Ok,
So, to follow up on Gordon's response to the question of why there is a
gap at all. And, the idea of running the valves tight ...
You get both better performance "potential" and it's associated elevated
risk when running on the tight side of the tolerances. Too tight, and the
valve may one day fail to close properly or completely. If that happens
the valve and/or it's seat burns and fails to effectively seal. But, at the
ragged edge, you maximize flow by running the clearances on the tight
side because the valves open farther for a marginally longer duration.
So, why not just cam the motor. Well, if racing where the cam's lift and
duration are spec'd there is some power hiding in valve adjustment
tolerances.
If you want to approach this ragged edge, I'd suggest adjusting your
valves hot rather than cold. Understand that it is hard to get to the
valves when they are hot, and they cool quickly. You might end up
getting two adjusted before needing to get the valve train back up to
operating temperature so you can continue.
If you aren't racing, it is much safer and easier on the motor to just buy
the cam you want.
Milton
On 30 Jan 2003, at 21:56, Gordon Glasgow wrote:
> Part of it is to allow for expansion of the parts when hot. That will close
> down the clearances.
>
> A couple of other reasons for not running zero lash would be excessive wear
> from the constant contact between cam and follower (or rocker), and the fact
> that as the valve sinks further into the valve seat with wear, the valve
> wouldn't completely close.
>
> Gordon Glasgow
milton <milton3@pobox.com>
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