which cometic head gasket and why?
 

I'm getting ready to order head gaskets and I'm trying to figure out which cometics to use with my set up. There seem to be many options cometic offers for an LS1. Which gasket would yield the best performance gains?

This is what i have:

stock bottom ls1
comp 228/230 .571/.573 112lsa (intake 71* abdc)
ported unmilled 799 heads with stock valves

cometic gaskets:
part# / compressed thickness

C5475-040 (.040")
C5475-036 (.036")
C5475-030 (.030")
C5475-027 (.027")

any advise?

the only thing i know about the cometics is that they are not as forgiving as the oem MLS gaskets about the sealing surface. from what i have been told both the block and heads have to be perfect.

I would not go thinner than .040" due to reduced quench clearances and due to the thinner you go the harder they are to seal. Personally, I like the GM MLS gaskets.

I had the same question. Actually, I registered specifically to say to ask this question..

So, any advise will be so much appreciated

.040 or .045 for me. Also depends on how much the piston sticks out of the hole.

I would use a 3.910 or so head gasket to keep the quench higher also.

With stock pistons id use the .040" gaskets, i'm using a .027" cometics gaskets but iv also got -8cc dish pistons, if had a smaller dish piston would've used a .040" myself.

yeah i used the .045,but if i could have done it again i would have went with the .040.. I also have the same cam as you OP

I'd also use the .040". On average your piston sits around .005" up out of the hole so that would give you a .035 quench..035-.030 is optimum, when you get tighter there are gains, but as the metal stretches and expands it leaves less room for error.

are the cometics as good as the gm mls gaskets?

We keep them in stock. Shoot me a PM or give us a call and we will get you fixed up!

i'm gonna try the FP permatourque gasket, it's just a stock LQ9 though..