I had the same problem.........long story short, when i put on the balancer and installed the timing tape i was off, and had the same experience you are having...right now i have the hei unplugged all the time. no vacuum advance. Use a vacuum guage to set and tune your carb.....i had the popping, might be too lean and too advanced in the timing. sometimes it takesa few cracks at ti to get the engine to run where its happy......takes time. thats the fun part about hotrodding. I have also found that with my holley it has a very small ideal setting...slight movement eithere in or out on the mixtures wreaks havoc....be patient