Still trying to work out my pump gas tune. to this point the best pull the car has been able to make with out detonating is 575 hp that was with close to 17 psi with only 8 degrees of timing. i have a single 76 car with a .20 over bore. for some reason it will not hold any timing. we thought the first time it was a bad gas issue. I drained the tank out and put in new gas form the place i have always gone. and had the same result. the car sits right now once again with 8 degrees of timing and 15#'s. any idea what could be causing it to detonate with as little as 11-12 degrees. I know it should be able to get over 650 hp on pump gas at 16-17 psi and 14 degrees. Looking for ideas? any suggestions help. thanks