T67, Another thing to consider is the timing curve. Once the engine goes into ping or detonation, it won't "get out" until you let off. However minor changes in the timing curve, meaning the rpm points at which the advance comes in, can stave off the first signs of it and thereby stop it altogether. Also, ping and detonation come from liquid fuel, not vapor. So anything you can do to help make the mixture more thorough the better. I've found by slowing the advance to bring it all in by say 3000 rather than 2400, and using the power valve ratings rather than the acc pump or jetting to richen things I can tune ping away without any loss of response or power. Not all engines need the standard "34-36° all in by 2400" deal. Many open chamber combos relly don't.