I have a 400 small block that is +.040, with a comp XE262 cam (218 I/224 E; .462 I/.469E). The heads need some work, and I'm considering replacement heads. I would like to use the new Vortec's, but am afraid I'll end up with too much compression. I built the motor about 3 years ago using pistons with a small (12.5 cc) dish, shooting for 9:1 with 76 cc heads.

I've got a lot of deck (.039") and with a .051 head gasket my calculation shows I should end up with about 9.7:1 compression. I run the car fairly hard and don't want to end up with compression that is too high. In your opinion, at 9.7:1 am I asking for trouble?

Well, it depends on what you consider pump gas. If you are depending on 93 on getting you by with iron heads and an XE262, then you have a problem with cylinder pressure.

Even though I like the L31 heads personally for the buck, you might consider an aluminum head for your 400. No problem with those and will likely produce as much flow as the Vortecs if picked correctly. More $$ tho.



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Steve Jack - ConceptOne Pulleys and Brackets / Engineering & Marketing Technologies

At TDC , is the highest surface of your piston .039" in the hole or abve the deck of the block? Do you have a standard stroke crank or a stroked unit? What specs is your ig. system? Are you planning on using iron or aluminum heads?
If your engine is not set up with a small enough "squish" area, you may wind up with a chronic case of detonation...Ideally, the distance (@TDC)from the highest point of your piston to the head surface sould be .040". This is of course, with the appropriate thickness head gasket in place and smashed down to specs with, at the very least, oil on the threads of new head bolts and tightened to the correct values...
Looking forward to your info...