'72 BB consistent muffler explosion
I have a ’72 402 BB engine. The engine was totally rebuilt 5 years ago and I installed new rod bearings, rings, mild performance cam with timing gears, lifters, and ground the valves and seats. When the engine was fired up it ran like a fresh motor, not issues. It has a stock points ignition and a 4 barrel Qjet.
The engine then sat for 3 years due to unexpected issues in life. I recently rebuilt the carb to insure no stale gas/varnish issues and fired it up. It runs but with consistent muffler explosions. I insured that the distributor was installed correctly ( #1 at TDC with rotor pointing to #1 tower). Timed it to 12 degrees BTDC , no change, still exploding. Rotating distributor full travel, no change. Vacuum gauge at 15 in (in late timing indicator). Ran a compression test, 110 psi across the board. Anyone have a clue as to what the issue could be?