Valve Timing

[mike.dowling]

Hi
I have a model 16 350 1960 and have been having a few problems lately and although I thought it ran fairly well it was never brilliant, and until i rode another bike I realised mine was bad. I needed to take the head off to deal with an oil leak from the pushrod tubes so deceided to look at the valve timing at the same time this is where the trouble starts.
1. Both my cams are marked 2 and 3
2 The exhaust cam is 6 teeth out from the markings and the inlet 7 out.
My book says use mark 1 exhaust cam all touring models
use mark 3 for inlet cam 350 touring models.
Maybe i'm missing something but I cannot believe it would run so far out but it ran and started easialy so i'm a bit confused.
Any suggestion ?
Regards
Mike d.

[laxy]

Hi Mike, with three dot cams turn the engine so that the dot on the timing pinion faces the inlet cam {10 0clock position} then fit the camshaft so that the lowest of the two dots line up with the single dot on the timing pinion. Rotate the engine forward so that the timing pinion dot is facing the ex. cam.{two o clock position}Offer up the exhaust cam with the top pointing to approximately ten oclock and you should find a single dot close to the dot on the timing pinionThis is the dot to use.This method applies to the 350cc different rules apply for the 500.Also using this method it doesent matter if the cams in your engine are not correct for the year.
this info is taken from a magazine article by Ken De-Groome who is a specialist in AJS/MATCHLESS singles and advertises in the back of the jampot best of luck,keith

[mike.dowling]

Hi
I've tried that method of lining up the cams when I do it that way when I turn the engine over I never get both valves closed at TDC on either stroke.
There has to be something wrong with the marking or something, on the lobe on the cam is stamped an "H" does that have any significane I dont know.
Regards
Mike d.

[Stan Palmer]

Does your instruction book give the valve timing in degrees for start of lift and end of lift ?
If so it is relatively simple to set up a timing disc and DTI to check what is happening, shifting round a tooth at a time (18 degrees) to find best compromise. You have to make allowance for the quietening ramps (16 thou), so allowing the cam to lift 16 thou before deeming actual start of lift. But don't expect to get it perfectly right according to the book figures, my standard set-up gave errors of 7 degrees plus, but in practice a small error doesn't seem to matter that much.
The long stroke timing is inlet opens 32 BTDC, closes 63 ABDC. Exhaust opens 65 BBDC, closes 30 ATDC (B=before, A = after, TDC = bottom dead centre, BDC = bottom dead centre). I am sure it will be different for a shortstroke but even those figures might throw some light on what the markings mean.

StanEdited by - Stan Palmer on 11 Aug 2010 07:21:23 AM

[mike.dowling]

Hi
You must all think I'm a total plo***r. I've solved the problem and it all looks good now.
The inlet cam had a very faint number 1 mark about 120 Degs away from the 2 and 3 mark, I couldnt see a mark on the exhaust cam only a blob of red paint it was timed to before. I counted how far round the No1 on the inlet cam was, counted round on the exhaust cam the same ammount and then realised there was a dot on the inside of the cam. fitted it to that mark and it all looks good.
Tommorrow will tell the tale as to if its any better.
Sorry for the trouble i'll get my magnifying glass out sooner next time.
Regards
Mike d.

[wilko]

That seems quite radical timing Stan, sure that isn't for SH's.

[Stan Palmer]

You're right Wilko, I opened the book yesterday to get the figures correct, wrong page, too much hurry, those are scrambles figures. I will modify the original post to avoid confusion.

Stan