engine problems, HELP!

having a problem w/ my engine, there's loud pounding rhythmic noises coming from the crankshaft area, and i'm not sure what's causing it. i have checked the flywheel, as well as the crankshaft (still attached to the block), couldn't see any visible problems, can anyone help? thanks!

One idea that comes to mind is that you've got a bad bearing (conrod most likely, perhaps main)... but before you tear down the engine and check that, take a look at your TV damper (it's built onto the crank nose pulley). Those guys can wear out & break, and that'd make a racket too.