compression ratio vs octane

You can also slow down your mechanical advance so it doesnt come full in until 3000. If it has an issue, it will be at low rpm in high gear when the rpms are down and the load is high. Once it starts, it's hard to get pinging to stop. So the trick is to keep the initial ping from happening. Solve the issue at 2300 and you'll be fine at 2400 and up. (assuming there is a problem... :) )