Well, I'm by no means an expert at car stuff. In fact, I'm probably a (edit: haha, they filtered out the word n 0 0 b. Oh well) newbie at this, but did you get a new Harmonic Damper to go with that crankshaft underdrive pulley? I've heard that crankshaft pullies don't work with the stock damper and you need to get a new one or else you're going to mess up the engine. Sorry I can't be more specific as to what 'mess up' means, but I don't know