been digging around in  back copies of the 500 magazine - also called "Iota" - for info about Duggie engines. It really just confirms what you were saying about rev limits and power outputs. There are also some not so veiled hints about the truthfulness of some claims and a warning about buying Special Engines from spivs!!

I found an article written in 1947 by Gregor Grant, a reputable motorsports journalist. Grant reports that Rex Judd, who apparently was a  exponent on tuning DT engines in the late 20s, told him that a standard DT engine in good condition running on alcohol put out 27 bhp at 55000 rpm. He also says the the absolute maximum recorded was 37 at 6500 to 7000 rpm in 1930. That was a specially assembled works tuned engine tested in the factory. He says that 25 - 27 bhp was pretty good for a DT engine.

Gregor goes on to remind readers that in 1947 it was almost 20 years since these engines were built and tested, and the chances of a 500 builder having a genuine Judd/Dixon engine still in good condition and in original tune were extremely remote. He goes on to say that the only way for them to get the high outputs quoted for a DT5 engine would be to employ Freddie Dixon and Rex Judd to build them one from new parts!!

He implies that the engines that Buzzie and Stromboli had installed would be worn engines producing considerably less power than the 25 ish mentioned above. Certainly I have not seen any suggestion that Jim Bosisto ever did any engine work.

There are frequent mentions in race reports of the time that it was difficult to keep the DT engine running on both cylinders, on both speedway bikes and in 500 cars. Gregor Grant thought that this should be solved in the 1940s with the ready availability of improved spark plugs developed for aero engines during the war. Both Buzzie and the Howe car put their problems down to better cooling on the front cylinder than the rear, with the rear overheating and misfiring. I wonder if you have any suggestions as to the type of modern plugs to use in these engines.

One thing I noticed on my engines is how the plugs are in effect sitting in a small chamber above the combustion chamber rather than in the chamber itself, which is modern practice. The size of the hole between the plug chamber and the combustion chambers is quite different between the two engines. I attach some pics to illustrate this.

Thanks for the info about the head gaskets. Ill need to get to work on some rings, unless I can find one of the sprinters in the UK has commissioned some and would let me get involved. I don't think I'm skillful enough to make them myself and be sure they would fit exactly enough to guarantee a seal. What sort of torque do you use to crush the copper sufficiently?

My MG crank was made by Farndon. I only bought the one, but I expect that in those days they had a steady demand for them so had already invested in the tooling etc to make them individually. I suppose its possible they may be able to make one off cranks if they made the existing batch. I'm struck by the similarities of tuning my MG engine and the DT engine. I too had better valve retaining caps allied with thinner stem valves made to increase the safe rev limit and increase the airflow through the ports! But for now all of that sort of thing is not on the cards. I need to concentrate on getting an engine running at up to 5000 rpm using the parts I have.....

best wishes

Douglas

Offline eddie

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Re: DT/SW5 Engines
« Reply #17 on: 04 Jan 2019 at 12:07 »
Douglas,
                On our sprint bikes we are using long reach 14mm NGK B9EGV plugs. The heads have had the spark plug holes drilled right through, and then fitted with screwed adaptors which were then brazed in. (see attached photos). Any tuning increases the demand for a good spark - if you need to get a magneto rewound, entrust the work to Paul Lydford at APL Magnetos, Shaftesbury, Dorset, and get him to fit 2 capacitors (as he does for the sprint boys).
  With regard to the cylinder head gasket rings - as Doug said, they need to be rolled from copper bar, and then have the joint TIG welded. An alternative way of achieving the diamond shape is to start off with a circular section ring - then using a couple of otherwise scrap barrels - place the ring in the groove on the first barrel, then invert the second barrel and position it on top - then squeeze the whole lot in a hydraulic press (you may need to re-anneal the ring and give it a second squeeze). If you are lucky enough to find someone with rings to dispose of - be careful, they come in 2 diameters, depending on whether they were intended for 500 or 600cc motors. To further confuse matters, some 600 barrels were produced with the smaller rings!

  Regards,
                 Eddie.

Offline Doug

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Re: DT/SW5 Engines
« Reply #18 on: 04 Jan 2019 at 14:56 »
Douglas,

The only other horsepower figures I have seen are those cited in "The Best Twin". In there, Jeff Clew gives the standard 500DT  engine as 27hp but for an additional ten quid the factory could supply an engine assembled by Rex Judd and Freddie Dixon that produced 32hp. The "Red Devil" models, tuned by Bert Dixon, were cited as producing 34.5hp.

The small drilled hole between the spark plug and the combustion chamber is an anti-oiling feature. It was expected back in the day to have a lot of oil passing the rings so that was their means of keeping the plug dry. They seem to work fine, but you have to factor them in to the ignition timing. Most have been drilled out by now, and you need to retard the timing as the main charge lights faster with direct access to the spark. My road going '34 ohv still has them, and it seems happy with about 38 degrees advance.

Obviously due to the timing disparity, you cannot mix and match cylinder heads with and without the anti-fouling pocket!

-Doug

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #19 on: 04 Jan 2019 at 20:23 »
I posted an article here https://www.douglasmotorcycles.net/index.php?topic=7281.0 on Douglas engines and 500 cc racing in the racing section of the forum, which I hope might be of interest.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #20 on: 05 Jan 2019 at 17:11 »
Hi Eddie

Thanks for the info about the head gasket, the plugs and magneto. Of all the issues that have come up the head gasket is the one that is concerning me the most. I will have to look around for someone who can tig weld the rings following the procedure you and Doug describe. What sort of torque do you tighten the head down to?'

I hadn't thought of looking round for any rings because I didn't realised they were re usable. However I will advertise for some, more in hope than anticipation. Also I wondered if anyone had tried using a conventional modern head gasket, the copper/aluminium asbestos copper/aluminium sandwich type? I thought it might expand into the ring when tightened down to provide an additional seal to the flat surface to surface seal.

I have two magnetos, one is a rather sorry looking EIC affair which is incomplete and I dont think is the right one for the engine. However the other one is a Bosch MD2 x4 model, which fits the engine and looks to be in good condition and complete. So I'll follow your advice and send it to Paul Lydford  for an overhaul and ask them to fit the second capacitor. I don't want to be worrying about a decent spark whilst I've got so many unknowns to deal with elsewhere.

Best wishes
Douglas

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #21 on: 05 Jan 2019 at 17:29 »
Doug

Thanks for the info on the plug holes and the little chambers. I did wonder if they were to protect the plug in some way, but I hadn't thought about fouling issues. I'll probably leave them as they are in on one of the pairs of heads for the first engine, with a view to doing Eddies mod and using modern 14mm plugs on the tuned engine when I build it.

It looks like all the bits of info of power outputs are pointing towards the same answers! I'd not heard about the Red Devils engines, I suppose that they were for factory riders bikes?

best wishes

Douglas

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #22 on: 05 Jan 2019 at 19:22 »
I suppose the engine isn't going to get running by me typing on the internet!

