Author Topic: DT/SW5 Engines  (Read 10403 times)

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Offline Buzzie

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Re: DT/SW5 Engines
« Reply #50 on: 23 Jan 2019 at 11:55 »
Doug

Those washers look fascinating! It forves the old addage that there is nothing new in this world!

I'm intrigued by the "Absolutely Foolproof" washers which sit on the outboard end of the bolt. Might be the answer to my drive shaft problem .....

Offline Doug

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Re: DT/SW5 Engines
« Reply #51 on: 23 Jan 2019 at 18:42 »
Douglas,

The K29 spares list if for the tall airbox DT, and that does not have the same oiling arrangement as the small airbox type. I have not seen an example with all the original hardware intact, but it does not have the 7/16-20 bolt with the one way valve. Given that a ball and spring are listed with the crankshaft assembly, that is where they must have put the one-way valve on the earlier models. Likely captive under the engine pinion bolt. I believe the 2-3/4hp side-valve models used a similar arrangement.

#5940 Anchor Bush in Crankcase Group. This is the insert that the engine clamp bolts threaded into. Rarely require replacing unless the engine mount has fractured. Note that the insert is clipped by the hole for the crankcase bolts.



#7077 Lock washers for stud (inside case)
#7078 Lock nut for stud (inside case)

These are for the idler stud. It is a bit of an odd arrangement. The nut is scotched on the inside of the case so it cannot turn. The idler stud is threaded into it like a bolt. That in turn has a keep plate to prevent it from unscrewing, so why is the lock washer fitted? I do not recall ever seeing a lock washer still in-situ, so it may be a thing that they stopped doing on the later engines. Or everyone figured they were redundant and omitted them. The term 'lock nut' in this case is a bit of a misnomer. It is not a self-retaining nut but just a plain, thin nut that the idler post threads into. It is not even what I would call a jam nut. I don't know why Douglas did not just thread the bronze insert cast into the case and screw the idler stud into that; after all they did have the keep plate to keep it from coming loose. They seemed to go to a lot of trouble to secure the idler stud! 

Cannot help with the magneto items. Over this side of the pond the original magnetos are long gone from the engine by the time I acquire them!

-Doug


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #52 on: 24 Jan 2019 at 11:16 »
Doug,

Thanks for the comprehansive reply as ever!

As I read the post I realised you had already given me information to the Oil Valve system and the idler stud issues in earlier posts, but I hadnt quite worked it all out. As I understand it now the oil system on my post K29 engine has oil fed by gravity into the internal pump through the oilway in the side of the airbox. Here it is pumped by the internal pump through the oil metering device to the second stage of the pump into the oilway in the timing chest and hence to the crank via the quil. However it was possible to hand pump oil direct to the crank through a second metering device on the tank. This required the oil flow to the crank to be controlled by a bypass valve, so that when the hand pump was operated the oil from it flowed into the crank, and the mechanical pump oil was bypassed to the crankcase. Otherwise the oil from the mechanical pump was directed to the crank. There is no valve arrangemen in the crank

On my engine I dont plan to use the manual pump. So I wont use the bypass valve, but instead plug the hole where it is mounted and plug the oilway where the manual pump was connected to the timing chest. This is to avoid the possibilty of loss of oil pressure due to the bypass valve sticking open.

I certainly should have picked up on the idler gear stud, because you have posted pictures of the stud, and the securing plate, the scotched nut and even sent me a drawing of the keeper plate! But its great to have the part numbers on my parts list linked to these items. It just squares the circle.

My engine #2 has some damage to the crank case around the mounting clamp area. It looks like it may have been adapted to another application. I have put all that to one side for the moment. But I think I may need some achor bushes, or something similar at some point in the future......

Offline eddie

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Re: DT/SW5 Engines
« Reply #53 on: 24 Jan 2019 at 12:15 »
Douglas,
               With the normal oiling system, there is only one oil feed from the tank to the timing chest, so DO NOT plug any of the oilways. You only need to replace bolt 'A' with a blank one that will not let oil back feed through it.

  Eddie.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #54 on: 24 Jan 2019 at 12:29 »
Eddie

Thank you for that important clarification! Its re assuring to know I have a Guardian Angel watching over me!

On a related point Im still undecided on which oil to use. Would you consider anything else other than Castrol M? Im considering a modern high quality fully synthetic oil......

Douglas

Offline eddie

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Re: DT/SW5 Engines
« Reply #55 on: 24 Jan 2019 at 12:43 »
Douglas,
               I'm a bit of a Luddite who tends to stick to the tried and tested - hence I still use Castrol 'M' in my methanol burning sprint engines. Modern synthetic oils may well be OK, but I have no experience of them to fall back on - and few of us these days, can afford to suffer a serious mishap, engine-wise!

  Regards,
                Eddie.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #56 on: 24 Jan 2019 at 13:19 »
Hi Eddie

Thanks for that response. You make a reallypowerful point, which has made my decision a lot easier!

