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Warped heads (was: Good machine shop...)

To: dana nojima <noji-1@pacbell.net>
Subject: Warped heads (was: Good machine shop...)
From: "John F Sandhoff" <sandhoff@csus.edu>
Date: Fri, 19 Oct 2001 11:25:50 -0700
It was asked:
> What doesn't make sense to me is that if a head is warped and you shave 
> the bottom, wouldn't the cam alingment and the top be warped also?

YES.

This has been discussed as the reason for cams mysteriously snapping
in half. BOTH sides of the U20 head should always be checked for
flatness, and during assembly the cam should be checked to be sure it
turns smoothly.

And after shaving, tower shims should be used to return the cam to the
engineered height, to keep the chain properly tensioned and the valve
timing correct. Of course, then the wipe pattern on the rockers should
be checked to be sure the valve geometry hasn't shifted too far....


-- John
     John F Sandhoff   sandhoff@csus.edu   Sacramento, CA

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