I had all of the serpentine parts from a v8 swapped s-10 so I decided to put them on my TA when I gave up fixing rust. Anyways, everything looks fine and all of the pulleys are fully engaged except the belt comes out of the groves on the crank pulley. It still spins everything but only half the belt is on.
I tried a new tensioner and a new belt but it still falls off. The brackets are from an 89 TA. I'm out of ideas on it, but I don't want to drive around with the belt only half on the crank pulley. I got new AC lines and a compressor and already modified the wires so I'd rather not go back to V belts.

 

Sounds like you have a pulley alignment problem.

 

Do you have the correct balancer and pulley? Is the balancer fully seated?

 

get a laser pointer to align the belts, put it square on the accessory pulleys and check ifn they are aiming dead straight at the crank pulley. With different damper thicknesses you can run into problems. I've had to shim the brackets to align it properly on some of my builds.