So today I thought I should go out into the garage and start investigating the hardware in the light of what I've learnt. I need to measure the engine up to estimate the compression ratio. The first thing I discovered is that with the cylinder head nuts I've got are so big I cant see how to get a socket or even a spanner on them to tighten up them up. I ground down the outsides of the jaws on an old 14mm open ender which allowed me to get them just starting to nip, but I'm lost for a way to tighten them properly let alone torque them down. I need some Douglas threaded K nuts lol. There must be a solution but I cant see it!

Next up I tried test fitting the camshaft gear, and noticed that the camshaft in one engine had 6 splines on the shaft where the drive gear sits, but that the other engine has a drive gear with 8 splines. Also it appeared to me that the splines are cut to different widths to control the orientation of the drive gear on the spline. I haven't yet tried to time the cam, as it all has to come apart for final inspection before final assembly.

The first engine came with a plethora of rocker shafts, and 5 rockers. I have managed to pair rocker shafts, rockers and inner mounting bolts to get four sets with not too much play. However I don't have any of the washers that go on either side of the oil/grease reservoirs. I get the imprecision that these are fibre washers, is that correct? Also I have read that the shafts which run through the rocker mountings and hold the lubricant reservoirs should have little wicks running through them. I wonder what these are made of, and how thick they are?

best wishes

Douglas

pics attached :-
8 spine cam and wheel
6 spine cam and wheel installed
Rocker sub assemblies



Offline Buzzie

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Re: DT/SW5 Engines
« Reply #23 on: 05 Jan 2019 at 19:28 »
Sorry, pics wont load. Ill try again later

Offline Doug

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Re: DT/SW5 Engines
« Reply #24 on: 06 Jan 2019 at 21:09 »
Douglas,

I got the impression that Bert Dixon and the "Red Devils" were not factory, but a outside tuner that happened to specialized in the DT engine.

The cylinder head nuts are a a very slim hex; even so, you usually need a thin wall tube socket or offset ring spanner to tighten them. 5/16-25 thread, #z385; they are also used on the bottom two crankcase half bolts.  I have them in nickel plated alloy steel and eventually will have them available in heat treated stainless steel like much of the other DT hardware I do. You don't need a lot of torque, usually just what you can apply with a six inch long wrench handle. 

The 8-spline camshaft is the more common one. It is the same spline as used on the road going models servo band brake levers. Late in the game (c1932?) and for reasons unknown they switched to a 6-spline for some of the racing/dirt track and aeronautical engines. However the 1932-35 ohv road models continued with the 8-spline. I have not noticed a master spline key to control orientation before. Certainly not on the 8-spline.  I only have one example of the 6-spline, and I cannot say I have looked at it that closely.

Make sure that the inner sleeve of the rocker arms is a snug fit between the perches. It is that which the perch clamps down upon, and since cast iron is not very flexible you don't want to make it have to deflect too much! They should be a snug fit. The rockers should have some end float, but often they have cut into the perches and worn grooves and have too much. I have seen some nasty shim jobs with spring washers that just made the problem worse, but the ultimate solution is to weld up the grooves with silicon bronze and mill flush. Often the ends of the rocker arms need building up to restore the length. The bore of the rocker tends to wear on a diagonal because of the off center thrust of the pushrod and valve. If not worn too badly, they can be honed to 12mm and new sleeves made from pre-hard 12mm Thompson shafting (the original size is 15/32). Often the sleeve seize and spin on the rocker shaft bolt, wearing it instead of the sleeve. New rocker arm bolts are available.

The only special washer for the oil/grease reservoir is the one underneath. This is a conical shape and originally was copper sheet wrapped around an asbestos core. Not available. I figured on mine I would just make them out of some temperature resistant polymer or solid copper. At the top, under the cap nut is a steel washer and then a fiber washer. There is some misconception as to what to put in the reservoir because of the grease fitting. If you do use grease, make sure is is a LOW temperature melting grease. The idea is once the engine warms up, capillary action starts and lubrication is fed to the rocker arm sleeve. One or more wicks are stuffed down the hole in the center of the rocker arm bolt to the bottom. The tails exit the slot, and lie in the bottom of the reservoir. The lubricant travels up to the slot in the rocker arm bolt by capillary action and down into the drilling and thence the rocker arm sleeve by siphon action. The bottom of the hole and exit to the sleeve is lower than the floor of the reservoir. When the engine cools down this stops, preventing the lube from just siphoning through and leaking out; an automatic shut off valve. Obviously you don't want to use a light oil that would wick at room temperature. But if you are only going to run the engine for short periods, something that starts to wick sooner rather than later is preferred. So a heavy oil is probably best. Originally the wick was probably cotton cord or string, but now machinery oiling felt is probably the best choice. Pipe cleaners can be used, just make sure they are not the synthetic type as they do not wick oil worth a damn! If you are only going to do demo runs, probably just taking the grease fittings out and applying a few drops of oil to the center of the rocker arm bolt would probably be best.

-Doug
« Last Edit: 06 Jan 2019 at 21:51 by Doug »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #25 on: 06 Jan 2019 at 21:43 »
Today I went to a huge Classic Car open day held in Bicester today at a business park dedicated to Classic and Veteran Car businesses of all sorts. One of the businesses was Classic Oils who specialise in supplying oils to classic and veteran cars, and their technical expert was there. So I lost no time in discussing the lubrication of my Douglas engines!

Following our discussions on here about oils I asked him if he could supply monograde fully synthetic oil. He told me that none was available in the UK, but that he knew it was available in the US where it was used by sprinters and Drag Racers. He asked me why I wanted a monograde oil, because he couldn't think of any circumstances in which a monograde would be a better solution than a multigrade oil. I outlined our discussions and he told me his opinion was that any lubrication requirement would have an optimum viscosity which would be more precisely met by a multigrade oil. He felt it was inevitable that in operation the oil would be at at a range of temperatures in the engine, and the optimum viscosity would only be available at all of these temperatures if it were a multigrade.

He also told me that if the engine was running on Methanol, only a high quality synthetic oil would be a suitable multigrade solution. The methanol could adversely contaminate mineral oils, even if only went through the engine just once due to the total loss system. He said that the only other solution that could survive this environment would be a monograde vegetable or fully synthetic oil.

He suggested the following fully synthetic multigrades available in the UK. Penrite Racing 15w50 or Racing 20w60, or Millers CFS 15w60.

What he had to say seemed to me to make sense, wonder what you guys think?

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #26 on: 08 Jan 2019 at 20:30 »
Hi Doug

There was a fair bit to digest in your last post! I've looked at my bits and pieces and have used those points as a check list so to speak. The remarks below refer to the first engine. As I've mentioned before I'm starting with that engine and leaving the second one til later.

