about a month ago i had readjusted my valves and after all the cranking to find tdc i guess when it started a loud explosion happened out of the exhaust (louder than a shotgun) and blew a hole in my rustmaster. Car started after that and its running fine, but im wondering if i did any damage?? Because a week ago the same thing happened to my buddies cutlass and it cracked 2 pistons

bumping the motor over probably flushed some fuel into the exhaust, then when you started the car it ignited in the exhaust causing the explosion, no damage to the motor, its made to withstand combustions, the muffler, on the other hand...

detonation will f-up a motor, its caused my too high compression or crappy gas, ect, nothing you did would cause it.

that was my conclusion also, but i only began to wonder after what happened to my buddy

yeah wheni first started my motor i had the timing way off and had it backfire like that...very loud, shotgun blast.

no worries man, poor muffler tho

if you ever crank it over like that with starter, disconnect coil plug wire so no spark gets thru