Motor is popping back through the carb... Help!

So I have recently changed out my cam, timing chain and gears, lifters, pushrods, oil pump, pickup tube, oil pump shaft drive gear, spark plugs, cylinder heads. When I changed out everything I made sure that both timing marks lined up dot to dot, car started right up at initial fire up and ran well. Took it out tonight and on the way home from a short run (about 5 miles) the car started popping back through the exhaust and carb. Throttle response is not good. Got the car home and popped hood and checked for any signs of spark that may be jumping. All wires look good, no sparks jumping, cap looks good. wires and cap are less than 1 yr old. no visible intake leaks. tried to adjust distributor, does not matter where I set it at, it still pops back. Wondering what the issue may be. Carb is an edelbrock 600 and is fairly new.