Starting with the valve gear etc. Amazingly it all looks in really decent condition. The rocker inner tubes are a clearance fit between the perches, and the perches are virtually wear free. The rocker shafts are in good condition and are a clearance fit inside the inner tubes, although there is some wear where the rockers have obviously been moving on their inners. I have found four rocker shafts which have the little copper cones and the wrap around asbestos pieces. I will attach a photo. The ball ends of the rockers are in reasonable condition, but the pads that bear on the valves are worn. They probably would dress flat with a stone, but I would worry about how deep the surface hardening goes.

I notice one of the rockers has some holes drilled in the arms. See photo below. I wondered if these might be to do with the exhaust valve lifter. This system is a complete mystery to me. I've looked carefully at the bikes in the National Motorcycle Museum, some dont appear to have it fitted, and what I could see on the others left me none the wiser.

I read the info about the lubrication system with great interest. A lot of tips there for me to follow when I get to that stage. Particularly about the types of lubricants to use and the wicking material. I think a heavy oil would probably be my route forward. The engine is unlikely to run for more than about 20 minutes at a time before I would get the chance to top up the rocker shaft reservoirs.

I just read your link in an earlier post to your 2004 crankshaft post. I am in a bit of a quandary. The bottom end of the engine including the cylinders and pistons were all assembled by the company I mentioned at the outset, so at the moment I am unable to inspect these. My instructions were to get the engine in decent working condition and get it running, replacing worn parts as they thought necessary. My dilemma is I chose the company because they have a good reputation and I felt I could entrust them to rebuild the whole engine. They quickly did the work they have and were confident in it. Unfortunately the job stalled (for getting on for 10 years!!) when they couldn't find some of the parts and were defeated by the head gaskets.

So my dilemma is whether to take it all to pieces to check it all for wear and reassemble it myself or to trust the quality of their work. I certainly trust their experience in reassembling etc over my lack of experience. I will have to separate the two crank case parts to fit the missing gasket, and oil up the parts that have dried up and I cant reach from the outside. I can see from the outside that the crank end float of the crankshaft isnt excessive. The crank taper doesnt show excessive wear and but does have some localised damage. I will attach a few photos. The cylinder bores have no visible wear and have been nicely honed and the standard pistons and run well in them, the rings scraping oil as they rise and fall in the cylinders

I have measured the combustion chamber etc volumes to calculate the compression ratios. I estimate the CR is 9.8 to 1 for the fitted dome top pistons and a 0.188" spacer fitted under the cylinders. The flat top pistons would provide a CR of 6.75 to 1 if fitted. Seems about right for Methanol and pure petrol respectively.

You mention that you have some Douglas nuts. Can you supply these? I have searched on the Forum and have found mention of your conrods, and rocker arms etc, but no mention of fixings etc. Is there a website or a list anywhere? I will probably need a lot of new or reworked components for the second engine, but I definitely need a supply of nuts and studs to put the first engine together. I had a quick look at the valve gear on the second engine, and it will need a lot of attention.....

Best wishes
Douglas


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #27 on: 08 Jan 2019 at 20:34 »
Some photos

Offline Dave

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Re: DT/SW5 Engines
« Reply #28 on: 09 Jan 2019 at 21:16 »
Test post only.

We've been having problems displaying this topic.
Hopefully they are fixed now.

Dave

Offline Doug

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Re: DT/SW5 Engines
« Reply #29 on: 10 Jan 2019 at 07:32 »
Douglas,

Quote
There was a fair bit to digest in your last post!

No problem, get ready for some more indigestion!

Quote
The rocker inner tubes are a clearance fit between the perches…

Ideally there should not be any clearance, it should be a snug fit. Maybe a thou or two clearance but even a sheet of newsprint as a feeler gauge would probably indicate too much. Fortunately unless the rockers seize and the sleeve has been rotating, there is no reason for the sleeve ends to wear into the perch. That there are no grooves cut into the perch (from sleeve or rocker arm) is a good sign; usually if they are it is the bottom that suffers the most. In this picture you can see the groove the rocker arm cut in the perch but towards the center where the sleeve is clamped it is the virgin surface.



Even this is repairable by filling in with silicon bronze. The tricky bit is it is best milled flush (rather than filed) to make sure it is precise, square, and parallel to the opposing perch. Notice the owner’s file hash-marks to indicate valve position #3!



When they get this bad, one usually has to restore the length of the rocker arms too. (This set has non-standard pushrod tips, which were a feature of its competition history.)





Of course this undoes any heat treatment the rocker arm had, but sometimes a repaired rocker arm is better than no rocker arm. The tips for the valve stem and pushrod were case hardened, but I do not know exactly how deep. The bores do not seem to have been hardened at all. I don’t think the ends faces were either as the ones I have tested seem soft. Admittedly those are ones that have been badly worn, and the good ones I am not about to attack with a file to see if they are hard! In this case, the valve pad and the pushrod socket were restored with Stelite, so annealing the original case hardening was a moot point. Ideally the rocker arms should have been re-heat treated to restore the core properties (assuming they are a 4-5% nickel alloy steel like the crankshaft and connecting rods are made of) but these have been welded about and reconstructed so much (entirely new pushrod tips) that the client decided it wasn’t worth the bother. If they break (assuming the engine is ever started), then will just have to explore having all new rockers made.

In conjunction with that I re-profiled the valve pads, first to undercut for welding and then to machine the Stelite. For that it is handy to have a fixture to hold the rocker arms like this:




These rockers were in really bad shape, so I didn’t really check how thick the case was. It was mostly gone, they were worn that bad! And the pushrod pockets looked like they have been re-machined with a blunt drill. Since I was roughing away with carbide tooling, any residual hardness was not noticeable though I got the impression it was only a skin about 0.020 inch thick at most at the valve pad. I probably do have some other junk rockers that I can grind back and check on the hardness tester if I get a spare moment. Where I did such on original connecting rod big end race I had to send the work out for micro hardness testing. Conventional testing with a diamond penetrator uses high loads (150kg for HRc) which give a false reading (too deep an impression) when done close to the edge of the sample. The conrods were only case hardened 0.030 inch deep. My circa 1940s Wilson hardness tester will do lighter loads (less than 150kg) for Rockwell, Vickers, and Brinell scales for when testing on thin samples (sheet metal), but lacks the sensitivity for micro harness testing or testing to within 0.005 inch of an edge. So it is not ideal for testing case depth.