I certainly cant afford a catastrophic engine mishap, so as I am intending to use Methanol fuel too, Castrol M it is!

Thank you!

Douglas

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #57 on: 24 Jan 2019 at 15:00 »
Look what the postman just brought!

Two unused spark plugs for my Engine, or at least engine #1. #2 will need somthing special.

Still in their boxes!


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #58 on: 29 Jan 2019 at 22:36 »
As you will have noted a few posts up this thread Ive decided to use Castrol M oil on my dope powered DT Engine , following some powerful comments to stick to the tried and tested.

So thats that I thought, until I tried to buy some! The only reference I could find on line was from a UK distributor who said that it is unavailable in the UK. I did find mention on a Kart suppliers site of litre bottles of "Racing M"  oil, described as a caster based two stroke oil for racing applications. Is this Castrol M, or another oil completely.

Does any one know anything about the current stuation with Castrol M. Can it be bought in other territories? Is there another make of vegetable based oil suitable for dope powered engines such as the DT Douglas engine?

Any comments, information or advice very much appreciated!

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #59 on: 01 Feb 2019 at 10:02 »
Work continues on engine #1. Its now moved to the workshop stage!

The crankcase is all assembled. Avit have arranged to have it inspected by a specialist they have used and who are going to make my head gasket rings. It will then be ready for the rest of the engine to be added.

I have cleaned all the rocker system components including the grease reservoirs and grease nipples, rocker arms, rocker shafts and steel bushes. They seem to be in pretty good condition with minimal play. They also fit snugly in the perches on the cylinder head, which are also in good order. These are all shown in the pic.

The wicks in the rocker shafts which transfer the grease from the reservoirs are missing, so I've made some new ones. I had thought they would run the length of the shaft, but there is a constriction about an inch in, so I assume they stop there and the grease lies in the shaft ready to flow out in between the shaft and the bush. I decided to leave some tails on the wicks so they were immersed into the grease in the reservoirs. I will trim them on assembly.
« Last Edit: 01 Feb 2019 at 11:49 by Buzzie »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #60 on: 01 Feb 2019 at 11:56 »
pic

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #61 on: 01 Feb 2019 at 12:39 »
Another piece of work ticked off..

Thanks to the help Ive received on here I now understand how the lubrication system, and slowly bit by bit I found the parts of the system that feed the oil into the crankshaft. So now I have assembled it in the timing chest.

The system is fed by a gravity feed from the tank into an oil gallery which is cast into the timing chest. From here it is pumped through a metering device to be pumped a second time into a sprung loaded quil device into the end of the crankshaft. The quill is made of brass and was pictures in an earlier post.

The only part I couldnt find was the spring, but armed with a drawing from Doug I made a copy from a bigger spring of the appropriate diameter and guage of spring wire. Also the leather washer was a bit tatty, and I managed to find a new one on eBay. I left the washer soaking in some R40 oil overnight. I then generously lubricated the oillway and inserted the assembly in it. It was a bit tricky, but I got there in the end. The quil can be pushed in with a finger, and it springs back out nicely as I imagine it should.

I then went on to test the pump. I poured a little bit of R40 into the inlet ports of the pumped. As I turned it over the oil primed the pump and some eventually squirted out of the outlet ports! Im happy that now Ive made a new gasket the pump is ready to be mounted on the timing chest too.

Thanks to Dave for adding the pics to this post for me.

Photos added 2nd Feb 2019 - Dave




« Last Edit: 02 Feb 2019 at 14:05 by Buzzie »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #62 on: 01 Feb 2019 at 14:59 »
The oil metering device referred to above is mounted on top of the timing chest. It comprises of a feed adjustable by a large metal dial and a drip nozzle, which can be viewed through a large glass window. This enables the operator to adjust the the rate of oil feed by observing the rate of drips from the nozzle.

The device was in filthy condition, and badly stained inside. I couldn't get inside without removing the glass, which was tightly jammed on. So I cleaned it, soaked the rim of the class in WD40 overnight before warming it with a hot air gun and unscrewing it with a pipe wrench.

I then cleaned out the bowl into which the oil drips with a Dremel and wire brush and painted it white before reassembling it, with a light light smearing of grease on the rims' threads.

Pic shows the device in pieces
« Last Edit: 01 Feb 2019 at 21:34 by Buzzie »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #63 on: 02 Feb 2019 at 15:16 »
You may recall that no sooner had I decided to stick with the tried and tested Castrol M caster oil to lubricate engine #1 than I found it impossible to find supplies. I contacted Castrol through their website. They responded by saying that Castrol M hasn't been made for many years, but recommended Castrol R40 as a suitable replacement.

I replied “I know Castrol M was formulated for use with engines running on Methanol. Will Castrol R40 be suitable for this application? The engine concerned (Dirt Track Douglas 500 twin) runs a total loss lubrication system, so the oil passes through the engine once before dissipating into the atmosphere...”

