[ChevLoRay]

I had an Edelbrock 1405, that ran rich...so rich, in fact, that it would gas-foul the #2 spark plug. I don't know why it was that one in particular, but it was. I knew it was about to happen when the pipe on the right side (true duals-no crossover/balance tube) started to pop like it was backfiring.

Now that I have a model 1901 Edelbrock (Q-Jet), I have had no more gas-fouled plugs and it won't pop at all, even if I'd like to hear it.

So, it may be that your carb is jetted on the rich side, for your engine's needs, and that is the source of the fuel that is popping.

Usually, a vacuum leak will cause the engine to have a "miss", rather than a pop, in my experience. Sometimes, the easiest and cleanest way to tell if you have one, is to simply remove the air cleaner ass'y, and use your hands to smother the engine at the air horn on the carb. If you don't have a leak, it will die. If there is a leak, you can vary the amount of smothering you do, and it will smooth out. If you can completely cover the carb without it dying, you gotta hella leak.