Timing Question

what is the initial timing set at (timing at idle)? What is your idle rpm set at? How much mechanical advance do you have it set at and at what RPM, are you running vacuum advance or is this blocked off? The only reason why it would be pinging under load (if the initial and mechanical advance are setup correctly) is if you have too much vacuum advance coming in. With the rpm you mention you shouldn't have reached full mechanical advance yet. probably should be in around 2500 rpm. Do you find it still pings if you block off the vacuum advance canister? Does it ping if you put your foot down at low rpm (no vacuum)?