They replied “Yes R40 is suitable. It is used widely in similar applications such as Speedway JAP engines, Go Karts and RC models “

Im a little bit unsettled that I cant use the proven Castrol M, but there isn't any, so that's it. So I dug a can of R40 out of the garage and am using it to assemble the engine with. I plan to continue to use it for the series of pre start up tests I have planned. I will try to find fresh supplies before I use the engine in anger.

« Last Edit: 02 Feb 2019 at 15:45 by Dave »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #64 on: 13 Feb 2019 at 11:35 »
Things have been a bit quiet on the DT engine element of the Buzzie Project. This is because I'm waiting for some parts to arrive before final assembly can begin. So I decided to take advantage of this interegnum to take a short break from the engine and turn my mind to some of the issues I face with the Buzzie chassis.

However I have cleaned and prepared all the parts that I have to hand, and made all the gaskets I need to reassemble the engine. Apart from the headgaskets of course..... I havent managed to get the engine infront of the chap who is going to make them for me yet, and I cant reassemble the heads and valve gear until he's measured the grooves in the heads and cylinder barrels. Obviously I need the head gaskets themselves to do the final assembly of the engine, but I plan to use some card gaskets to enable me to do a dry assembly and set up the valve gear and engine timing. In fact I imagine three stages of assembly. The first stage will be to assemble the bottom end so the engine can turn over and I can test and fettle the lubrication system. The trial head assemby  stage two, and then of course stage three the final assembly to test compression and get the engine started!! So easy to say lol!

One thing that has moved on is the Magneto. I had an almost complete BTH Magneto which came with Engine #2, and it even prodced a spark, which I discovered when I gave myself a shock turning it over! However I dont want to be battling with a marginal mag when I put the engine in Buzzie, so I decided to have it refurbished. Unfortunately Paul at APL was unable to take new work on, so I had to look elsewhere. Tony Cooper in Halesowen is well recommended on local vintage bike forums, so I sent my magneto to him. He was easy to deal with, he stripped the mag and replaced some worn bits, rewound the armature and remagnetised it. He didnt do any uneccesary work and the cost was reasonable. I got it back in about three weeks. However I havent eaten the pudding yet to prove the work, but I am pretty confident it will be up to the job. I will attach some pics below.

I cant go much further yet, but Ive just received a card from the post office asking for the customs money on a parcel from abroad. It could be the hardware I need from the US, or it could be some spare domed top pistons from Canada. The parcel will be delivered on Saturday, so if its the hardware then I'll be off again!


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #65 on: 13 Feb 2019 at 11:48 »
Magneto Pic1


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #66 on: 13 Feb 2019 at 11:49 »
Mag pic 2


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #67 on: 16 Feb 2019 at 09:37 »
Things are starting to happen again! The parcel which I had to pay duty on ealier in the week turned out to be the pistons from Canada. These are a well used pair of pent top pistons without rings which I will put to one side ready to either act as spares for Engine #1, or as an option to go in Engine #2 when it is eventually built.

I attach a couple of pics of the pistons that have just arrived, and one of the other spare pistons I have, which is similar to the ones fitted in Engine #1. It is clear that they are different patterns. The latest arrivals are more "Chiseled" in appearance, whereas the others have a more curved pocket to accomodate the valves as they open. That they are different isnt surprising. There are mentions of all sorts of different compression ratios for DT5 and SW5 engines in contemporary documents.

The other piece of news is that when the postie brought the pistons, he also left a card asking me to pay some duty on another parcel, hopefully that will be the hardware! I managed to intercept the postman later on his round, and the parcel is ready for collection in their depot in Swadlincote. So all being well I'll have the bits later today :-)
« Last Edit: 16 Feb 2019 at 09:52 by Buzzie »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #68 on: 26 Feb 2019 at 22:29 »
Pic 1

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #69 on: 26 Feb 2019 at 23:35 »
Todays been a big day!

When you last heard from me I was on the verge of starting assembly and test. Since then Ive been working away preparing parts for assembly, doing trial assembly and finally getting ready for phase one of my test programme.

I removed one of the cylinder barrels with a view to fitting gaskets under the compression rings. However I was surprised to find that the company that had built the bottom end had fitted them, but as they'd used white paper I was unable to see them.. I replaced the one I had split and after having a good look round I put the barrel back on. I was greatly reassured by what I saw. The piston rings looked new, and were gripping the cylinder walls nicely. The lateral play in the conrods was minimal amd there was no measurable radial play. The conrods had been polished and everything was lightly lubricated. It all looked pretty good to be honest.

Using the nuts included in my hardware pack from Ohio I put the cylinderheads on the engine, without headgaskets at this time. I then fitted the oil pump to the timing chest using a new gasket. You will recall that I tested the oil pump earlier, and it worked well. I then fitted the oil metering/dripper unit to the timing chest, using the orientation shown in some pics of a DT which I took in the National Motorcycle Museum. I then fitted the timing chest to the crank case, rigged up a temporary oil reservoir and connected it to the oil input to the timimg chest.

