Author Topic: 1928 EW ignition timing (Read 17787 times)

patrickhowell · « **on:** 19 Dec 2015 at 11:54 »

I'm struggling to set the ignition timing on my restored engine. At what point in the firing sequence should the points be fully open (I'm aware of what the book says, or rather, does not say)? The book also says set the points gap at no more than 11 thou, whereas my magneto restorer says 15 thou, with the advance / retard just backed off a bit from fully advanced. Also, I assume that being a 180 degree twin, it doesn't matter on which cylinder the timing is done, as the other cylinder will automatically be timed correctly?

oily bloke · « **Reply #1 on:** 20 Dec 2015 at 07:59 »

Hi Patrick,
I use a degree wheel mounted on the flywheel and I locate TDC on the front cylinder by taking out the inlet valve cap and visualy watching the piston rise on compression stroke. Set zero marker on disc. Back up beyond 50 degrees and bring forward to desired timing. Set timing wheel. Rotate a few times and re check. I use one of those electronic gadgets that lights up at the point of opening of the points but a fag paper will do just as well.
I set the gap at 12thou. The points open at 50 degrees before TDC on the compression stroke, mag fully advanced.
It is irrelevant when the points are open or closed so long as they 'break contact' at 50 degrees. It matter not if your timing is out by a degree or two. It makes little difference on these engines.
So long as you have the correct cylinder timed to the relevant HT output on the mag you should be OK. There is no wasted spark so you need to work out what cylinder you are firing. You can be 180 degrees out thus firing both on exhaust stroke.
You can, once the front is timed, check the timing on the rear cylinder using the same process. This ensures they are both firing at 50 degrees. Small adjustments can be made to equalise them.
Hope that helps.
Andy

patrickhowell · « **Reply #2 on:** 20 Dec 2015 at 14:33 »

Thanks, Andy. With no wasted spark, presumably if I have mistimed the ignition on the 'wrong' cylinder, swapping over the ignition leads to the other cylinders will cure the problem? When the points are just opening, how can you tell which ignition lead is about to fire?

oily bloke · « **Reply #3 on:** 20 Dec 2015 at 15:38 »

Hi Patrick,
Swapping leads may cure it.
You can tell which lead is about to fire by removing the HT brush holder on the mag and the one about to fire is the one with the conductor strip on the slip ring visible.

patrickhowell · « **Reply #4 on:** 28 Dec 2015 at 14:53 »

Thanks, Andy, I am learning all the time. I am a bit puzzled by the 'no wasted spark'. The magneto drive pinion has the same number of teeth as the crankshaft pinion, hence we get two sparks per revolution of the crankshaft and magneto. That suggests that each cylinder receives two sparks per four strokes, and therefore there must be a wasted spark. Where am I going wrong in my train of thought?
I put a multimeter over both sides of the points when open, and both sides are going to earth. I am more familiar with coil ignition systems, where that certainly should not happen. I note you use a lamp, so where do you connect it? Again, where am I going wrong?
Does your magneto have a screw holding the two-eared drive dog to the magneto shaft?
Again, many thanks, Patrick

oily bloke · « **Reply #5 on:** 29 Dec 2015 at 18:21 »

Hi Patrick,
The Mag runs from the inlet cam pinion which is a 'half time' pinion driven from the crank and fires each cylinder every revolution of the cam pinion.
The cam pinion is half the speed of the crank and the Mag fires every 180 degrees of its revolution but not both plugs at the same time.
Fore then aft. It effectively fires every 360 degrees of crank revolution but the slip ring directs the spark front then rear.
Hope that makes that clearer. I nearly confused myself!
My mag has a pinion the same size as the cam pinion attached to the armature nose with a nut.
Andy

oil baron · « **Reply #6 on:** 29 Dec 2015 at 19:25 »

Hi Patrick

See the attached diagrams taken from the 1926-30 350cc Manual, which can be downloaded from the barnstormers.co.nz website, might clarify the situation.
If the magneto ran at engine speed then there would be a wasted spark, because of the cam wheel and mag wheel are the same size it would mean that the valves would opening and closing every revolution, which is not how a four stroke cycle operates.
A point to note that in timing the magneto, that the magneto MUST be rotated in the direction of rotation of the Magneto to get the points just opening as the brass segment on the slip ring comes into view, because if the magneto is rotated the wrong way you can time it up with the heel of the cam opening the points rather than the toe of the cam. It would appear that although the timing looked correct the motor probably won't start - been there done that - it was a mag built up of bits and of course I went by the arrow engraved on the magneto - should have checked! you live and learn.

