Formula350

iTrader: (3)

Bored and dicking around with Desktop Dyno (to see how much compression goes up from stock) and trying to get gasket specs. I thought the factory Aluminum head gasket was 4.125 @ .044 compression thickness. But apparently it's .050? Which if so, throws the CR to 10.39 from 10.41 (which is stock I though). Anyways, that's small potatoes compared to what I'm coming up with for the B-Body gasket! GM P# 12553160 is coming out to be .028 o_0 I thought it was a typo, but even GMPartsDirect says for LT1s :\ I can't even get you a GMP# for the .039 though.

And I only ask in confusion due to a discussion a while back on approximate CR gain by switching to the .039 gasket, gaining you around .30 CR. Which, adding in that thickness, nets (going from 10.41) .29 CR! Now, if we use the .028 gasket, that nets you .61 CR! Which brings us just over 11:1! Pretty much making the motor a "has to run" 92oc instead of a "should run"... And Desktop Dyno predicts a gain of 7hp and tq from that (knock me using it all you want, but I've plugged in all the numbers and oddly enough, have a 275hp/325tq simulated engine! ).

OR are all my numbers wrong and it's .050 before crush and .039 after crush for Aluminum, and .039 before and .028 after on Iron? If that's the case, then the previous talked about .30 CR gain is still right, and this thread still served a purpose of clearing up my confusion

96capricemgr

iTrader: (1)

I believe most of the LT1 gaskets are a 1.110 bore.
These should all be crushed dimensions and subject to manufacturing variation.
Victor Rienz/Mr. Gasket being .026
Cometic offers a .027/4.040 (other sizes too but this would be the one for more compression)
Stock b-body is .029
Felpro is the .039
f-body is .049
LT4 I have seen enough different specs on to not be sure, but have seen a thick as .054 claimed
I have not looked up the bore on all of them but have on a couple and found 4.110.

Formula350

iTrader: (3)

Thank you