The holes in the sides of the rocker arm were added by some tyro boy-racer to lighten the valve gear. It has nothing to do with the valve lifting mechanism. The latter is attached to the ‘access plate under the magneto. See here:



Some rocker arms did have lugs for auxiliary extension springs between the two rocker arms, but the DT motors don’t seem to have used that. They used duplex valve springs on the inlet, triple on the exhaust, and the auxiliary springs were at the base of the pushrods. The pushrod springs were the same part number as the 350EW inner valve springs!  Your rockers have all been ‘worked over’ to some extent or the other. Originally they would have been left in the as forged or stamped (to use the UK term) condition. So you would see the part numbers 8550 and 8551 and the arms would continue right around the body as a shallow rib. But as I said, most have been sanded smooth and polished by now and it is getting hard to find an original, unmolested set of rocker arms. Here is a pair that have never been machined:



Yep, as you figured out it takes a while for the heat to get to the rocker arm reservoirs and for the lubrication to start to flow. If you only run the engine less than ten minutes, the lube might not start flowing until after the engine stops! Later engines with the enclosed valve gear just had a grease fitting into the center hollow of the rocker arm spindle. Though a grease fitting, these too probably were fed with heavy oil. Unfortunately I don’t know of any owner’s manual for these models existing that would give a clue as to how often Douglas suggested lubricating the spindles. Surely they could not have expected the owner to lube the spindles prior to starting the engine every time? Today, one would not be using the engine every day but on special events, so going around and doing all the lube points is not such a big deal. Better over lubed than under lubed.

As for the crankshaft, impossible for me to venture an assessment. I don’t know the name of the firm, and even if I did I unlikely ever had any business with them (unless Alpha Bearings) to have formed an opinion based on experience. I cannot imagine there are any commercial firms that have experience on Douglas prewar ohv crankshafts (or any prewar Douglas crankshafts!) As you probably gathered, I do my own and don’t trust anyone else! I think most folk that are still racing these old Dougie engines have learned how to rebuild their own crankshafts.

Some indicators for a competent job would be did they provide an assessment or documentation of the components? Ideally photos of the crankpin or conrod surfaces showing any issues, or hopefully pristine surfaces? Did they measure and document how round the crankpins were? They do wear oval. Did they indicate the crank to see if it was bent? Was it crack checked? Lack of documentation would worry me. Also previously mentioned is checking the big end cages for square. A bent crank and/or bent cages can cause damage to the center web like this:



This crank came out of one of the late Bill Dent's sprinter engines, so apparently he didn't check his cages either!

Murphy ’s Law mandates it will always damage the component that is the most expensive and/or difficult to repair. Never the more easily repairable or replaceable counterweight, oh certainly not! Even this damage is repairable, though it is a risky job.

Once it is assembled, all this is hidden. You can try for perceived feel for radial clearance, but that is hard to do and the ability of the rod to rock from side to side can obscure any pure radial clearance. One thing you can check after the fact is the side clearance of the rod. If the sides of the rod are not worn and the counterweights are the original and returned to their original places the setting should not – in theory – have changed. The counterweights are marked T and F for which side they belong, and a match number that should correspond to that on the crank center web. If you go around the side of the conrod bigend with a feeler gauge and get a variable side clearance or too much that is an indicator they were not paying attention to the details.

As you would have saw in the post on crank assembly, the counterweights key into a groove on the haunch of the throw and the other end is locked by a tapered cotter. That means the lateral position of each counterweight and throw will vary a little and the side clearance of the conrod with it. Hence marking the counterweights so they are always returned to the original fitted position. Now decades later when you mix and match parts or of the crank has been bent and straightened, all that goes out the window. So the best practice is to skim the face of the center web square (it is a case hardened surface) and face the counterweight in-situ to the correct distance. That does require a fixture to offset the throws in the lathe, and a tool holder to reach in where the conrod would be.



It is fairly easy to build up the counterweight lip with something like Stelite (the original counterweights were, oddly, not hardened in any way) so that you have extra material to machine to size.



I have come across cases where the counterweight was machined to final thickness in the mill. Unfortunately the back face of the counterweight (lying on the machine table) is not always square to the crankshaft, it is how it registers in the groove and the tapered cotter that determines how square it sits. Hence it is better to finish machine the counterweight thrust surface on the crankshaft in the lathe.

I do not like the original cotters. They are too soft in my opinion and ones I have removed show serious galling from the much harder crankshaft. They have to be soft so the tail can be swelled by riveting over. I have several issues with this. If the cotter galls it might seem tight because it is binding before it has really wedged the counterweight tight. If the counterweight is not tight, it will work loose. Not maybe, just a matter of when. The cotters should never be reused, but people do. The high spots from galling get dressed down with a file but that leaves the low spots. On re-installation the cotter goes in until it hits the ramp at the end of the depression and gives a false impression of how tight it is. Nor is the pressure spread evenly over the whole facet of the cotter. Lastly, in riveting the end over, one has to be careful you are not driving the cotter back out of the hole. Nor will it ever be a good rivet job as the tail of the cotter is not even a full cylinder, so it is never going to fill up the hole. Removing the cotters usually entails grinding the tail off (which hopefully precludes using it over!) and driving it out. The ends still in the hole usually are slightly swelled, so that has to be driven back through the hole. Nor are the holes through the counterweight square. They are usually curved because the reamer (or drill) deflected into the opening for the throw. This is not entirely such a bad thing, as the cotter only need bear against the hole directly opposite the point of pressure created by the v-notch in the throw. I do take a round pillar file and straighten the center half inch of the hole so that it does have a good bearing for the cotter. The rest of the hole does not actually matter that much.

I make new cotters from air hardening tool steel. Same alloy and hardened and tempered same as I would use for a cold chisel. I straighten the center of the counterweight hole as described above and take an oil stone and polish the face of the cotter and the vee-grove in the crankshaft if they are in anyway rough. Obviously the tails cannot be riveted over, so I paint of film of Loctite on the backside of the cotter (the cylindrical side) and they stay put. I drive the cotters in until the assembly rings, indicating the cotters are truly tight and seated solid. You tend to just get a dull sound with the original, soft cotters. Making cotters requires a fixture, of course!




The first facet is easy as you just need an inclined plane. It is when you get to the second facet you realize you have to clamp on something that is no longer parallel! Hence the removable stuffer/jaw/packing plate with a mating taper. You end up making three cotters. The first is a trial cotter that you drive in and see how much (or little) tail is sticking out of the counterweight. Then you adjust the depth of cut for the other two. It is not practical to go back and cut more off once the facets are machined (work holding issues); easier just to mill another pin. Hence making a test cotter for sizing purposes. I suppose you could sand the faces to take a little more off, but if you do not sand exactly the same amount off of both faces the centering of the cotter will change and shift/tilt the counterweight slightly, altering the side clearance on the conrod. Also if the facets are not square, they will not be a good seat against the vee-notch.  So I machine them, where I know exactly how much is being removed and fixture ensures the angle and squareness. Both cotters never end up machined identical, so I mark the cotters T and F, like the counterweights are.

