So a friend picks up a vintage "barn find" GTO Convertible and asks my buddy if he can get it running. The list kept getting bigger installing new parts as they arrived including a new complete exhaust system. Previous owner said "it should fire right up". Now after numerous attempts to get spark and get engine to turn over, we tackled one issue at a time. Finally ready, I am inside to turn the key while my buddy primes the carb. Next I hear a large boom which blew one of the new mufflers completely apart. Once my ears stopped ringing we collectively decided the next item to check on this "it should fire right up" engine was the timing gears and chain. Found some play in the chain which possibly allowed movement from top dead center as we turned over the engine and allowing it to fire on the wrong stroke. Replaced the timing chain and gears along with a few other new parts. Engine now runs great. Also replaced the muffler so I took the damaged one and made a one of a kind garage shop desk lamp that will have a back story several of us will remember.