You dont want them too tight or your bearings will be the next to go. You should be able to push them down in the middle about 1/4 icnh or so, I dont know what a mechanic might suggest as the proper tightness, its kind of hard to explain because I go by feel. I tighten them pretty much as tight as I can by pulling on the alternator by hand only one my really strong days do I over tighten, but again its kinda hard to explain, for me anyways. Seabronc is watching us talk maybe he has some words of knowledge.