SOHC.co.uk Forums > Anorak's Corner
Carburettors with more depth of discussion
K2-K6:
Ooooh, that wouldn't help :o if there's error there John.
Definitely best to check and eliminate a fundamental like that.
McCabe-Thiele (Ted):
I suspect if you were a tooth out on the Cam it would be very obvious.
You may already know there is a realtively easy way to check valve timing iirc Bryan posted on the subject on my 400 project.
Bryan has explained it reproduced below - with plugs out.
Get all the tappet covers off, as the mark approaches 1-4 TDC or T watch the valves on number 1 and number 4 cylinders, one of them will have both valves going down/up, the other will have them both up, the one with both up is the one to do. If you grab a tappet adjuster you can rattle the one on compression stroke, if it's number 1 (and it's a 50/50 chance of it being that) then after doing the tappets turn the crank (clockwise, always clockwise) then as 2-3 T mark comes up you do number 2 cylinder, turn again to 1-4 and do number 4 and lastly turn again to 2-3 T and do number 3 cylinder. The firing order is 1-2-4-3.
K2-K6:
They'll "run" and without contact I think, with 1 to 2 teeth out in my understanding.
Not that you'd want to do that, just that it could be done without catastrophic contact of the wrong components.
Quite possible and needing a check definitely to avoid the resulting running shift that's in place if that were the cause.
Additionally, if tbe cam were to be run advanced the effect should be to move the torque higher at the expense of crap idle symptoms ;D so, a possible cause that needs to be eliminated.
Classic fault finding ..... ask what was changed between working and not. Carb rubbers to head were, but have been checked for leaks. Carburettor setup, no. Is there something else that could plausibly have changed that can affect it, yes. How do we now check and verify that ?
Johnwebley:
Problem solved
The cam was one tooth advanced
Silly me
Running sweetly now, but it has some new carb rubbers
Lessons learnt
A simple error can result in a red herring looking for a fault that does not exist
Sent from my SM-A546E using Tapatalk
Johnny4428:
Glad you have sorted John!
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