I can't decide which head gasket combo would be better for my application, so all educated opinions are welcome...

First a little background on the rest of the engine: 350ci LT1. It's a four-bolt main, standard bore with a stock crank, 0 decked block. Scat 4340 I beam rods with 7/16th bolts, Probe forged flattop pistons. (-4cc valve reliefs) The heads are ported stock castings (270+ @ .600) and the combustion chambers ended up at 55cc. The cam is undecided, but I'll probably contact Bret Bauer for a custom grind. I'm thinking something similar the gm847 as a reference... I'm looking to make 400+rwhp and don't mind spinning the motor over the 6500 range. As for the rest of the package, I have long tubes, EWP, 58mm TB, etc, etc, etc.

Now for the question: I had originally planned to run Fel-pro 1074's, but started thinking maybe I should buy a set of Cometic head gaskets since I plan to spray this motor every now and then. I had calculated my Static CR at 11.49:1 with the Fel-pros (.039 compressed, 4.125 bore) I'm wondering if using the .036 compressed, 4.040 bore cometic gaskets would be a wise choice? Those would put me at 11.7 : 1 which I don't think is any worse than 11.49, but would that .036 quench be ok for a motor that will have to live on 91 or 93 octane most of the time? Or should I just stick with the 1074s?

 

My opinion, yes. Your 036 quench is good. The fact that it has to live on the pump gas you can get makes it even more important that the quench be nice and tight.

A lot of people will say that an 035 quench is the tightest you should go. I personally like an 030, but I'm funny about blocks.

 

That's perfect man. The more compression you have the more the larger cams with the late intake valve closing points will like it, especially if you have gear and RPM with your M6.

Bret

 

Thanks for the responses guys Ok so your saying the .036 is the way to go then? I guess I'll sell my 1074s and order the cometics.


btw, Bret I'll be contacting you for a cam soon

 

I'm switching over my street motor that's going into my GTO to run cometics as well. As long as you have a smooth enough surface finish you can run them with no problems, and they are bad *** because they are reuseable.

Bret

 

I was very impressed with them when we used them on a buddie's LQ9 based 402 for his '00 ram air TA recently, thats why I started looking to see what they had available for my LT1 Looks to me like they are the way to go for sure

 

I just used them on a LT1 build that is going on the dyno here soon, they are a killer head gasket.

Bret