Cheers Steve L

Alan Cun · « **Reply #7 on:** 30 Dec 2015 at 09:20 »

Just a few points on EW Mags. The correct mag for EW is M2W2 with an external cable advance. The points block should show R for right rotation. L points blocks are on some OHV models. The brush ring should have a brass segment which are also R and L and you have to have the right one, Single BTH mags have a central segment, and EIC have a continuous full circle brass segment. If you are brave enough to strip a magy be sure to remove safety screws above and below pick up segment. If you do strip and find the windings soft and weeping its time for a rewind, otherwise the leakage will cause overheat and mag seizure.

If you have a second armature I have a simple method of testing by laying the bare armature on an ally channel with a screw pointing towards the brass segment. With the points screw inserted just earth a 1.5 volt to the ally and tickle the points bolt with a live wire and observe the spark.

regards Alan

patrickhowell · « **Reply #8 on:** 31 Dec 2015 at 14:19 »

Thanks for all your comments, chaps. You are entirely right about the mag pinion running off the inlet pinion, both have 40 teeth, while the crankshaft pinion has 20, so obviously the mag is running at half crankshaft speed. Now I understand.
What I can't understand is why the overhauled engine will not fire, not a single bang. Before overhaul, it was running, but the BTH mag broke down, and was overhauled, and now produces a good spark, with the points set at 12 thou. New big and small ends, and new Honda 4 pistons, with a thin plate below the cylinder bases to bring the piston crown height down to the old piston measurement. Valves and seats were refaced, with tappet clearance set at 6 thou. New spark plugs, set at 25 thou. Valve timing set as per the book, and rechecked. Ignition timing set with the points starting to open at 45 degrees BTDC, and rechecked. B&B carb delivering fuel, though leaking. Ignition retarded, choke closed, and throttle cracked open for starting attempt. I'm interested in the comment about intermingled parts; presumably the suggestion is that the mag should be turning clockwise as you face the points, notwithstanding the arrow pointing the other way?
I don't have much more hair to pull out in frustration, I even swopped the plug leads over, in case I had made a fundamental mistake. I'd welcome some enlightenment, or if any member with experience of the EW lives near Stratford-upon-Avon, I'd love to hear from them. A Happy New Year to you all.
Patrick, 01789 773801

oily bloke · « **Reply #9 on:** 31 Dec 2015 at 17:17 »

Hi Patrick,
I am in Surrey so a bit of a trek but you are welcome to come to me and we can put it on the bench and see.
Is it possible you timed the bike on full retard? The 50 degree full advance works. Have you got an in situ spark? Could you have an air leak at the inlet manifold/cylinder joint? Is the carb delivering fuel to the manifold. Are the Cams timed ok?
Feel free to PM me if you want to visit or chat.
Cheers
and Happy new Year
Andy

eddie · « **Reply #10 on:** 31 Dec 2015 at 17:31 »

Patrick,
From your last posting, I think you may have timed the mag wrongly. From the flywheel side of the engine, both the flywheel and the mag should rotate anti-clockwise. With the normal BTH set up, the actual points face the cylinder that is firing - that is, with the points roughly at 9 o'clock, the front cylinder is firing. Also, unlike electronic ignition, mags don't like excessive plug gaps - 15/18 thou is the usual recommendation. You may also be having problems starting it if you are fully retarding the mag - try again with only half retard.
Regards,
Eddie.

patrickhowell · « **Reply #11 on:** 01 Jan 2016 at 10:57 »

Eddy
My BTH mag rotates anti-clockwise too, but the points are at one o'clock at TDC front cylinder, hence they are pointing more towards the back cylinder, contrary to your machine. I have verified this by the position of the brass slip ring segment, which leads to the front cylinder in that position. An induction pipe leak is a possibility, how should this be sealed? A very manky-looking O ring came off when I dismantled.
Andy, I timed it on full advance, ie, with the slip ring moved as far as it would go anti-clockwise, which is where the spring takes it anyway. Thanks for your kind offer to assist, where in Surrey do you live? I used to live in Dorking.
Patrick

oily bloke · « **Reply #12 on:** 01 Jan 2016 at 11:43 »

Hi Patrick,
I live near Woking. Just down the road from Dorking.
I used square fire caulk. Used to be an asbestos product but is now a graphite impregnated glass fibre, extruded into a square section of about 3mm.
I coat it with fire gum or similar, form into a ring and set around the manifold and gently clamp down with the locking ring being careful not to allow it to turn as I am tightening. Its been on for a couple of years now and has remained leak free.
The points heel should trail as apposed to leads.
Andy

eddie · « **Reply #13 on:** 01 Jan 2016 at 13:54 »

Patrick,
If the mag rotates anti clockwise, then the points cam is fully advanced when it is moved clockwise (against the rotation of the mag). From your last posting, you have timed it fully retarded, and that is probably why your points are opening at 1 o clock and not around 9 o clock.