I tried turning the engine over to test the lubrication system. The first stage was to see the oil being pumped up into the dripper, before it is metered and sent to the second stage of the oil pump and thence to the cranksaft to lubricate the engine. However I didnt get off first base as nothing apparently happened. Whilst still scratching my head about this I noticed I could see the pump drive gear through the magneto drive mounting. So I turned the engine over again, and noticed the drive gear wasnt turning. So obviously the pump wasnt being driven.

I removed the timing chest and coud see no reason why the drive gear wasnt engaging. I checked the mounting of the pump, and compared the pump and timing chest with the ones from engine #2. They looked identical, and I tried a few measurements which showed they were dimensionally similar. I tried refitting the timimg chest again few times to no avail. Then I noticed that the pump drive gear moved backwards and forward as the pump is turned over. I tried moving it to one end of its travel, and refitted the timing chest, and hey presto the gears engaged and the pump turned over.

I then turned the engine over much more quickly using an electric drill, but still no oil emerged from the dripper nozzle. I removed the plug from the inlet oilway and discovered it full of oil, so it had been pumped out of the reservoir into the engine. So I tried removing the dripper, and  found the oil was being drawn into the outlet port of the dripper. It was fitted the wrong way round, so obviuosly its orientation was different to the one in my pic! I turned it round and tried again.

This time after not too long the oil started to drip out of the nozzle and into the engine. I had opened the adjustment on the metering device to maximum flow to help things along! I turned the engine over with the drill a bit more, and then noticed that oil was slushing out of the hatch underneath where the magneto mounts. Closer inspection showed that oil was coming out of the big end bearings, and it was splashing all over the inside of the engine, and a pool was forming on the floor of the crank case. Job done, test phase one complete.

It may sound silly, but I was really excited hearing the engine turn over and seeing oil dripping steadily out of the dripper nozzle!

I'll attach a few more pics of the engine taken during this phase.....
« Last Edit: 26 Feb 2019 at 23:57 by Buzzie »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #70 on: 26 Feb 2019 at 23:59 »
And now its on to getting the valve gear sorted. Thats for another day, but here is a taster of how far I've got tonight!


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #71 on: 28 Feb 2019 at 22:29 »
I made a bit of a false start on timing the engine by trying to fiollow a procedure from the Douglas Handbook for the 2 3/4hp model, which I thought might get me there or there about. In fact it probably would have done, if Id known then what I know now, as the following tale will reveal!

Having failed to get engine #1 to turn over without something fouling using this method I decided to go back to first principles.; So I made up a timing disc out of cardboard and marked the valve and magneto timing points on it. My enegine has a 10.50.63. 20 cam in it so I marked those in red on the disc. Whilst I was at I also marked the points for the later 20 in cam in green. I made this disc the right diameter for the Douglas Flywheel and marked it by taping my normal Oselli disc to the card, and extending the markings out to the ouside edge of the card disc using a ruler. I attach a coupe of pics which illustrate this:


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #72 on: 28 Feb 2019 at 22:53 »
Armed with my timing disc I went out into the workshop and mounted it on the engine. I made up a pointer out of a thin welding rod and stuck the disc on the flywheel with some double sided tape. With the engine set up at TDC I lined the pointer up with the TDC mark on the disc. You can see this set up on the photo below..

Next step was to move the engine round to the "In open" mark on the timimg disc, and set up the camshaft so the inlet valve was just opening, and insert the cam drive gear. However when I tried turning the engine over by hand something was fouling. It was a soft sort of stop, so I didnt think it was the crank fouling on the cam lobes, so I deduced it must be a valve fouling something.

I suspected it was the piston because I'd made a mistake with setting up the timing. I reset it a few times, always with the same result. I had confirmed it was a valve by removing the push rod. So after much faffing about I thought it could only be the valve hitting the cylinder wall or the face of the cylinder barrel. Removing the head showed it was the valvehead hitting the face of the cylinder. There were clear witness marks on the valve and the cylinder.  These can be seen in the attached pic.

I compared the size of the valves with those in engine #2. They were visibly bigger. So meantime I fitted a head from engine #2 to the engine, timed it up again. Now the vaves opend and closed nicely, but then the crank fouled again. This time it was on the camshaft. Again I retried the timing setting, different means of inserting the drive gear but to no avail. Then I noticed I'd put the new head on the wrong way round, and so was timing the wrong lobes on the camshaft. This told me I was too tired to do any more good, so I came for the night!

So tomorrow Ill start nice and early and see if I can do the job properly now. Once thats done I'll turn my mind onto what to do about the valves ......


Offline Doug

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Re: DT/SW5 Engines
« Reply #73 on: 01 Mar 2019 at 04:05 »
Douglas,

I have seen cylinders with a small relief for the valves, but my assumption was it was something added later to fit oversized valves. Like in this example of a 600cc (68mm bore) cylinder.