One should not rely on the cotter entirely to hold the counterweight. The counterweights should be a snug fit on the throws prior to installing the cotters. Tapping them on and into place with a mallet is ideal. Again, with mix and match parts sometimes the counterweight slips on too easily or even rattles when in place. If it is loose, it will eventually loosen the cotter, no matter what type it is. It is perfectly acceptable to pinch the counterweights slightly in a vice so they are tight on the throws. Better yet is to pinch the opening ever so slightly smaller and them skim the opening in the milling machine for a nice precision fit on the flat sides of the throws. The surface does not have to clean up 100%, just enough to give a good bearing surface to stop the throw from shuffling about. Again, if you can install the counterweights by hand without resorting to a few modest taps from a rawhide mallet, they are probably too loose.

While the Douglas crank assembly is not rocket science, it is not like rebuilding the bottom end of your BSA. Also to do a good job does require making a few fixtures/tooling.

Oh, and I was just reminded by looking at a picture there actually are four segments to the crankcase joint gasket.





-Doug

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #30 on: 10 Jan 2019 at 17:24 »
When we had the Forum issue a few days back I was unable to post some pics I mentioned, so here they are now.They are of my first engine:


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #31 on: 10 Jan 2019 at 17:32 »
And  some of the pistons and my impression to measure the volume of the valve dome

Im sorry, but I cant upload any more pics, and I dont want to try again for fear of locking the thread again
« Last Edit: 10 Jan 2019 at 17:39 by Buzzie »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #32 on: 10 Jan 2019 at 20:23 »
Hi Doug

You were right to warn me of indigestion! I have read through your post, and decided to break it up a bit and think about my valve gear first, and move onto the bottom end later!

I have re examined my valve gear more carefully in the light of your remarks. They either must have had limited careful use or have been refurbished properly using similar techniques you described The rocker tubes are very close to being an interference fit. I certainly cant get a feeler gauge between the perches and the end of the tubes. The perches themselves are pretty much unmarked.

The rockers are a different issue. They are a motley collection. Two have been polished, one of which has been chromed, and two are unmolested. The cups are in good condition, but as I already mentioned the pads are all worn. They are a bit worn internally, but they don't generate a lot of play. I do have an extra rocker, but it is significantly worn around the axial hole and is polished and chromed.

All the valves on the first engine set up by the engine builders have double valve springs. The other engine only has single valve springs fitted. Its also likely that the springs are all pretty tired by now. The push rods seem to be fitted with double springs fitted, but they don't look very strong. Both engines have the same types of springs fitted.



I did find a cover that goes underneath the magneto which has the lifter rockers fitted, but no sign of the rest of the mechanism you pictured in any of the engine parts. As I will be starting the engine with a donkey engine turning the back wheels(jacked up off the ground) I was wondering if I would need the lifter mechaniasm?

At this point I should mention that it is most unlikely there is any cross pollination between the two engines. I bought the first one as a pile of bits in about 2000 from an LDMCC silent auction. There were many more parts than needed to build one engine, some parts that probably don't come from a DT engine and a few parts completely missing. The second engine was bought on Ebay in November. It had been fairly recently partially disassembled and was sold as complete. It is – almost!!

I did find a cover that goes underneath the magneto which has the lifter rockers fitted, but no sign of the rest of the mechanism you pictured in any of the engine parts. As I will be starting the engine with a donkey engine turning the back wheels(jacked up off the ground) I was wondering if I would need the lifter mechaniasm?

Another little oddity I found was that two of the grease reservoirs have a little spigot split axially cast into them. I have about 10 ordinary ones in total, and these two odd men out. They seem identical in every other way to the others

The rocker gear etc in the other engine seems much more worn, although I haven't dismantled it from the head. So my plan is to bash on with engine 1 s valve gear in its current condition, with a view in due course to having a full refurbishment of the second set done for the second engine.

As posting pictures is still causing me problems I'm going to try and upload this section, and then post a second piece about the bottom end.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #33 on: 10 Jan 2019 at 21:59 »
Doug

I have reflected on your notes about the bottom end of the first engine.

I don't have any notes or pictures from the engine builders. Having said in my experience that wouldn't be normal practice over here. We tend to chose engine builders carefully based on reputation and first hand experience of ourselves and our close circle, and then take them on their word for their work.

I fully accept your warnings about what should be done, and what could or could not have been done. I too think that they wont have built a DT engine before. But they must have some experience to have the confidence in their ability to do the work. They are a serious engineering company and there was none of that characteristic sucking though the teeth you normally get in the UK when they are worried about a task! I guess I just have to try and pick a way of minimising the risk by balancing the risk of their work being bad, against the risk of undoing good work which I cant get rectified.

So my plan is to split the crankcase and inspect the assembled crank as far as I can with a view to assessing the state of it and the quality of work done using your comments and common sense, before deciding what to do next. That decision will probably be the most difficult part of this phase of work.

I have in total three crank shafts, and five counter weights. At the moment I have no way of knowing the state of the crank and two counter weights in engine 1. The second crank came with engine 2 and has two loose counter weights and no cotters. The third crank I bought on ebay from someone else. It has one conrod with bearings and a counter weights with cotter fitted. I also have another loose conrod with no bearings.

The second crank isn't too bright. It was rusted on the surface in places, including on the bearing surfaces, I have polished this out and there doesn't appear to be any significant elliptical wear, although both big end journals have about a thou of taper on them. They also have some very light pitting where they were rusty. The counter weights are both marked F, and their batch numbers don't match the crank or each other.

The third crank is very rusty, and the counter weight is also stamped F, and its batch numbers doesn't match the crank or anything else I have! So I get the feeling that sorting out engine 1 will be a breeze compared with achieving my aim of getting good quality components in engine 2! I know in my gut I need a new crank and new conrods for that engine, and finding the crank at least will be a big task.

On a more positive note I have laid out all the components I have earmarked for engine 1. There are a few things missing, but not many. My next job is to list the missing items. I have also laid out the bits that I have which I cant identify. They may not be DT parts or indeed even Douglas parts. But if you or anyone else can identify any of them it would be a great help. Finally I have put aside the parts for engine 2 for now, although they are laid out incase I need to raid them!

The bottom end is a bit more of a worry to me, because the sort of work you describe is not something I am able to tackle. My experience and equipment are essentially drawn from tuning and building up post war car engines. New parts have generally been available for these and the UK still has a pool of expertise in machining such parts when needed. So I understand the need to do things properly, but not how to carry out some of the specialised jobs you mention!

I feel relatively confident that if I had a complete set of new component parts available I could, using your notes and my experience build up a DT crankshaft and conrod assembly. I'm far from being able to get those components though!!

On a happier note a chance discussion at the gym yesterday identified a local man who has "several Douglas'". My informant is in the same local branch of the VMCC as him, and is going to try and get me an introduction......

Offline carl denton

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Re: DT/SW5 Engines
« Reply #34 on: 11 Jan 2019 at 12:42 »
got to say this is one of the best project if have read on the forum for a long time look forwarded to see how it turns out , it will be of a big help to me as I have got a complete bike to put back together . it was taken apart by a person I did not know over 30 years ago .


yours carl.