Regards,
Eddie.

patrickhowell · « **Reply #14 on:** 01 Jan 2016 at 14:25 »

Eddie
If you are right, it would explain everything. I had always assumed, probably from what I had read, that pulling the advance/ retard lever towards you was retarding the ignition. I see now from the handbook diagram that the diagram shows the lever fully forward for starting, which I assume is in the full retard position. Can you confirm that opening the lever towards the rider is fully advanced, and vice-versa?
If so, I hope to have a Eureka moment tomorrow!
Andy, thanks for that, I'll see if I have that Eureka moment, and then look at the induction system.
Patrick

eddie · « **Reply #15 on:** 01 Jan 2016 at 14:53 »

Patrick,
There are many variables with magnetos and their advance/retard cables. As I said previously, if the magneto runs anti clockwise at the points end, fully advanced is with the cam rotated clockwise - so try operating the handlebar lever and establish which direction gives full travel clockwise - that will be fully advanced. If you were under the impression that the cam should be turned anti clockwise, you will have timed the mag incorrectly, and it will be necessary to pull the pinion off the taper to reset the timing. You say the mag gives a good spark, so with the timing correctly set, first kick starting should be the norm with the advance retard set about midway (not many engines run on full retard, and it is often used as a convenient way of stopping the engine if a cutout is not fitted).

Regards,
Eddie.

patrickhowell · « **Reply #16 on:** 02 Jan 2016 at 14:22 »

I retimed the mag as suggested, but all I got was a single explosion in the silencer. That and the fact that the plugs were slightly wet suggests that fuel is getting through, and the mag is working. I'll have a go at the inlet manifold next, did you use any O ring, gasket or material other than the fire caulk/ fire gum, Andy?

oily bloke · « **Reply #17 on:** 02 Jan 2016 at 16:33 »

Hi Patrick,
Some progress then.
I used the extruded material and the fire gum as described in my previous post. The fire gum simply acts as a seal between the extrusion and the lock ring and provides some lubrication during assemble so the extrusion stays put.
Whatever you use, it needs to be able to withstand the heat from the head so rubber, neoprene, silicone, instant gasket etc. Cannot be used.
Andy

patrickhowell · « **Reply #18 on:** 03 Jan 2016 at 13:16 »

Andy
The only caulking I ever heard of before was that used to cure leaks in clinker built boats. I guess this must be something to do with fireplace installation? Any idea where I might be able to get a small quantity?
An engineer friend suggested a silicon O ring as an alternative.
BTW, I am curious to know why the spark plug hole, which is 18mm, only has a 23/64" (9.128mm) hole at the bottom end. Surely there would be better combustion if the hole were full size all the way down?!
Thanks, as ever,
Patrick

oily bloke · « **Reply #19 on:** 03 Jan 2016 at 16:14 »

Hi Patrick,
try this link;

http://www.ebay.co.uk/itm/Stove-Rope-and-Glue-option-for-Wood-Burning-Stoves-Door-Glass-Fire-Seals-/111550178459?var=&hash=item19f8e8a49b:m:myI8wshSfsM6k69qiHxadCA

I cannot find the source of the stuff I have but it should do the job.
The O ring you describe cannot take the heat of the engine.
The small hole for the spark is, I believe, to help reduce fouling of the plug and accounts for the 50 degree advance. It is likely that combustion would be improved but I would be loathed to take a perfectly useable barrel/head on a one way ticket.
I think this is discussed elsewhere in the site.
Cheers
Andy

eddie · « **Reply #20 on:** 03 Jan 2016 at 16:55 »

Hi Patrick,
As Andy says, the small hole is to shield the plug and reduce the possibility of fouling from the fuels and oils that were available in the 1920's. For touring use, I would leave it as is - any modification could result in the need to experiment with the timing.
With regard to the sealing of the inlet pipe - Mr Douglas fitted Viton 'O' rings to the cylinderhead end of the inlet pipes on the Dragonfly. I have used them on the inlet pipe on my 2¾ without any problems. They are available from most bearing stockists. In your case, they will be squeezed down by the gland nuts, so may push out to a larger diameter - to overcome this, it might pay to use a slightly undersize 'O' ring (say 15/16" bore on a 1" pipe) to reduce the chance of a leak between the pipe and the 'O' ring.

