I'm a tinkerer of everything but an expert at nothing. After 15yrs of this , I think it might be a very old distributor but not sure. Original 440, 150K which originally had holley which ran bad all the time. Car was abused before I got it. 15yrs ago while restoring car, I bought a rebuilt 1972 TQ to 440 spec which has been an excellent carb during normal driving in all weather conditions, easy starting, no stalling, no constant adjusting and great gas mileage. The only problem is when I floor it (which is seldom). Most of the time, it bogs out to the point where it sounds like I turned off the car, then I let go of accelerator and stomp on it again, then it usually takes off, (sometimes I have to do that twice) Yes, I've played around with the secondary spring screw to the point where the secondaries open very slowly (so no power), checked vacuum dashpot, metering rods, mix screws, etc and I still get the bog and pop. Sometimes it bogs a little, then backfires thru the carb, then takes off. One time it exploded in the mufflers and now car sounds pretty cool. However, car accelerates better after I stomp on it first 1-2 times. Usually bog or sputtering is less to none for whole day until next time I take it out for a ride. I changed to a Petronix in original distributor which may have some play on shaft, not sure how to check. Runs smoother but didn't help bog and pop. Installed crane adjustable vacuum advance but how do I adjust to stop bog and pop? Anyone know if I used correct vacuum nipple on the carb for vacuum advance? (see pic) Will a new distributor fix this? Thanks for your help? Timing is a little advanced since it seems to start and run the best that way. Anyone know what I'm doing wrong?