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Old 01-22-2002, 09:29 PM
Kebowers Kebowers is offline
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Join Date: Jul 2000
Posts: 638
where did MPG go? look to the head!

What did you do to the head? Face the gasket surface? If so, you removed some metal that is equivalent to more than 100,000 miles of timing chain stretch/wear, and the cam timing is probably several degrees late- unless you carefully checked it and put in the offset camshaft key(s).

A real common oversight with aluminum head overhead cam engines is resurfacing just the head gasket surface without also resurfacing the top side at the same time to ensure the two sides remain perfectly parallel. This required completely stripping the head (removing all the guides, cam towers, etc.

The heads are very flexible, and often seem 'bowed', or even twisted when laying there in the open, but straighten out when torqued down. Unless the head WAS perfectly true and a uniform amount of metal was removed and the top and bottom sides maintained parallel, you now have cam journals that are no longer perfectly aligned. You will have to add shims (see the parts counter) under each bearing tower to get them back in place. A tight cam can consume a surprising amount of power to turn. It should be possible to turn it by hand when the head is torqued down (without the rockers or chain installed of course.)
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