Belts and pulleys

[chewychevy67]

Ok I have located all my original pulleys for my 67 and ordered new belts for it. They all line up correctly but my ac pump and smog pump pulleys are deeper than the rest. Now my ac belt was larger than the rest (I used gm restoration belts correct for the applications) and the belt sits nice in that pulley but stand out of the water pump and crank pulley slightly. Alt and power steering are just fine. My smog pulley is deep like the ac is but the belt I got was a 3/8 and surs really deep in it but fits nicely in the crank and water pump pulley. Did gm make it like this? I could use a different pulley on my smog pump and the belts would all be the same but not on my ac pump.

[chewychevy67]

If I run a thin belt on my compressor it rides deep in the pulley like the smog belt but sits properly in the water pump belt. Which is better. These are all gm pulleys so is this how they designed it?

[Sheepdip]

Not all belts are created equal....my stock GM factory A/C, Alternator and Power Steering all fit and run best/correct on Gates Belts.

In fact I just changed out a O'Reilly's stretchable rubber band on my A/C Compressor to a Gates and the squeal/screech at higher pressures (in town) went away.