Offline Doug

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Re: DT/SW5 Engines
« Reply #35 on: 11 Jan 2019 at 17:52 »
Douglas,

The pushrods should only have single springs, one each pushrod. There are two types. The earlier version has a barrel shaped spring and the later a conical spring.



As mentioned these are the same part number as the 350EW valve spring and presumably reflected a change in the supplies for the EW over time. I don’t know exactly when the style changed over but in my mind I arbitrarily place them as ‘tall airbox’ and ‘short airbox’ era. All I know is the one predates the other because the barrel style has the assembly nickel plated and the conical style had the hardware chromed. The later could have been re-plated, but I know the provenance from the early-mid fifties onward and know it has been untouched since then. The LDMCC prewar spares has the 350EW valve springs, but when used as the auxiliary pushrod springs on the DT they rarely need replacing.

On my 1934 OW1, which was a later iteration of the DT engine, I have the exhaust vale lift mechanism but never attached a cable to it. That has about 6.25:1 or 6:5:1 compression and it is not a problem to kickstart; even given the ridiculously high and awkward position of the kickstart lever because the gearbox is up under the saddle.

I have not seen rocker spindle grease reservoirs with that cast tit on them; a new one on me. Some of the TT bikes, and later by individuals copying the TT bikes, had auxiliary oiling to the valve guides. This was by drilling hollow the stud that holds the tappet retaining plate (seen above), and through into the crankcase. Then a banjo and some oil fitting and small copper tubes carried oil mist to the tops side of the cylinder heads and the tubes were pressed into hole drilled through the head and guide. Maybe this was some alternate idea as a source of lubrication supply.  Having said that, the machining of the off-center hole, slot, and cross hole (for a cotter pin?) is really unusual and has be baffled as to purpose.

One other thing you can ‘test’ if you have the crankshaft out is to twirl the conrod around the crankpins. It is natural that they will hunt from side but there should be no tendency for them to thread sideways and bear firmly against the center web or the counterweight. Such helical inclination is a certain indicator of a wracked big end cage.   

Light pitting from rust on the crankpin is acceptable. It is certainly not ideal, but beggars cannot be choosers. Worse is if the surfaces of the crankpin or rod have started to spall or brinell. You can take an oilstone an relive ever so slightly around ‘pothole’ to take the pressure off the edges (assuming the roller will span the defect) but it is always at high risk of more chunks breaking loose and circulating through the rollers and the rest of the engine. If it has started to brinell, there are already ruptures throughout the crankpin between the hard surface skin and the softer underlying core. The heat treatment process Douglas used was rather brutal (water quench on such a large part!) and a side effect was a very abrupt transition between case and core. Don’t lose any sleep over it, they all probably are riddled with cracks! A more gradual transition would have made a stronger interface.

Taper on the crankpins is unusual and was probably a manufacturing fault that has been there since day one. Wear is inevitably elliptical, with of course the worst being in plane with the crank throws due to the inertial and loading of the piston/conrods. As mentioned in the crankshaft post, about all you can do is lap the pins lightly. Grinding them undersize (if you could find anyone to do it) inhibits reassembly.

Given the expected miss-match of counterweights, they all need to be ‘fettled’ to whatever crankshaft the eventually end up residing on. Just as the factory would have done when they originally built them.         

Parts identification.
A)  Bastardized pushrod spring retainer plate.
B)  Part of the clutch release mechanism of the Douglas Flywheel clutch.
C)  Douglas flywheel clutch spring plate.
D)  Some of the Douglas side valve models used cast iron valve guides of this shape, but so did a lot of other things. Not DT unless the flange diameter has been reduced.
E) Looks like it might be the magneto gear from a 350EW. If the face recess has an internal thread just inboard of the teeth, than almost certainly so and for the model with the cone clutch to drive a dyno.
F) Some of the Douglas lightweight side valves had the oil pump worm integral with the engine pinion, like this.
G) Looks like the port flange removed from a DT exhaust system.



By the way, the cast aluminum engine clamps on the table seen in your previous post are the type used on Douglas side valve engines. The originals are a pair of steel bars that spanned the width of the frame. These were plated, though on later road going bikes they were painted black. Despite being steel they are usually bent! The original bolts (three shown) used Thackray type shake proof washers and were drilled for safety wire.




-Doug
« Last Edit: 28 Jan 2019 at 00:41 by Doug »

Offline graeme

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Re: DT/SW5 Engines
« Reply #36 on: 12 Jan 2019 at 06:48 »
Fascinating thread for sure.
Douglas, in thinking about your dilemma in building up the second engine with all the difficulties in refurbishing a crank where the bob weights have come loose, an alternative is to use a modified BMW R60 crank - I know this because this was done in one of the DT engines I own. The work wasn't done by me I might add, but a chap in Australia made several of these cranks in the 1980s
Cheers, Graeme

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #37 on: 13 Jan 2019 at 12:42 »
Hi Carl

Glad you are enjoying the thread. Doug and Eddie have posted some great stuff and I'm beginning to feel that I might actually get engine no 1 running!!!

Would be fantastic to hear and see some pics something about your project, and the parts you have, what you need to find and what work needs to be carried out  :)

Best wishes

Douglas

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #38 on: 13 Jan 2019 at 13:14 »
Hi Graeme

Im glad you are finding the thread interesting. Im planning to keep it going so that people can follow the story and learn form it as they build and operate their DT engines.

That's really interesting about your engine, and its BMW crank.  Using that crank could be a way to go, because I am concerned about the reliability of engine no 2 with one of the cranks I have fitted. The two I have left are both a bit grotty, and as Doug has explained my options for refurbishing them to a good standard are somewhat limited.

 I wonder if you have any information about the conversion? What modifications were needed to the crank and to the crankcase? I wonder if he used the BMW conrods or retained the Douglas ones?

I have had a quick look on the internet about these cranks. The good news is that one wouldn't be too hard to find. However I notice the stroke is less than the DT engine stroke (73mm vs 82mm). I reckon this would mean a capacity of just over 440cc for the engine. It did occur to me that the builder might of used 600 or even 750 cc cylinder barrels to bring up the capacity.

Best wishes
Douglas

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #39 on: 13 Jan 2019 at 16:14 »
Doug

Thanks for your latest post. Some more of my worries addressed!

Those crankshaft assembly tests you mention will be very useful. I will certainly check those things,  along with the suggestions you have already mentioned, when I “crack” the crankcase on the first engine. I'm just plucking up the courage. :-)

I have now re visited my parts list check list, and am very pleased to see how many items I have now positively identified with your help. I have still a few things unexplained though.

Cylinder Group

There are two part numbers (4994 and 10012) for the same description - “inner valve springs inlet and exhaust” My cylinder heads both have double valve springs on all four valves.

#7168 is a “superlock washer” on the rocker spindles front and rear. Would this be a spring washer or something more sophisticated?

I'm assuming that #8792  “oil trough front and rear” are the rocker grease reservoirs that feed the wicks in the rockers.

