[Andre]

I'll take a look to the best of my hobbled ability. I'm on crutches for 2 weeks, then surgery. I'm certain my compressor is whatever unit was available when I did the car. The OK stamp was added by me so it has no value. I'll try to take picture of belt crank with a/c belt and measuring tape. I've probably had 15-20 crank pulleys for 64-7 with a/c, and those added a single groove pulley and it was the same width as the other grooves. 64 of course did not add any additional crank pulleys to my knowledge right? We certainly can't be the only three who have pulleys for us to compare

[War eagle]

The shaft is a 1/2in drill bit that fits perfectly in the top portion of the groove.

[John V.]

I keep thinking the big Pontiac guys can add to this.

I also have never seen a p/n stamp on the '64 W.P. pulleys, so pretty certain none on mine whenever I do find it.

My p/n id is circumstantial. The '64 GP the engine was pulled from showed A/C code on the Data Plate.

The water pump pulley was the right size, 2 different size grooves. So that was the basis for the p/n ID.

I also have an original '64 Balancer but it is the non-A/C unit. Earlier in this thread I posted that I had the A/C Balancer. Not so, I crossed it up, had the A/C W.P. pulley but not the Balancer.

I know of lots of MPC errors. If the description of 9772317 was wrong from the start, I agree, it likely would have stayed wrong right to the end.

My point was, they may have described the 9772317 incorrectly. But I seriously doubt that every other A/C belt was also incorrectly described as 1/2" if in reality none of them were.

And I also seriously doubt that the '64 would have been the only year using a narrower belt if all others did use the 1/2"

And finally, it seems very unlikely that the AMA specs, would show the width as .47 for the Tempest A/C belts and all others as .38. Probably not especially useful to mention that the '64 Tempest Shop Manual also identifies the A/C belt as 1/2".

Another item. SCN #3-1965, pg. 26.

Applies to '65, not '64. Refers to the release of a 15/32" width for use as a PS drive belt.

This belt would be used interchangeably with the 3/8" PS drive belt.

Revised belt tension is noted.

The point of interest, the A/C compressor belt for both V8 and 6 cyl applications is also listed in the chart and is shown as 15/32.

And 15/32 equals .46875. Rounded off, .47 as listed in the '64 Tempest AMA specs.

I don't know how or why they did it, but all of this convinces me that that the A/C belt used in production was NOT 3/8.

[War eagle]

John I agree.

MORE useless info: My compressor end plate is cast E 4 4 and came with my goat as did the pulleys. I have no doubt these are original 64 parts.

I have a call out to a friend who works at goodyear and maybe he has an old belt spec book. I think I recall Goodyear as the OEM. to GM. (at least in that era)

[bill ryder]

I have an OEM 539208 belt for 64 alt. It is embossed GM 539208 and made by DAYCO. "Bill"! Also embossed 3-4 which could be a date code??

[Andre]

If war eagles parts all came with his car originally, then I tend to agree that those are correct, especially the compressor.
Its apparent from your pics that your crank and compressor have the 1/2" groove, but why isn't the water pump matching those 2? How will the .47 belt that fits those going to work on the 3/8" front groove of the water pump pulley? Or does this mean there really is a water pump pulley with a 1/2" groove?

[John V.]

Andre, that is why I thought the SCN info about the '65 V8 PS drive belt was pertinent.

The SCN was announcing the release of a 15/32 width PS drive belt. It noted that the new wider belt would be used interchangeably with the 3/8 PS drive belt in production. The SCN provided revised tension values for the 3/8 belt, noting that it would now be the same as for the newly released 15/32 belt. The revision was based on recent test data and was necessary to avoid slip and in some cases belt squeal.

No change to the WP pulley.

The 15/32 width A/C drive belt had been working in the front WP pulley groove, apparently the new 15/32 width PS belt would also work in the rear WP pulley groove.

Since the front & rear WP pulley grooves are same width, all I can add is that it MUST have worked with the 15/32 width belts, else PMD would not have done it.

