Quote:
Originally Posted by yieldsign2
I have an 89 3.9L RRC, what should the stock headgasket material be? The one I removed is all metal (steel?), just wondering if it is stock that way or if there is fiber/fabric type as well.
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There is. Pre-4.0/4.6 engines use metal head gaskets and 4.0/4.6 use composite fiber gaskets. The later gaskets are much better.
However, they are also thicker. To keep up the engine compression, LR skimmed the 4.0/4.6 heads (which also reduced the size of the combustion chamber). If you use these gaskets with your heads, your engine compression will drop and you can expect a power drop of 15-20bhp (8-11%) Of course if that doesn't bother you, your engine will last longer and be less likely to ever blow a head gasket again.
BTW, a cheap move for more power for a 4.0/4.6 is to switch to the earlier metal head gaskets. The compression rises to 10.1:1 and there is another 20+bhp.
James
