Shane's Method Question.
03-12-2014, 05:23 AM
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Shane's Method Question. Shane suggests using the EO/IC method to ensure the lifter is on the base circle of the cam when taking measurements and torquing down rocker arms. Why not just turn the engine over until the piston is at top of its firing stroke? At TDC on the firing stroke surely both lifters for that particular cylinder will be on the base circle of the cam. Is there something wrong with my thinking? If so what?
From Shane's method.
"The TDC method is NOT always accurate. Try the EO/IC method to check pushrod length. "
AND
"If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve."
From Shane's method.
"The TDC method is NOT always accurate. Try the EO/IC method to check pushrod length. "
AND
"If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve."
Last edited by nzgreenfox; 03-12-2014 at 05:37 AM.
03-12-2014, 05:52 AM
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Your dead on the money. As long as the piston is at tdc for it's combustion stroke then both intake and exhaust lifters will be on the base circle of the cam. The intake valve has been closed well by this point (or else you'd be bleeding pressure on the compression stroke), and the exhaust valve is well closed (or else you'd be bleeding you air/fuel charge and compression.).
I think Shane is trying to get at, if you don't know if the piston is at TDC for the combustion stroke, or exhaust stroke then the readings can be off as only the combustion stroke will have both intake and exhaust on the base circle of the cam.
The exhaust stroke can have both intake and exhaust slightly open due to overlap.
I think Shane is trying to get at, if you don't know if the piston is at TDC for the combustion stroke, or exhaust stroke then the readings can be off as only the combustion stroke will have both intake and exhaust on the base circle of the cam.
The exhaust stroke can have both intake and exhaust slightly open due to overlap.
03-13-2014, 10:56 AM
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I've always done it by rotating the engine and waiting for the intake valve to close, then rotating it a few degrees more and tightening down both valves, that should give the most time for both vales to be on the base circle. I prefer to go from one cylinder to the next instead of jumping around. I have a ratcheting breaker bar and take the spark plugs out so it's not too difficult. Using the firing order to tighten them is less work since you only rotate the engine one revolution, but I never accurately marked my balancer.