Regards,
Eddie.

patrickhowell · « **Reply #21 on:** 06 Jan 2016 at 15:24 »

Thanks, chaps.
In fitting the induction manifold to the inlet ports, there are two metal pieces (one a side) between the manifold nuts and the inlet ports. Does the flange butt onto the port, or the back of the nut? Either way seems to have a sort of logic to it!
Patrick

oily bloke · « **Reply #22 on:** 06 Jan 2016 at 15:52 »

Mine bears on the back of the nut and squashes the gasket into the conical port

Doug · « **Reply #23 on:** 06 Jan 2016 at 22:37 »

An illustration of the same:

-Doug

eddie · « **Reply #24 on:** 07 Jan 2016 at 06:15 »

Doug,
Should the flanged collar not be the other way up - with the spigot in the gland nut. The packing would then be squeezed to seal in 3 directions - against the face of the collar, onto the diameter of the inlet tube, and into the conical recess. With the collar as shown, there is still the possibility of a leak between the collar and inlet tube (if the packing compresses thinner than the depth of spigot).

Regards,
Eddie.

patrickhowell · « **Reply #25 on:** 07 Jan 2016 at 15:12 »

I would have been inclined to agree with Doug, but for the fact that the inlet port is tapered like a valve seat, and the neck of the collar does not go fully home into the port. The other way round, as Eddie and Andy have it, is a much better fit. I am a bit hesitant about the exhaust gum, however, my first attempt left quite a bit of residue in the inlet port, and left a few bird droppings to fall into the cylinder, but that may hay have been due to a ham fist.
Patrick

Doug · « **Reply #26 on:** 07 Jan 2016 at 16:23 »

Eddie, Patrick,

As I remember, the collar did not fit very well through the gland nut on mine and tended to bind because the nut and the tube were not perfectly aligned. So I presumed with the collar down (which is how it came apart on my F28/600EW), it allowed a generous gap between the gland nut the inlet pipe. This allowed the gland nut to be aligned and threaded on to the stub freely, yet prevented the packing from extruding out that gap. If the collar were to extend all the way down into the conical seat, then that would be a problem as it would prevent the packing from sealing against the tube.

Having said that, I just looked at a spare 350EW engine that I acquired and the collars project through the gland nut! In that orientation, there is more packing in contact with the tube, and the collar acts as a thrust washer as well as filling up the gap.

Messieurs Douglas are quite on the orientation! Or, I cannot recall an illustration in a handbook for the EW era onward. It may have been common knowledge from the 2-3/4hp era. Perhaps a period photo will turn up where one can see enough detail as to how the factory did it. I would say if your inlet manifold aligns well with the cylinder stubs, assemble the collar with he flange through the gland nut. That will maximize the sealing area. If there is an uneven gap between the gland nut and the tube that you cannot eliminate, then try the collar with the flange down.

-Doug

Doug · « **Reply #27 on:** 07 Jan 2016 at 16:27 »

Wait, stop the press!

In the later EW handbook, there is a illustration of the B29 engine and it clearly shows the collars producing up through the gland nuts. So that is how the factory intended it.

-Doug

patrickhowell · « **Reply #28 on:** 08 Jan 2016 at 14:57 »

That seems to resolve the induction problem, but I'm now back to the timing. Just want to check I'm not doing something fundamentally wrong, so
1. Valve timing. Am I right in thinking that if the valves in the front cylinder are correctly timed, then those in the back cylinder must automatically be correctly timed also?
2. As it is a 180 degree twin, then TDC on the power stroke on the front cylinder will be TDC on the exhaust stroke for the back cylinder, and ignition on each cylinder will be 180 degrees apart . If that's right, then I wonder why the front cylinder appears to be in the firing position with the points at 9 o'clock, while the rear cylinder is at 1 o'clock?
3. When the magneto slip ring was overhauled, the bill was marked as "Slip ring (right hand". What is the significance of "right hand" - can't get hold of my mag man to ask him.
4. The dwell on the points opening to closing seems to be from 50 degrees before TDC to 90 degrees after TDC. That seems an awfully long opening to me, but I have no experience on type.
Thanks once again for all your suggestions.
Patrick

eddie · « **Reply #29 on:** 08 Jan 2016 at 16:02 »