While the SCN only applies to '65, if you compare the '65 W.P. pulley groove width to the '64 W.P. pulley groove width, I'm pretty certain they are identical.

The idea that preventing slip and squeal as the reason for the revised (increased) belt tension and release of the wider belt suggests that perhaps the groove width of the pulley might actually be a little "loose" for a 3/8 belt.

It is odd that the Belt Chart in the '66 MPC (pg. 249) does not list any 15/32 belts. It does list several 13/32 belts. I'm wondering if at least some or maybe all of the belts listed as 1/2 are actually 15/32.

I don't see a p/n in the '66 MPC for a 15/32 PS belt for '65. But I do note that the PS belts for '66 are listed as 1/2, and perhaps it too was 15/32 (.47).

That tiny change from 1/2 to 15/32, all else being equal about the pulley groove, means the 15/32 belt will ride lower in the groove than a true 1/2 belt.

And if I assume the groove width is actually a hair wider than 3/8, say 13/32, then redoing the math I did earlier in the thread, the belt would now ride right at 3/32" up out of the groove.

The 5/16" depth belt would be in the groove by 7/32" using these assumptions which would be plenty.

Even if the groove width was 3/8" on the nose, the 15/32 belt would still ride 11/64 down in the groove.

And I think I am not accounting for the effect of belt tension which should force the belt even further down in the groove, the tightening needed to prevent slip and squeal.

Looks to me like the 15/32 belt width makes perfect sense and apparently did to PMD as well. W.E.?

[War eagle]

I too have been doing the math and agree with your tabs. Basically from the widths of .375 to .440 to .470 and finally .500, there are .030 thou increments. I said earlier that something a bit larger than the 3/8(.375) would seem to work well in both pulleys so I rallied with the 9433775 (.440) as the supersede of 9772317. A .440 to replace the 1/2inch 64 belt? That would be .060 thou under or .030 per side. You mention that 64 and 65 w/p pulleys share the 3/8 groove. (but not the same pulley) I have both here and will check later on their widths. By 1982 anyone that needed a 64 A/C belt would have a worn pulley and diminishing the width down .060 thou from 1/2in does not seem the correct way to go. However, engineers are bound to always do a supersede, which assumes fresh new companion parts, as originally manufactured.
AGAIN. Of 4 original looking(who knows for sure) 64 full size Pontiacs, ALL have the double 3/8 grooves at the water pump. ALL have the 1/2inch wide crank and compressor groove. The ONLY water pump Pulley for A/C equipt V8 Pontiacs, as shown in the belt usage diagrams, is the stepped double pulley. No other stepped pulley is indicated or found in the MPC. ONLY 1. If a stepped 1/2 X 3/8 water pump pulley surfaces, that does not make the 3/8 X 3/8 go away OR explain what it is used on.
FWIW: The 1963 Tempest 326 w/a/c uses the same 544594 w/p pulley and a 1/2 X 62 belt 534311.

[John V.]

W.E., I don't think there is another '64 W.P. pulley for A/C. I assumed in the beginning that there must have been a pulley with mismatched grooves because I assumed the front groove had to be wider.

I think that has been soundly disproven. Same grooves front and back is correct.

The thing that I didn't count on was two different width belts riding in the same width W.P. pulley grooves.

Don't forget, the '64 Tempest AMA specs also says the A/C belt is .47, so the '82 replacement belt at .440 is really only .030 under.

I think the question is why did Pontiac describe the 15/32 belts as 1/2" in the MPC. I don't think we'll ever know the answer to that.

The '65 SCN is evidence enough that they were actually 15/32 in production.

I'll be waiting for your confirmation about the '64 groove widths vs. '65.

I don't know how you will ever convince a concours judge, but IMO, the correct A/C drive belt for you to use is p/n 9772317 and it should be 15/32" width. Not 1/2" and not 3/8".

