Which v belt do i need

Zebbman

Not-quite-so-new-guy
Thread starter
Mar 13, 2021
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Your 86 Cutlass VIN Y should be this belt-
9433757 7/16 x 52.5" - This A/C belt was used on the single belt P.S. pump setups along with the single belt from water pump to alternator setups for 307 Cutlass. (see the video- it shows a similar setup). You can tell easily by the single groove P.S. pump pulley and 2 different sized water pump pulley grooves.

9433756 7/16 x 52.0" - This A/C belt is called out for the DUAL belt P.S. pump setups with part of the alternator belt running around the front groove of the P.S. pump. This setup was used on SOME Cutlasses mid-84 production and up, mostly VIN9, and IIRC, the Diesels.

Some aftermarket belts come with the length size in their part number. Examples you gave was the 520 and 525 belts. 520 equates to 52.0" and the 525 equates to 52.5".

Obviously it doesn't have to be a GM belt, I'm just throwing the p/n's out there as to what the sizes of the belt are. Pick the one best for you, and you should be golden.

Good luck.

Edit: I went back and looked at the video and I thought I saw that A/C belt number was 15585. I'm like "dafuq"?? That seems weird. Then I realized it was likely a Custom Cruiser setup with the A/C belt driving the A.I.R. pump too. Errrgh. 86 Cutlass drove the A.I.R. pump via an extension pulley off the crank specifically for this, as did many others. Olds used about 43 different belts in the 80s and early 90s on the 307s.
Super informative. I'm going to give the 525 belt a go and see. I compared the old with the 520 today and the difference is minimal but obviously enough to make a big difference. I just got it back from having leaky manifold gasket replaced so these are the the only things I haven't replaced. I did look at that video as well and as you correctly stated I have the A.I.R pump on its own belt. I will note all the belt sizes once I have them correct for future reference. New to the Oldsmobile scene but I got a super nice car here so just want it correct. Thanks again.
 
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ssn696

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This 307 came from an 87 Cutlass with 46K on it. A couple might be the factory belts. The air pump belt is an oddball one, narrower than the others.
 

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Zebbman

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Mar 13, 2021
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Gentlemen I thank you. The pictures were super helpful as well. The 52.5 inch belt is on. This is on an 86 cutlass supreme 29000 original miles but it sat in a garage for years before I inherited it. The belts were all different and since I'm somewhat over the top and didn't know condition I wanted them all the same and new. Everything else was original parts that have all been replaced. Plugs, wires etc. Peace and again thanks.
 
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69hurstolds

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Jan 2, 2006
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This 307 came from an 87 Cutlass with 46K on it. A couple might be the factory belts. The air pump belt is an oddball one, narrower than the others.
The air pump one is a little skinny runt. The PS belt on your 87 pictures is aftermarket. 44.0". The PS belt actually was a 7/16 x 44.5" nominal belt, p/n 9433741.
WP to alternator should be p/n 22524186, and it was a 3/8 x 43.0" (the 430 aftermarket belt on there is the same size replacement).

The other 2 belts are factory belts. The A/C which was discussed being 7/16 x 52.5", GM p/n 9433757, and the A.I.R. pump 9433847, 5/16 x 46.5". This is for Zebbman so he'll know what length of belts came on his car originally.



And for you late 84 H/O (LV2-9), and 85-87 442 (LG8) guys out there...

The alternator belt p/n changed in the late 80s from 469595 (3/8" x 55.75")to 9433764 (3/8 x 56.0"). Sometime in the 90s, the PS belt changed from 9433640 (3/8 x 45.0") to 9433743 (7/16 x 45.5"). The A/C belt was 9433756, 7/16 x 52.0" and the A.I.R. pump belt remained the same, 9433847 (5/16 x 46.5"). Confused yet?
 
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Zebbman

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Mar 13, 2021
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Much less confused than I was thats for sure. I wrote all that in my notes that I have kept while bringing this car back to life. Thanks again for the great info
 

ssn696

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Jul 19, 2009
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Connecting to a past dot...
 
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g0thiac

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Sep 6, 2020
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g0thiac

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Sep 6, 2020
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That was only for the 78-80 A-body 442. 79 H/O and 80 442 was the last gas 350 Olds in an A-body.
Damn. Whoever at GM corporate that thought "Yeah just use the 307, no big deal" was smoking some of the best crack out of the 80's it seems.
 

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