I have seen plenty of 500cc barrels that didn't need them. The original inlet valves would be 1.484 inch diameter and the exhaust 1.422 inch.

-Doug

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #74 on: 01 Mar 2019 at 08:05 »
Hi Doug

Thanks for that info.

I had wondered about relieving the top of the barrels in a similar manner to that shown in that pic, so its interesting to see it has been done. I have used the technique on my racing MG engines, where it was common practice. I cut small pockets on the cylinder block face.  Obviously they couldnt be so deep as to go below the top piston ring. I always allowed a decent margin of error to allow for "stretch" in the conrod piston system and closing valve clearances.

I am in no hurry to get my die grinder out! Barrels are in short supply and once its done its done. It does also rather have a whiff of a bodge about it. The valves do appear to impinge into the land between the head gasket groove  and the combustion chamber on the head, although there does appear to be more meat on the corresponding land on the cylinder barrel. All this only became apparent late last night, so I havent yet had a chance to appraise the problem properly with some proper measurements etc. Those valve dimensions will be very useful then.

In the short term I plan to use the heads from engine #2 to at least get the engine running. These are fitted with visually smaller valve heads. I've fitted one on the engine and it turns over OK without any fouling. However they came assembled with valves, springs and valve gear and I haven't taken them apart to find out what sort of condition they are all in. I had always planned for a lot of fettling on the engine after it is running before using it in anger in the car.

A visual inspection of the original cylinder head which was fouling (there was only one fitted when this occured) gives the impression that the valves are standing more proud of the valve seats than on the ones from engine #2. They also look slightly bigger. As the valves are in place I can't yet see if the port diameter has been increased and new seats machined in. Im hoping that the seats are standard, and that machining a bit off the valves will get them sitting lower in the head and solve the problem. Well I can dream cant I?

Now off to the workshop. I'll keed you all posted!

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #75 on: 01 Mar 2019 at 17:37 »
Back into the workshop for a morning of head scratching and discovery with the timing issues.

Just to recap. I was timing the engine by putting on the rear cylinder head and timing the valves for that cylinder. After that all things being equal the front cylinder head should be fitted and everything would be adjusted ......

First up was the removal of the head from engine #2 which I had fitted last night when I discovered that the cam lobe to fouled the crank preventing the engine turning. Or so I thought. I realised last night that I'd fitted the wrong head, so the ports were on the wrong side. So fresh this morning I fitted the correct head on the rear, with the ports now on the correct side. Confident all would be well . I turned the engine over, and on its second revolution a cam lobe fouled on the crank.... If you havent worked on these engines by the way its near impossoble to see whats going on in the crankcase.

Double checking everything I came to the conclusion it could only be a timing issue, so I tried slightlydifferent timing settings, to no avail. I reasoned that as Id got the timings from a Factory Document, and the same timings wwere stamped on the cam they must be more or less correct. Then it dawned on me that if the engine was rotating the other way the timings would be different. But surely all engine flywheels turn clockwise right? Thats why timing discs are always marked for clockwise rotation isnt it?

Yeah I know, everyone knows thats not the case with Douglas Engines. Well nearly everyone. I found a video clip on Google of a chap starting up his DT. Well at least there was no doubt about it, the enginge should be turning "backwards". So I reversed the timing markings on my disc, retimed the rear cylinder and Bobs your uncle! I then put on the forward cylinder head with its valve gear, and it all timed up perfectly.

Next up I fitted the magneto using a very simple procedure described by Eddie Turner on a thread on here on timing the 600 OHV engine. A quick check showed the timing was pretty much bang on! So I connected up the HT leads to some plugs and turned the engine over with my drill, and enjoyed the specatacle of them sparking away where they lay on top of the engine. So now she's all ready to be started when I've sorted out the carbs found some way of sealing the cylinder head to the cylinder barrel.

So for now I have fitted the cylinder heads from engine #2. I'll come back to the issue of the apparently over sized valves at a later date and decide which heads to install when the engine goes into Buzzie, and how to complete engine #2 when all thats done. For now the assembly and pre start up testing is complete.

Here are some pics of the engine undergoing its tests.

Offline Doug

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Re: DT/SW5 Engines
« Reply #76 on: 01 Mar 2019 at 19:20 »
Douglas,

In theory the conrod cannot hit the camshaft:



While the camshaft does overhang the eye of the conrod slightly, it is only at the edge where the eye does not project beyond the rib of the center web. Even if the cam were miss-timed so that the camshaft lobe coincided with the throw of the crankshaft, they would still clear by 1/32 of an inch. This is if everything is as it left the factory.

Things that can upset the apple cart are camshafts with lobes that have been welded up to increase the lobe height. Grinding some off the base circle, which is the normal way to increase cam lift, would not affect the clearance issue. Shifting the camshaft sideways (off center) so it started to impact the rib on the conrod eye. Or fitting non-standard rods that had a bigger eye or the rib(s) were wider and transgressed the path of the cam lobe.

