Engine backfires thru carburetor only on initial acceleration off idle. Will run all day beautifully at 2k -4k, idles perfectly just spit and backfires every time I give it gas clears and runs.. out of water. In the water that initial “cough” stalls the engine every time. This is a brand new reman 3.0 gm on a 1991 Caravelle I’ve cleaned and rebuilt the 2 barrel holly carburetor. new plugs wires distributor rotor. Timing is set dead on with shunt, advances as it should about 10 degrees at idle. (Set base at 0 per manufacturer) I’m stumped. Any advice would be awesome.
