I used to be able to get 93 here in central OK. No more. Best I can do is non ethanol 91. The engine currently in my 69 Z is built to 70 LT-1 specs with a thin head gasket and true compression is around 11.5:1. No telling what it is on your car. Most likely north of 11:1.
Set your timing at 36 total, and try a tank of 93 if you can get it. If not, try the highest octane pump gas available. If it doesn't ping, you're good.
If it does, then run some of that 100LL you have access to. I am lucky to have access to the local airport, so it is easy for me to get. That is what I run in my Z currently. It pings like crazy on 91. Yes, I COULD back the timing off enough to stop it from pinging, but I prefer to used good gas and enjoy the full benefit of the higher compression engine. I also use it in my lawn and garden stuff. It has a much longer shelf life than the stuff at the pump.
Gas is different in different parts of the country. I notice every time I venture down to Texas, once I get far enough south, there is 92 and sometimes 93 at the pump. So, when some one tells you they can run pump gas in their performance car, they MAY just be using better gas. New cars with computer controls are a whole different discussion.
