There are shops that specialize in straightening aluminum cylinder heads.
They have fixtures and ovens to control the process. They can get the
straightness to within .010" most of the time. It may be good to replace
the guides and seats after the heating process. It is usually necessary to
skim both the top and bottom of U-20 heads. Straightening also tends to
retain the combustion chamber volumes more equally.
Stan
===============
At 01:20 PM 10/19/01 -0400, you wrote:
>That is correct. If a head is warped badly you'd need to mill the top of
>the head or align bore the cam towers. That's why some folks straighten
>them first. The procedure the mechanic described to you is how it's done.
>While it sounds simple it takes some experience as the head must be heated
>evenly to the proper temp and cooled evenly as well. I'll try most anything
>myself but that is a service I'd pay someone for.
>
>Brian '69 2000
>Tampa, FL
>http://web.tampabay.rr.com/oilleak/
>
>-----Original Message-----
>
>Years ago (1989) I remember talking with a mechanic at the loacal Nissan
>dealership. He had mentioned that he had been able to straighten heads
>by clamping them on a bench with spacers then heating them to bring them
>back into alignment. This sounds very shade tree, but fortunately I've
>never had to worry about this particular problem.
>
>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? This
>would me that you would need new bearings/and have the cam alined bored?
>
>Dana "now w/real job w/o car sig" Nojima
>
>datsunmike wrote:
>
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