Crankshaft

#912 and #766 ball and spring respectively for Non Return Valve. I don't recall seeing that mentioned anywhere in our discussion or elsewhere, or anything like them in any of my crankshafts

Crankcase Breather Group

This group is a complete mystery to me. Obviously pressure would build up in the crankcase, but I can't think where a breather would mount on the crankcase nor have I seen any parts in my collection that could be part of a breather assembly.

Exhaust Lift Mechanism Group

I've decided to do without this Group!

Thanks also for identifying some of the parts in my Mystery Collection. I won't be needing a working Douglas clutch as Buzzie used the clutch in the Norton Gearbox assembly. I just need to find a way of locking the flywheel to the drive sprocket. I will however find the exhaust flange very useful, as I have an exhaust system to fabricate.

 I was wondering about the engine mounting claws. Engine 1 came without any means of clamping it to the frame. I had read something somewhere about engine mounting claws, and when I saw some on ebay I bought them. Engine 2 came with some steel mounting bars, similar to the ones you pictured, which I should be able to use on whichever engine is installed in Buzzie.

Hopefully someone with one of the side valve engines will be able to make use of those foreigners in my collection!

Best wishes
Douglas

Offline Doug

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Re: DT/SW5 Engines
« Reply #40 on: 13 Jan 2019 at 23:52 »
Douglas,

As mentioned, on the exhaust valves of the DT they originally used three springs. #4994 is the 350EW spring that I previously mentioned and it was used as the innermost spring. So technically #10012 should have been labeled the 'intermediate' or middle spring. But it is the inner spring on the inlet valve.

I don't think the valve timing on the exhausts was anymore radical than the inlet, so the purpose of the third spring on the exhaust was (besides wearing out the exhaust lobe quicker!) likely due to the realization that the heat was going to make the exhaust springs degrade in spring rate more quickly. LDMCC members can buy new DT valve springs via the Club. They should also have the EW springs, if you want to go triplex on the exhaust. The road bikes seemed to get by with just the duplex set.

Douglas had another way to combat heat transfer to the valve spring. Underneath the very large flange of the valve guide is a thin insulating mica washer. How effective it actually was, I am not so sure. With the enclosed valve gear models (1932-35) there was a air break between the roof of the port and the floor of the valve spring pocket that probably was more effective. Unfortunately the design also introduced a few new flaws! 

"Superlock Washer" was the term then for what we call a Thackray washer, or double coil washer. Two of the engine mounting bolts I posted a picture of earlier have their super lock washer. The other has a modern single coil lock washer. These are getting hard to find now, as only a few smaller sizes used on fifties and sixties British sports car carburetors seem to be still in production. In the larger sizes you have to keep an eye out for second hand hardware.

Engine breather. This is a small fitting of aluminum and brass that screws into the drive side wall. It vents oil mist onto the primary chain. If the chain breaks, it usually is broken off. The following picture is of a 1934-35 crankcase, but it used the exact same breather. There is a light spring and a sheet metal disk inside that serve as the one-way valve.




-Doug
« Last Edit: 28 Jan 2019 at 00:42 by Doug »

Offline Doug

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Re: DT/SW5 Engines
« Reply #41 on: 14 Jan 2019 at 00:09 »
Douglas,

The original DT solid flywheel had the sprocket threaded to the flywheel with a left-hand thread, and then locked with a right-hand thread ring nut. I sent you a drawing of that in 2010 I think.

There was a late version with a bolt on flywheel to a separate hub, but I think that too used the same screw on sprocket.

-Doug


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #42 on: 15 Jan 2019 at 17:08 »
Hi Doug,

Yet more useful and interesting information there Doug. Thank you again.

I now understand the full story with the valve springs. That all drops into place. As I'm setting a 5000 rpm rev limit on engine #1 I think I'll stick with the springs I have initially. I will however see what the situation is with the LDMCC springs in case I need them.

I have used Thackery Washers on my previous cars, but haven't tried to buy any lately. Both engines have washers fitted under those bolts. One used standard spring washers, but the other (engine 1) had some completely squashed Thackery Washers crammed onto the bolts by decades of grime and habit! Ive taken one off and opened it out for fun. Dont think it would be very super now though.

I have found at least one part of the crankcase breather. It is the part that screws into the block. It has a disc fitted inside, but no sign of any spring, so it doesn't have a one way operation feature. The bit I have has a male tapped outlet, which may have had the stub outlet screwed onto it?

I'll need to have a closer look at those flywheels, the sprockets aren't showing any inclination to unscreww so some WD 40 and a heavier approach is needed! I don't recall seeing any flywheel drawings, I don't think I was active on this project in 2010. Were they sent by email?

Best wishes

Douglas

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #43 on: 15 Jan 2019 at 17:10 »
More pics

Offline Doug

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Re: DT/SW5 Engines
« Reply #44 on: 15 Jan 2019 at 17:41 »
Douglas,

I do have measurements for the crankcase breather, including the bits you are missing. However I would have to throw them on a drawing format and add some dimensions; they are not 'ready to go' as is.

Actually it looks more like 2004 and not 2010 that I provided some drawings for Buzzie. The original post was by "Halihat" whose first name was Douglas so I thought the same person again? It can be found here:

https://www.douglasmotorcycles.net/index.php?topic=261.msg686#msg686

The drawings were sent by email on November 10, 2004. That was via a previous email address I was using up to 2014, so to look for the messages is a little more involved than the present address. I found the reply, but not the sent message that has the attachments. But as I recall it was the flywheel, flywheel nut, Hepworth piston drawing, camshaft nut, and cam retaining plate and bolt(s). I still have the drawings of course, the email would just tell me what I had sent. PM me an email address.

-Doug

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #45 on: 17 Jan 2019 at 10:07 »
Doug

That info on the crankcase breather would be useful. I'm obviously going to have to make the bits that are missing. Its not urgent though as its a part that can be screwed on towards the end of the build, or even after its been test run on the bench? Knowing the info is available is all I need for now!

Your memory is much sharper then mine Doug. I'd completely forgotten about joining the forum before,and the discussions on here. 2004 was probably a couple of years after I bought the first engine. I was so daunted by the task and short of time back then that I gave the job to the company we've discussed before. I only just got it back!!  I also didn't remember about the Buzzie website that Id built. Its long gone now, no doubt I stopped paying the url registration fees!

I had a computer meltdown a few years ago and lost all my old emails, and my stored documents etc. Luckily I had a good deal of it backed up on an old laptop, and a good nose round it has found quite a few documents from you. I've got the crank shaft drawing and your articles on crankshafts and on main bearings and crankcase ( I think I gave the company I used a copy, hopefully they read it at some point!). I've also got your articles on Douglas Cylinder Heads and the Magneto Bearing extractor. However I cant find any signs of info on flywheel, flywheel nut, Hepworth piston drawing, camshaft nut, and cam retaining plate and bolt(s). Either they have gone down my earth spike or I didnt get them. Either way they would be very useful, so I'll PM you my current email address.

