Everybody here talks about using 93 octane gas. Unfortunately, I live in California, and all we can get (without buying racing gas) is 91 octane MTBE fuel. I am putting a set of heads that are milled 0.030" on an otherwise stock bottom end. The head porter recommended going with the Impala 0.029" compressed thickness head gasket. That would make for 11.8:1 compression. Will that survive with 91 octane pump gas?

I will be using a Comp XE 230/236-112 cam. I know that you can run a higher static compression ratio with a bigger cam, but will this work?

If not, I can use either the stock gasket (0.049”) or the Felpro (0.039”)

 

Everything is a balance ( with in reason ) The more timing you run (at the same compression) the higher octaine you will need. The lower oct that you run ( same compression ) the lower your timing will need to be to prevent knock. 11.8 seems high to run on 91 even with pulling out a bunch of timing but I don't know for sure. -- Octain booster