-Doug

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #77 on: 01 Mar 2019 at 20:10 »
Doug,

Thats a bit unsettling! The problem is that I just couldnt see exactly what was happening. But it looked/felt like the cam on the crank. But it could have been something else. It may have been a valve but didnt sound/feel like steel on ally piston.

It could be a built up cam. Its a better solution than undercutting the base level.

Whilst I didnt specifically check the lateral alignment of the cam I think the cam followers were running on the centre of the lobes. But I will double check, and also see if there is any end float on the camshaft.

Ive not seen the conrods out of the engine, and of course I have no idea of their provenace. However if they dont actually touch anything I suppose it can do no harm if they are oversize?

Offline Doug

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Re: DT/SW5 Engines
« Reply #78 on: 01 Mar 2019 at 20:59 »
Douglas,

Pull the magneto and lift the inspection plate from the top of the engine. You will be able to verify cam to tappet alignment and see if the cam lobe is actual fouling anything in the camshaft area.

There were a few style of conrod forgings used by Douglas. Two lengths and various amounts of radius between the beam and the bigend eye (more radius as time went on). However all of them have the same outside dimensions to the bigend eye, so none of them had a greater or lesser impact on the cam lobe clearance.



At the top is the 'standard' DT conrod; by far the most commonly seen. The next one is one created initially for the short-stroke DT (68mm), c1931-32. Those did not perform particularly well so the conrod forgings were used in the 82mm stroke 1934-35 ohv road models with a shorter cylinder and piston. I believe they were also used in the F/G31-32 models that had the top end carry over into the 1934-35 ohv models. They were also used in the 500cc side valve Blue Chief and 500/600 Aero, and this is actually a conrod from one of those. When used in an ohv engine, they would machine more materiel away from around the little end, just like the conrod below it. The rod at the bottom was developed at the nearly the same time, note the consecutive experimental numbers. It is a pretty rare rod, and seems to have been a late addition for continuing on with the long-stroke (82mm) engines and trying to keep them together. This last rod is probably too well filleted as Douglas ohv crankshafts seem sensitive to too much mass. You want to keep it as light as possible without it blowing up; a fine balancing act! The crankshafts are not terribly rigid, so excess reciprocating mass just invites problems.

-Doug


Offline Buzzie

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Re: DT/SW5 Engines
« Reply #79 on: 01 Mar 2019 at 22:10 »
Doug

I timed the valves and did all that anti fouling work with the magneto off (I haven't fitted the cover underneath it yet). Thats a very useful little spy hole because you can also see if the oil pump is turning how the lubing is coming on. I'll whip the magneto off again in the morning and check the cam alignment and the end float. I think I might be able to measure the camshaft base circle diameter through that hole. Even with magneto off and a small led lamp inside the crank case I just couldnt see what was touching what. The action was going on under the timing side of the crankcase top. Of course they are not touching now, so nothing to see.

I attach some pics of my spare conrods. The first one is one of a matching pair from engine #2, the second and third are odd ones I bought on ebay. They all look to me like the common ones you refer to. I saw the conrods fitted to this engine when I took the cylinder barrels off, and I have the impression that they are the same as the others.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #80 on: 03 Mar 2019 at 21:45 »
Todays trials and tribulations!

Read more on next post!

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #81 on: 03 Mar 2019 at 22:37 »
The engine is now complete and ready to be started. The carbs have been fitted, an under magneto inspection carried out, the valve clearances set and the valve and ignition timing set. So why wont it run? TBH I'm hoping some of you might have some ideas!

To put some meat on the bones. My inspection of the camshaft etc showed that there was no significant end float on the cam and the cam followers seemed to be running in the centre of the cam lobes and the cam drive gear was meshed in the middle of the idler gear. I couldnt make any meaningful measurement of the cam base circle though.

I timed the valves using my 360 deg timing disc on the flywheel rotating anti clock wise looking at the flywheel, so the inlet just starts to open at 10 deg BTDC. I timed the ignition so that the contact breaker is just opening at 37 deg BTDC on the front cylinder with the rear cylinder valves "rocking"

The magneto has contact breaker base plate marked with a cast L. The magneto rotates clockwise when the engine turns anti clockwise. The stud is opposite the front cylinder. I am not certain that the slip ring is the correct one, but it was recently professionally refurbished. This set up is pictured in the photos posted below.

Both spark plugs had good healthy spark when the engine was turned overtuned over with the plugs removed. The plugs are one NOS Champion COM6 and one used Champion COM5 cleaned and regapped. The gaps are around 12 thou. The contact breaker points gap is 11 thou fully open, and the opening point found when a 2 thou feeler gauge between the points is released.

