ok i have sbc 383 with a edelbrock 750, summit 1105 cam, world products sportsman 2 heads, pertronics hei, 2.73 gears and a th350 trans in my 70 nova. I have a bad part/mid throttle stumble and the engine pops thru the carb. The car pulls like crazy thru 6000rpm at WOT. At mid range rpms and part throttle she stumbles,loads up and pops. The carb is still at factory settings except for the pump linkage, which I have set for the longest stroke. I have moved the timing from 8 to 12 BTDC and back again. any help would be great.

thanks