What's the best head gasket material for aluminum heads? Composition, copper, steel wire ring?
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After running Mercruiser heads gaskets on my 540 for 7 seasons, My head builder suggested Cometics, less wear and tear on the head it's self.
My engine builder said cometics are great for boosted applications, and overkill for NA motors. ????
Another Hot Boat refugee
Overkill is an interesting term. They are a tad on the expensive side, when a lesser priced deal will seal just fine. But when I want good seal, I like the overkill idea.
With the MLS style gaskets around, I really don't know why anyone would "O ring" a block and head any more. Keep them both flat and run a good gasket. If you are going to be throwing lots of boost at it, the self sealing SCE gaskets work great too.
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When I built my 565ci all aluminum blown alcohol engine I tried cometics and they wouldn't seal. However, I used 1/2" head studs with a 4.600 bore that left very little room between the stud and the bore for sealing. I used SCE Titan gaskets and it did the trick.
felpro 1017 if you're not gonna run alot of boost or nitrous, they're composite gaskets with a ss ring, i've ran 12lbs of boost and up to 450hp of nitrous on em. most alum heads have 4.5 chambers , so whatever gasket you decide, make sure to check it against the head as well.
Dare to be different, if it turns out great you can claim you planned it that way.
What gasket was the block honed with originally?
The reason I ask is that if it was honed with a standard type composition gasket, switching to an MLS style will distort the bore allot different. (MLS type being allot less) We have seen as much as .002 on a GM racing small block. This difference will vary depending on block used (cylinder wall and deck thickness) and stud/bolt location and hole type (blind hole vs. through ect.).