I don't have vacuum advance...it's an MSD distributor & 6AL Module. I've actually spoken to hpmike (a regular contributor on this site & guru on 6-bbl's..he's set up several F.A.S.T. 6-bbl cars) and have arranged for him to check the carbs & timing. His shop is only a few miles away. He test drove the car and noticed pinging under load. Also, the temp gauge has always run hotter (1,500 miles now), so I suspect I'm running lean and/or my timing is too advanced. Thanks for your interest and help...I'll keep you informed of the outcome.