FWIW, I mentioned the '63 T8 application in post #4, including the fact that belt 534311 has a much taller cross section (17/32 vs 5/16) per the belt chart dimensions. In the end, I don't think any of that proved useful. I think we took a long and circuitous path to discover the correct info. I hope I was helpful, I don't even have a dog in the fight, only wish my '64 was A/C equipped!

[War eagle]

I examined the 65 GTO set up and as expected the w/p pulley would have two 3/8 grooves but BOTH outside diameters are the same. (no step). The crank balancer/pulley grooves are the same O.D. BUT-----3/8 grooves on both. Remember the 64-65 uses the same 1/2 x 62 #9772317. The compressor is of later production having a heat/temp cutoff switch but still an A6 with a 1/2in groove. The 62 thru 66 compressor pulley & bearing assy #6590710 I believe extends even further into the 60`s and having the 1/2in wide groove.

What I need is to have a 65 owner with factory a/c verify the 3/8 X 3/8 crank pulley for width of groove. It was also expected that since the w/p grooves were both the same O.D. , that the crank would also have to be the same diameter as the w/p in order to not 'fight' each other. However the surprise of 3/8 groove is surprising.

[War eagle]

I examined my 1969 MPC Corvair, Chevy II, Chevelle and from 1962 thru 1969 these cars used a 15/32 a/c drive belt.

[Andre]

I don't have a 65 AC car, but I do have 65 AC crank pulleys. Its an odd pulley setup with the diameter of the forward most pulley being a smaller diameter. Again if I can get to my stuff on my knee scooter, I'll take some pics. That '65 a/c crank pulley set up was a tough one to find, and then when I did find it, I found 2 or 3 of them. Then some guy had a 65 GTO with a/c, and switched the whole thing to aftermarket a/c, and I scored a few more key pieces.

[War eagle]

. I hope I was helpful, I don't even have a dog in the fight, only wish my '64 was A/C equipped! [/QUOTE]

John I wonder how many converts in 64 got a/c? Probably more than one would think in areas like Fl. TX. NM. AZ. SoCal.
But I also wonder how many tripower manual shift A/C cars were out there in 64. Does any conclusions surface with the many build sheets in your collection? I have always thought a performance car, was about performance and that is how the car was advertised. If one wanted a/c or a high po car, deep groove pulleys were sometimes included, for a purpose------just like having the 3.90 rear but required the addition of special cooling components. It appears everything from a 6 cyl to the tripower with close ratio could be had with A/C and no deep groove provison. (The steep 3.23 rear gear as std.with gto a/c and altered from the original 3.55 std gear of course was on purpose)

In the Zazarine book I noted that a real picture of a 65 compressor that shows a belt very much lower in the groove. Maybe the compressor groove is wider/deeper to hold the smaller 15/32 belt given its distance from the driving crank pulley helping to prevent belt throw. At 13/32 I would be happier. (I can`t seem to relocate the picture)

I called on the advertised repro belts at PY and asked about the belt they claim is for the a/c. I might just as well called the "Institute For The Totally Wrong."

I think we need an original 9772317 belt to measure.

[ron cozzo]

Since we're talking '64 A/C belts as well as pulleys in this thread, I thought I would add some modern belt info.

I ran the repro belts from Quanta, but they kept flying off every time I'd hit the tripower.

So, here are good part numbers for modern AC Delco belts.

Alternator with A/C and PS: 15590, 13/32 x 59-5/8

A/C: 17620, 15/32 x 62-3/8

These stay on when the RPM's climb, so far.

In all fairness to the repro belts, I probably did not have them on tight enough. I did buy a belt tension gauge and properly tightened the new AC Delco belts. It's surprising how hard you have to pull on those belts to get them to spec.

[War eagle]

So Ron give us the pulley groove widths from your car. Thanks for the Delco belt info.

[ron cozzo]

Alt pulley, 3/8. PS pulley, 3/8. A/C pulley, 1/2. Water pump 3/8 and 3/8. Crank 3/8 and 1/2.  

I've got extra water pump and crank pulleys off of 64's. Same.‎