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I want to order some parts from rockauto and thought i also get some new belts for my
1972 Oldsmobile Cutlass Supreme 350 with A/C and power steering with this order.
Well i thought i look at the car before placing an order and it looks somewhat off to the "350 Air Conditioning with Power Steering" graphic above to me?
Its also a bosch alternator. I dont think olds used german alternators back in 72?
They didn't. But no telling what's been replaced in 50 years, for example that metal tube upper radiator hose. No Oldsmobile of that vintage ever left the factory with that.
The intelligent way to go about this is to cross-reference the new belts to the numbers on the existing belts. That or take them off, use a belt length gage to measure them, and get new belts of that length.
Last edited by rocketraider; Oct 19, 2021 at 03:36 PM.
Can somebody tell if the belt drive setup is factory using my pictures?
I mean im 99% sure the alternator isn't but that doesn't automatically mean the belts are different than factory.
If the belt drive (and with that the belts) are different i guess i have to measure in order to find the correct belts?
But do i absolutely have to remove the belts for measuring?
Can somebody tell if the belt drive setup is factory using my pictures?
I mean im 99% sure the alternator isn't but that doesn't automatically mean the belts are different than factory.
If the belt drive (and with that the belts) are different i guess i have to measure in order to find the correct belts?
But do i absolutely have to remove the belts for measuring?
Your belt arrangement looks just like the diagram for A/C and PS that I posted. That is not a factory GM alternator. The only issue is that the pulley looks much larger than what came stock, which will have an effect on the length of that particular belt.
Look at the notes in the diagram Joe posted. You'll see one alternator belt and pulley part # designated as C-49 which is electric grid rear window defogger. I'm guessing C-49 would have had a smaller diameter pulley to increase alternator speed and a corresponding shorter belt. Measure pulley diameter. Someone here will have specs for standard diameter and any optional equipment applications.
Still think the best option is to cross-reference the belt numbers already on the car, especially if they're functioning.
If i see correctly non of the numbers match in a cross reference ?!?
Your current belts are not the factory ones. Obviously they aren't going to match the factory numbers. The diagram I posted are the factory part numbers. Go to RockAuto, use the Part Number Search tab, and key in the numbers from the diagram. For example, here's what you get when you type in the 408310 number for the alternator belt:
Your current belts are not the factory ones. Obviously they aren't going to match the factory numbers. The diagram I posted are the factory part numbers. Go to RockAuto, use the Part Number Search tab, and key in the numbers from the diagram.
The second set is only about 2" greater in circumference. Math is your friend: a 2" larger circumference is about a whopping 5/8" larger on the diameter (and yes, I realize that the belt isn't a perfect circle, but you get the point). There's far more than that much adjustment in the accessory brackets. Stop overthinking this. Either set works. Personally I'd prefer the smaller ones since belts do stretch as they age. The large ones may be fine with the available adjustment when new, but might push the limits if readjustment is needed. Also, whoever installed the larger ones may have had a limited selection on hand, or may not have wanted to worry about sliding the accessories all the way to the minimum travel position to change the belts.
And since your next thread will be about the new PS pump belt squealing, read this:
Originally Posted by joe_padavano
There are THREE fasteners that you need to loosen to adjust the belt, the two bolts on the front and the one nut at the bottom rear of the pump. Once you loosen all three, use a large screwdriver as a pry bar and insert it between the nose of the pump and the tab on the bracket, between the pulley and the bracket. The photo shows the proper position of the screwdriver with the pulley removed for clarity. Use the screwdriver to tension the belt while tightening the two bolts on the front, then get the nut on the back. Failure to do this properly is why there are frequent posts about belts squealing.