Right, Patrick,
Item !. Providing you have installed the cam followers the right way up, both cylinders will be timed the same (on the valves). With the followers set up correctly, the faces should be vertical.
Item 2. I suspect that your magneto (or parts of it) may have come from a 'V' twin engine. At this stage, you should arm yourself with a felt tip marker pen. Then turn the engine until the points just start to open for the front cylinder, then mark the flywheel with the felt tip to give a reference point against something like the top of the primary chaincase. Carry on turning the engine forward (anti clockwise on the flywheel) until the points just start to open for the back cylinder. The flywheel mark should line up with the top of the chaincase again. If it is a long way out, then your mag is probably fitted with a camring for a V twin. If this is the case, take the mag to a reputable reconditioner and tell him that it is to be fitted to a flat twin. (If your mag was taken to a reconditioner with the request to just refurbish it, and it was from a V twin, then the reconditioner would have refurbished it as a V twin mag!).
Item 3. Left hand or Right hand just refers to the rotation of the mag - i.e. clockwise or anti clockwise.
Item 4. 50 degrees before TDC to 90 degrees after TDC is 140 degrees of crankshaft movement - this equates to 70 degrees of magneto rotation - and that sounds about right to me.

If your mag is suspect, don't try putting it right yourself by substituting other parts - there are a lot of variables depending on which engine the mag was intended to fit. Everything on the armature (along with the camring) has to match in order that the spark occurs at (or close to) the point of maximum flux in order to obtain a strong reliable spark.

Regards,
Eddie.

patrickhowell · « **Reply #30 on:** 09 Jan 2016 at 10:26 »

Eddie
1. I suppose it would be possible to instal the inlet cam follower 180 degrees round. As installed, the longer "toe" is pointing upwards. I can't see how it would be possible to get it wrong with the exhaust cam follower, owing to the disposition of the valve lifter mechanism.
2. The overwhelming argument against it being the wrong magneto cam ring is the fact that before the armature broke down, the engine started perfectly first kick, and ran well.
3. If you are viewing the mag from the flywheel end, and right hand= anticlock movement, then the slip ring would seem to be correct.
I have to admit that the armature was initially the only part sent away for overhaul, together with replacement of the broken slip ring, but I did return the mag to the repairer for remagnetisation, and replacement of the carbon brushes and brush holders, and HT leads. The repairer did comment that one of the holders was foreign, and replaced it with a BTH part.
Thanks, as ever,
Patrick

patrickhowell · « **Reply #31 on:** 09 Jan 2016 at 14:20 »

Eddie
Thanks for your personal message, I'm not sure how to respond to it except through this forum. Let me say at the outset that I am really grateful for the input chaps like you give; even after sixty years around bikes, my ignorance is greater than the sum of my knowledge, and I welcome any experience anyone can offer.
I have followed up the very useful tip on checking the valve timing, and everything checks out OK, which takes me back to the ignition timing. I agree with your thoughts about the one o'clock and nine o'clock positions (assuming my observations are correct), but can't really see how the mag would have worked before, or what could be done about it now. Clearly, the 'obvious ' is escaping me. Where are you in Hampshire?
Patrick

DSIM · « **Reply #32 on:** 10 Jan 2016 at 00:15 »

just a note to mention that you can get flexible silicon sealant that will take 1200C at about £10 a tube for a standard sealant gun BLACK 1200°C Fireproof Silicone Sealant Envirograf ... - eBay is just one,

graeme · « **Reply #33 on:** 10 Jan 2016 at 09:41 »

Patrick,
Is there the possibility that your mag repairer has mixed up cam rings, and fitted one from another magneto to yours? It does sound like a V twin cam ring from your description of the symptoms.
Regards, Graeme

patrickhowell · « **Reply #34 on:** 13 Jan 2016 at 08:01 »

Graeme
Thanks, I thought the same, but when I took the mag off, I found it was in fact a 180 degree cam ring. With the mag in place, the flywheel obscures part of the opening sequence, so I got it wrong. BTW, my mag man says that V-twin BTH mag cam rings are as rare as hens' teeth. Unfortunately I am no further forward.
Patrick

patrickhowell · « **Reply #35 on:** 20 Jan 2016 at 15:00 »

Today's daft suggestion. Is it possible to accidentally transpose the inlet and exhaust pinions/ cams, so that the inlet cam goes in the exhaust socket, and vice versa? If so, are they identical or not, and if not, would that no upset the valve timing?