1970 GMC Truck carb.

Carburetors don't pop. Worn, fouled, or broken parts can cause a backfire "through" the carb, but it's not the carb. Ignition timing, point dwell, if you have the old style distributor, a partially fouled spark plug, a weak or loose plug wire, and maybe even a camshaft with one or more worn lobes. You have lots of things to check, but you will find the problem if you are patient and take your time. Good luck. Mickey-d