Have you read what Smokey Yunick found out about cam movement in a running
engine?
Very interesting. Because of the variable forces at work on the cam (pressure on
different sides of the cam lobes from the rockers), it does NOT have the nice
smooth forward motion that we tend to visualize. The cam actually shifts
BACKWARD
occasionally as the forces change. If you don't believe me (and Smokey), just
put a
wrench on the cam next time you have the head off the car, and feel the forces
as
you try to turn it slowly. Add a bunch of slop in the chain and you can see why
cars start to run poorly as they wear out.
Thomas Walter wrote:
> I am still down right baffled by that lower chain guide. I think mentioned
> asking a mechanical engineering friend to make a computer model of the chains
> and jackshaft and camshaft. The lower chain guide can ONLY function as a
> step of high rpms being let off, and the chain 'back slapping' that guide.
> Odd thing is with time, and VERY WORN OUT chains, it will break that lower
> guide off. Basically it serves no purpose other than to fail with worn out
> chains! Odd. No never got the full model made, but maybe I'll get LEARN
> how to use the full engineering package of Matlab & MatrixX someday to play
> with this some more. Dynamic model is pretty interesting with a camshaft.
> Fun thing with my job, as I get paid to go off an think about these things.
>;-)
--
Gordon Glasgow
Renton, WA
http://www.gordon-glasgow.org
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