Oil leaking from crankshaft pulley

[boojus]

after putting on a new scat aluminum pulley and installing the engine, oil leaks pretty bad from behind the pulley. i tried reinstalling the old stock pulley but the oil is still coming out at a rate which is upsetting. Ive tried cranking it down tighter than ****, but it still decides it wants to leak. any suggestions on how to stop or at least slow this leak?