Whenever I go full throttle the car sputters bad and the exhaust pops. This always happens when I hit it from lower speeds, and sometimes when I hit it from around 50/60. I just recently had my float and idle set. The carb is a holley 600 4bbl. Motor is a 289 with a c4 tranny.
Mine was doing that and after tuning and retuning the carb, installing Pertronix II, triple checking the timing and firing order, and putting higher and higher octane gas in it, I finally found the culprit to be one poor spark plug lead that had been intermitantly working. It eventually provided zero spark for me on one occassion when I was rechecking the plugs so I switched it with another wire and the problem followed the wire to the other cylinder. Threw a new set of wires on and presto! Car runs like a top.
Could be too much fuel from accel pump. You could reduce the accel squirter nozzle size or change the pump cam to one that has a smaller profile (smaller cc shot) or move the attachment screw to the opposite position that it is in now.