Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Can you give me some specs on the engine, stock, mild rebuild, camshaft etc?
You may have collapsed lifters or worn cam lobes.
Can you check all the valves close fully in sequence?
Can you do a compression test after, if all valves appear to be the same height (valve stem tip)?
Sounds like the popping would be an exhaust valve not opening, it has to go somewhere, hence the popping back out the carburettor.