The engine is running on methanol. The carbs are AMAL/AMAC type M's (I think). I have cleaned, readjusted them and blown through all the various orrifices. Everything runs freely in them, The jets are 150 front, 140 rear and the engine is fitted with domed topped pistons. CR measures at 10.1

When the engine is turned over with the plugs fitted I get good compressions in both cyliders, and I can see vapour being blown out of the exhaust ports. Apart from the occassional lone cylinder firing the engine wont start. I am turning it over anti clockwise with an electric drill on the flyweel nut. I have tried spraying Bradex Starting fluid and putting small amounts of methanol into the combstion chambers through the plug holes (on seperate occasions). Ive tried advancing and retarding the ignition at the magneto, opening the throttles. All to no avail!

I attach below a couple of pics of the magneto. The first one is of the engine at TDC with the rear valves rocking.

Offline eddie

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Re: DT/SW5 Engines
« Reply #82 on: 04 Mar 2019 at 07:51 »
Looking at the photo of the points end of the mag, if the valves on the rear cylinder are 'rocking', the mag needs retiming so that the points are to the left (that is, I think you have it timed on the wrong cylinder). An easy check can be done by removing the front HT pickup to see if the slip ring  brass segment is visible. Also, if you are running it on methanol, you will need much larger jets (and slides with a smaller cutaway than those used with petrol). To give you a guide, our sprint engines run 600 - 650 Amal main jets with 1" bore carbs, and about a no.2 cutaway. Methanol is very tolerant of rich settings (provided you have a good spark) but weak settings can quickly cause piston damage - so be careful!

  Regards,
                  Eddie.

  P.S.  When you set the valve timing, did you also check the point at which the valve closed? The reason for asking is that some manufacturers quoted timing figures obtained with increased tappet clearances because some ramp cams are difficult to time accurately at the start of their lift. You may need to experiment to get the factory figures.
« Last Edit: 04 Mar 2019 at 07:57 by eddie »

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #83 on: 04 Mar 2019 at 21:20 »
Hi Eddie,

Thanks for that info. I turned the ignition timing round so to speak as you described. The engine fired on the rear cylinder about 5 times with plenty of oil smoke before stopping. I didnt have time to do any more today, but I think thats a step in the right direction.

Thanks for the warning about weak methanol mixtures. I am interested in the units of measurements for jet sized. Ive seen some Douglas data which says the jet sizes were 100 to 120 for petrol and 35% larger for methanol. I assume that the numbers stamped on my jets are the same units as these ones, but have no idea how those figures relate  to the hole size, or whether the sizes you use are on the same scale, and what sizes these hles are?

I didnt check the timing of the valve closing point, but will do so tomorrow, I also plan to double check everything again and get the engine running properly, At this stage I only plan to get it idling. I will need to get some proper head gaskets made and then fettle it to start producing power and then put it in the chassis when it comes back from Avit with its mounting kit installed.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #84 on: 05 Mar 2019 at 20:48 »
I have the impression that the root of the engine running problem is the carburettors.

I checked the valve timing, it was indeed all over the place. So I changed it to bring the valve opening and closing points to within pretty much the same distance of the declared factory specs. I also retimed the ignition, cleaned the plugs and rechecked that both plugs are sparking when the engine is rotated. I then put the plugs in and tried to start it.

No sign of life, and plugs completely dry. It would run for a few firings on both cylinders when I squirted Bradex into the carbs, but thats all. I decided to try it on petrol, but my drill failed before I could I could try turning it over.

So apart from buying a new drill I think my next move will be on the carbs. Despite having an Amal manual and quite a bit of info on here I cant really be sure which carbs I have, or see anything obviously wrong.

I think I'll start a new thread about my carbs, to get my mind around the problem

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #85 on: 27 May 2019 at 22:12 »
They say no news is good news. Well thats not quite the case with my DT engine! In this case its just no news is nothings happened. However I thiought I should pop on here to say hello!

Work came to a dead stop because I can no longer turn it over with my drill. After checking all the settings, and putting some petrol in the carbs it fired a couple of times then stopped. When I tried to restart it it kicked back and broke the drill. I tried a bigger one and it broke that too. So I decided to draw stumps for now.....

The car has gome up to Avit to have the engine and gearbox sub frame made. This seems to be taking some time, but my plan is to wait until the work is complete and I can then turn it over by turning the rear wheels. The engine turns over by hand with the plugs out and the compression is fine when I turn it over with a socket and the plugs in.

So when the car eventually comes back I'll get back on the case and keep you all updated!

