The Stovebolt Site Forums The Parking Lot Big Bolts 302 gmc belt size

My 450 gmc coe with the 302 squeals the belt at high rpm. I've tightend "the wizz" out of the belt, but upon looking at it closer I think that the belt is not the right width. It runs down in the bottom of the pulley grooves. All that is on the belt is a NAPA number(25-11000), but I think that it is a "A" belt or about 1/2" width. I would guess it needs a "B" width belt, but don't know. Does anyone know which width belt is correct and perhaps what length. I've got to pull the alternator again so now is a good time to make the switch. BTW all the belt pulls is the alternator and the fan. Thanks all.
Scott

If the belt is the correct size try belt dressing it works great!

A 302 uses either a 5/8 or a 7/8 belt. If your belt is too narrow, it will slip down into the bottom of the pulley and you never will get it to quit squealing. V belts were made to run on the V. If it has an alternator, it's not original and you may have a narrower pulley on the alternator than the fan and the crank. I would try a 7/8". I think the length is about 46".

Hy Scott's50, the o.e.m. p/n is 2190637 which crosses to Dayco 30445, that is a wide belt which is 44.5" long, hope that helps.

Thanks everyone, I was sure a wider belt was in order and ya'll confirmed that for me. I'll pick one up today and that should cure the problem. BTW I swapped the alternator in when the generator quit, now the alternator isn't alternating, we've really progressed haven't we? The generator lasted 50+ years the alternator about 50 minutes, oh well.

Thanks again,
Scott