reno27

ok i was installing trick flow underdrive pulleys on a 1994 cobra and i got the water pump and crank shaft underdrive on and the belt would just not go over the alternator pulley so i unbolted the alternator and put on the stock pulley back on and it worked and we drove it around for a while and then on my way home the lights dimmed and no power steering and the alternator light came on and the temperature was really really hot and i shut the car off and the serpentine belt was gone. Is this because the alternator pulley is stock or just because the serpentine belt was shot?

PJC Racing

New pullies will shread used belts due to differences in ridge pattern and sharper edges compaired to the O.E. pullies. You should always change the belt when when you change the pullies.

But didn't you even check the condition belt? You post indicates you didn't.