In the meant time Ive been to the Douglas Cavalcade and met some DT owners and their bikes, and also to a 500 Club Race at Oulton Park and saw the competition in action. They were very impressive with a decent sized grid. Ill attach a couple of photos


Offline roger h

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Re: DT/SW5 Engines
« Reply #86 on: 17 Aug 2019 at 21:57 »
As others have already said, this saga is the best thing I've read for a long time! Please keep it up.
I've just managed to get hold of an SW5 kit, so am very interested in all the chat. My bike will be used on the road, with perhaps a sprint or two! Regarding Dougie engines fitted to racing cars, don't forget that the late Kenneth Neve built a few specials, the first, pre war,  used two DT engines in a GN chassis, then he went to a single DT engine at the start of 500 racing post war. His last special, using two Ariel square four engines in a GN chassis, still races today. His book "A bit behind the times" is a good read. Best of luck with the motors, and with Buzzie,Douglas,  and very many thanks to Doug and Dave for your incredible knowledge and brilliant comments.
Roger

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #87 on: 15 Nov 2019 at 08:54 »
Its been a while since I last posted an update on here.

Unfortunately Buzzie with her Douglas DT Engine didnt get to race at the Goodwood Revival in September. We had hoped that we would get a late entry if someone withdrew. We were at the top of the reserves list but no one pulled out after the test day at Goodwood. Avit were preparing several other entries for Goodwood, including a1936 Maserati 6cm Grand Prix car, see pic below. So naturally they concentrated on getting these cars ready and work on Buzzie temporarly stalled.

Ive been up to see her since then, and met with Ewen from Avit to agree the way forward. The engine is ready for installation in the car. It has had to have a new flywheel made because the Douglas one I provided is too great a diameter and fouled the floor, and more critically the primary chain gears didnt line up when the output sprocket and the secondary chain lined up with the sproket on the back axle. That position is set by the structure of the car, as is the position of the engine, so the flywheel sprocket had to move! Incidentally I suspect that Buzzies floor originally had a slot cut to provide clearance for the Douglas flywheel. You can't see the floor in the surviving photos, but the flywheel looks like a standard Douglas one. Obviously the new flywheel needed to have its shaft taper and keyway to match the Douglas crankshaft.

The new aerofoil shaped tank is complete. It has two compartments, one for petrol and the other for the oil. It has a 20 litre fuel capacity to allow for the high fuel consumption of the alcohol powered engine. The car should be able to complete a 20 minute race without issue. We have decided to install the kick start of the Norton gearbox so the engine can be kick started when the starter donkey engine isnt available.

As part of my Goodwood preparations I repaired and serviced the donkey engine I mentioned earlier. This is a trolley mounted Briggs and Stratton 8HP engine which turns a small roadwheel. The tyre on this road wheel is pushed up against one of the rear wheels to rotate them, and hence the engine to start it. The rear wheels are obviously jacked off the ground!

The plan now is to have Buzzie up and running to compete in some 500 OA events next season, so we can have more relaxed preparations for the next 500 Race at Goodwood, which is likely to be in 3 or 4 years time. I feel that with a decent competion record over the next couple of years Buzzie is much more likely to get an invitation to the next 500 Race at Goodwood.

In the meantime I thought I should have a Douglas to ride, and during a recent visit to Chris Wright to discuss my 2 3/4 HP project he very kindly showed me his wonderful collection of Douglas's of all eras. I was very taken by his Dragonflies, and when one came up on eBay a few weeks later with limited interest I bid, and won it at a very decent price. I collected it last weekend and rode it around some local sights as soon as I got it home. It runs very nicely and I think Im going to enjoy it. I have insured it so I can ride it to work if the notion takes me! It does need a minor frame repair, so if anyone knows what grade of steel its made of I need to know so I can get it welded up.
« Last Edit: 15 Nov 2019 at 09:02 by Buzzie »

Offline eddie

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Re: DT/SW5 Engines
« Reply #88 on: 15 Nov 2019 at 12:24 »
As I understand it, the early Dragonfly cycle parts were manufactured by Earles Engineering. The frame and forks were made from cold drawn mild steel tube but problems were encountered with the front forks, so the specification for the fork tubes was upgraded to Renolds 531 tubing.

  Regards,
                 Eddie.

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #89 on: 15 Nov 2019 at 12:50 »
Hi Eddie, helpful and speedy as ever! Thank you for the info, just what I needed to know. Luckily it's the frame and not the forks I need to get repaired, so it should be pretty straight forward. I understand that 531 is a bit tricky to mig or Tig weld so glad to be avoiding that!
Thanks again,
Best wishes, Douglas

Offline Buzzie

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Re: DT/SW5 Engines
« Reply #90 on: 30 Nov 2019 at 23:19 »
Well some fantastic, but challenging, news! The letter pictured below arrived this morning!

Having missed out on the Goodwood Revival it turns out that they are holding the first ever 500 race at the Members Meeting next spring, - and Buzzie has been invited!! This is just great news, because racing at this meeting will get Buzzie well known in Historic racing circles, and increase our chances of being invited to the Goodwood Revival next time they stage a 500 Race

So instead of a leisurely winter gently fettling Buzzie and her DT Douglas Engine, we have to work purposefully over the next few weeks if we are to meet my target of testing in January!

No doubt there are a few workshop and track adventures ahead, so stay tuned as I'll tell you all about them on here!
« Last Edit: 30 Nov 2019 at 23:26 by Buzzie »

 

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