I've been reflecting on the Thackery washers. (I have found some from a supplier in Scotland, and had a Cinderella moment this morning when I fitted one on a cradle mounting bolt). When I've used them before it was to mount Weber carburetors onto the manifold. They were to provide some anti vibration resilience to protect the carbs. They were stood off from the manifold on rubber O rings and held in place by Thackery washers under the mounting bolts. These were carefully tightened to achieve a specific spacing between coils to provide sufficient clamping force whilst allowing the carbs to move under the controlled play provided by the washers. The old washers on the bolts I have were obviously tightened to close the coils right up, so I assume they arent used to provide a resilient mounting. Which leaves me wondering why Thackery rather than single coil spring washers were fitted?

Best wishes
Douglas

Offline Doug

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Re: DT/SW5 Engines
« Reply #46 on: 20 Jan 2019 at 00:58 »
Douglas,

I think the theory and effectiveness of lock washers has been debated ever since they were invented. The common argument against is most designs (but not all) do not come into action until the joint has already started to loosen. They compensate for loosening, not prevent loosening. Be that as it may, they seem to work. The alternative would be a tab washer or a Spiralock (TM) type of thread.

I am not sure why they chose a "Superlock Washer" (Thackray) over a conventional split lock washer. In the case of the DT engine mounting bolts, they are drilled for safety wire. Maybe it was the fad of the day. Certainly Thackray washers lived on because they did provide a greater range over which they maintained friction. A role that would eventually be taken over by the more economically produced wave washer. Besides postwar British sports car carburetors, they can also be found in the handlebar control levers for carburetor and magneto to load the friction insert.

I did save the pages from the Buzzie website, if you want to reconstruct it!

-Doug
« Last Edit: 28 Jan 2019 at 00:39 by Doug »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #47 on: 20 Jan 2019 at 09:53 »
Doug,

One of the sets of engine mounting cradle bolts I have is drilled for lock wire. It was very popular in car racing circles twenty years ago, but of course while effective it isnt so practical on cars which are constantly being taken to bits. With the advent of nyloc nuts, K nuts and thread locking compounds wire locking seems to be out of fashion. I do however still have a good stock of wire and one of those special pliers that neatly twist the wire …..... But then lock wire definitely only works when the nut starts to loosen

I have to confess that I seem to have got my knickers in a bit of a twist over the application of superwashers on the DT engine. For some reason I got it into my head they were used on the engine cradle bolts because I found them on one of the sets of engine mounting bolts I have, but they are not mentioned on the parts list. They are of course shown as being part of the rocker arm pivot assemblies, but I'm not sure where they would have been fitted.

I have an ongoing problem with the inboard drive shaft bolts on my modern racer coming loose. I've tried every solution and combination of solutions possible except lock wiring because of practical difficulties. One of my friends who spent his life as a development engineer working for many big automotive corporations, including Fordwho he tells me did an extensive study on the effectiveness of locking devices. Their conclusion was that the most critical factor was the the surfaces at each end of the fastener had to be flat and parallel. The design of the CV boot on my car precludes this, so for the moment we just re-tighten the nuts after each run, and don't enter long races!

My, you are a very efficient squirrel! I lost my local copy of the Buzzie website in my meltdown, so yes it would be nice to have the pages back. I could resurrect the site, or also I am considering a Facebook page for Buzzie.

Douglas

Offline Doug

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Re: DT/SW5 Engines
« Reply #48 on: 20 Jan 2019 at 15:45 »
Douglas,

Good point, the spares list only calls the engine anchorage bolt washer (#744) a "washer". It does not get the special designation "Superlock" as does the one for the rocker spindles. I have seen the Thackray washers on several different DT engines and assumed that they were standard fitment, but I may have jumped to conclusions. A Superlock washer might not even be the same as a Thackray washer. As for rocker spindles, I have seen quite a mixture of hardware on rocker spindles (when present!), but the common split helical lock washer, thicker than the modern equivalent, seems the most common. I just assumed (again) that they had all been replaced by what was readily available.

Thackray washers were around at the time. They were being advertised as early as 1878 by Messrs. Hydes & Bennett, of Sheffield; stated as sole manufacturer. It was also stated that the design had been patented two years prior but a search of the 1870-1880 time period has not turned up the record. The problem is compounded by seeming innumerable variations on spelling!



It does not list "for Douglas engines", so...



As for Superlock washer, they are more elusive. I did find a mention in a 1922 engineering periodical. So it too would have been available, but it is not what I thought it would be nor have I ever seen one on a Douglas.



Actually I initially came across a modern incarnation of this that looked more like an external snap ring, used currently in the maritime field. I dismissed the use of Superlock in that case just to be a euphemism, like 'stupendous washer', 'ultralock', or some other marketing department derived euphoria.  But it is clearly works on the same principle and used in the same way, so the descendant of the 1922 illustration.

So I will have to retreat on my statement that the Superlock is a Thackray washer, and fall back to the position of 'I don't know!'

I will forward on the old Buzzie website pages.

-Doug


Add 2nd Thackray clipping/advert. Upsize 1st Thackray clipping. 20Jan19, Doug
« Last Edit: 28 Jan 2019 at 00:40 by Doug »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #49 on: 23 Jan 2019 at 10:51 »
I have completed my audit of parts for Engine  #1

Thanks to all the help Ive received from the forum I now know and pretty much understand virtually all the parts on the parts list. There are just a few special parts that I havent got, and as yet dont know how to get them.

The parts on the Parts List that I cant identify are:

#912 Ball for non return valve (Crankshaft Group)
#766 Spring for non return valve (Crankshaft Group)

I did wonder if these were part of non return valve in the oil feed system

#5940 Anchor Bush in Crankcase Group
# Lock washers for studs in side case 7077 and 7078

The only other items are 10450, 10511,10841 and 10515 from the magneto group. But I suspect they are part of the magneto - which is currently away being refurbed by a specialist, who would sort all that out if they are.

My list of "Trickey" parts is mercifully short. The biggest issue are the Head Gaskets, which are re-usable copper rings. I have advertised for original ones, but dont expect any responses. So Im looking at having some made. Ive got a few irons in the fire. My first approach is to look at a welded wire ring solution. But it has also been suggested by a DT owner here in the UK to get them machined out of solid plate copper.

There are also a few parts to have made, but I have drawings for them now, and look fairly straight forward jobs. I have also obtained some bits off the shelf which has solved most of my other other trickey parts issues. Finally Doug is supplying me with the hardware I need to complete the build
 
So the next step is to make the parts I can make and do a dummy build. I plan to make some dummy head gaskets from card for this, so I can turn the engine over and check it all works according to plan, and check the lubrication system. This should finally identify any parts issues I have and no doubt give me a new To Do list!

Then its on to the carbs.......