[miket]

Originally posted by veltex
OK, changed plugs to AC45 gapped at 45, still does it, gapped at 35, still does it, tried two other stes of plugs, it aint the plugs. Dwaite, dist came with springs and specs(I have the middle set in, also adjustable vac advance, dist advances properly I think it runs it up about 18, could get more with the lighter set, but that may worsen the problem. Starving for fuel at cruise could be it, when you kick it down it runs great without pinging (at least that I can hear, its loud), and parked revs cant make it ping, it has to be under a load. I have tried a couple brands of gas. How do I make the carb(edelbrock thunderer) fatter in the middle? Am I missing something, will octane boost give me an idea if its gas related? help

Based on the changes you made the only things I can think of are the advance of the new distributor. Maybe you have a failing fuel pump and with the new advance curve (or changes from the old) you might be running lean at a point in which the dist is advancing timing...how about an open vac line? just thinking out loud.