As the Chevy 305/350 don't have belt tensioners you need to loosen the alternator and A/C comperssor and using a pry bar pull them until there is less then 1 cm of bounce in the belts the retighten them.
with bolts and tighten
100 INCH pounds.
usually serpentine belts get their tension(tightness) from the belt tensioner
I've got a better question, why is this question in the Chevy venture forum ? they have completely different engines and belts
With cast iron heads it is 30 lb/ft. Tighten in a criss cross pattern.
The ac, power steering and alternator will have separate tensioners (the units slide on a bracket to tighten) if they have separate belts. Loosen the units and the belts will come off. If a serpentine belt is used there only one tensioner.
Depends on which car and which belts.
You're going to need "The Book". A factory service manual (FSM) for your vehicle is the best. .
Tighten the belts
No, the 1957 Chevy didn't come with seat belts.
Depends if it has a tensioner, or the older type manual adjustment. With a tensioner, put the correct socket on the pulley and depress it by hand until you get the belt changed. the manual style, loosen the bolts holding the slide, push in on the alternator to change belt, reverse to tighten.
Mine was doing the same thing and all i had to do is tighten the belts, so try checking the belts and make sure they are tight so it can function properly.......give it a try Hope it works