knocking in motor

that I cannot seem to figure out yet. I have an 84 GT and after about 15 minutes or so, I hear a knocking coming from the engine. It is not the lifters, this is a deep thud sound. If I accelerate the motor, the knocking accelerates as well. The only thing I changed were the pullies, intake and carb.. Could I have done something to throw something out of whack by changing the pullies from stock to Underdrive? Is there any test I can do that would narrow down my possibilities. I really don't want to pull the motor considering summer is almost here. (depending on the day). I can really use some expertise here. If anyone is in the Montreal/ Chateauguay (quebec area) and could maybe swing by to lend their knowledge, I would greatly appreciate it.

suspect con rod brng or collasped piston ya foctard

BTW FRENCHIES SUCK

hurc ast

Sounds like maybe con rod, or a bad mains bearing. Years ago I had a bad con rod in my 82 GT and it was most obvious at idle. That is until I snapped the crankshaft at the #2 mains (teardown showed bad rod bearing at #5 and it was bad enough to be relatively certain is was the culprit). So much for shitty cheap rebuilds - an expensive, but important lesson to learn at 18. I built/blueprinted and had balanced a new shortblock with arp fasteners and it spun smoothly to 6200 for years.

I have also heard of weird stories where bad harmonic balancers would hit against timing pointers and such causing knocking noises. I would