Don't know if you are refering to me or not Demon. My car has a 67 440 hi po that was overhauled close to stock specs by Jasper last year. Compression ratio is probably around 9.5:1 according to the info Jasper provided. I run pump unleaded premium with no ping or other issues. It did detonate on WOT before the overhaul if that means anything...it doesn't now. Far as I know, the cam is the usual Mopar BB hi po set up as included in the 375 horse 440 motors.