A6 Compressor Pulley Size

[Larry M.]

Re: A6 Compressor Pulley Size

Dom------


I would not get too upset about this. This is a forum for learning. If we all put our minds together maybe we can figure this out. That's really the fun of it. This is a hobby, not a religion.

By the way, I am particularly interested in the compressor pulley size for any 1965-68 with L-79, especially if the compressor and components are known-original. There's just got to be some of you out there with such an application that can report on this.

Joe:

I will measure my car today. A 1967 327/350 HP with original dated compressor. I will report later today.

Larry

[Dick W.]

Re: A6 Compressor Pulley Size

Dom------

Well, I suppose it's possible that the 63-64 GM #5914724 was a 6-3/8" pulley. I have no information on it.

Otherwise, if there was a 6-3/8" pulley used on Corvettes, then it was a pulley that was never available in SERVICE. That would be extremely unusual but I suppose it could happen.

According to GM, the 5.0" GM #5914745 was used for most 1964-68 Corvettes.

1964 327/365 used the 6 3/8" pulley. The later cars including the 454's used the smaller pulley. It is very a very obvious difference when you raise the hood.

[Terry M.]

Re: A6 Compressor Pulley Size

Dom------


This is a hobby, not a religion.

Can we get an Amen to this?

[Larry M.]

Re: A6 Compressor Pulley Size

Joe:

Went out to the garage and measured the AC pulley diameter on my 1967 327/350 HP car. Car is VIN #14845 and build last few days in March, 1967. Fairly original car with only 27,000 miles.

AC label shows Model # 5910645 with a compressor build date of 012672 (January 26, 1967......second shift)

Front hub of compressor clutch is approximately 4.280 inches and the belt pulley grove OD is 5.780 inches. The depth of this groove is 7/16 to 1/2 inch.

Hope this helps.

Larry

[Dick W.]

Re: A6 Compressor Pulley Size

can we get an amen to this?

amen!! amen!!amen!! amen!!

[Domenic T.]

Re: A6 Compressor Pulley Size

Dick,
Can't do it unless you are good with wrong parts.
I measured TODAY, All the vette compressors that judges over look. Here is what the pulley size measures for the first 7 out of a bunch.
YES, they are not 5 3/4, actually closer to 5 1/8, FAR from 5 1/8 which = 5.125.
What I have is what all called the 5 3/4 pulley which was actually closer to 5 5/8.
#1- 5.620, # 2- 5.545, #3-5.631, #4- 5.650, # 5- 6.320, # 6- 5.643, #7 was a repo bought rears ago 7.750.
Now 5.6125 is = to 5" 5/8" .....5.750 is = to 5 3/4"..........# 3 is .006 over 5 5/8. These are ALL measured from the OD which is the outer
diameter, Lip to lip.
Wayne Midcliff had a post that he referred to as a CORVETTE parts book! My guess is that it is NOT a passenger car parts book . It showed the 5914745 15-216 pulley. Punch it up and look at the size.
Dick, AMEN, who cares any way!

Dom

[Joe L.]

Re: A6 Compressor Pulley Size

Dick,
Can't do it unless you are good with wrong parts.
I measured TODAY, All the vette compressors that judges over look. Here is what the pulley size measures for the first 7 out of a bunch.
YES, they are not 5 3/4, actually closer to 5 1/8, FAR from 5 1/8 which = 5.125.
What I have is what all called the 5 3/4 pulley which was actually closer to 5 5/8.
#1- 5.620, # 2- 5.545, #3-5.631, #4- 5.650, # 5- 6.320, # 6- 5.643, #7 was a repo bought rears ago 7.750.
Now 5.6125 is = to 5" 5/8" .....5.750 is = to 5 3/4"..........# 3 is .006 over 5 5/8. These are ALL measured from the OD which is the outer
diameter, Lip to lip.
Wayne Midcliff had a post that he referred to as a CORVETTE parts book! My guess is that it is NOT a passenger car parts book . It showed the 5914745 15-216 pulley. Punch it up and look at the size.
Dick, AMEN, who cares any way!

Dom

Dom------

I think the slight variations in pulley size must be due to variations in the as-cast pulleys. There just can't be that many actual GM pulleys of all those slightly different sizes. I suppose it could also be that some are aftermarket and they made their pulleys to a slightly different size.

In that regard, my post #5, above, was in error. The sizes for the GM #5914745 and GM #6550750 were reversed. The correct sizes are as follows:

GM #5914745-----GM spec 5.58" OD---actual measure is 5.65"

GM #6550750-----GM spec 5" OD-----actual measure is 5.13"

The 6-3/8" pulley must be the GM #5914724 which I have no dimensional specs on. GM says this was used for 1963-64 with HP (HP for 1963-1964=300 horsepower). Although not so cataloged, it was probably also used for 1964 L-76 with C-60.

Based on what Larry reported above for his 1967 L-79 with C-60, I'd say that the larger pulley size was not used for L-79, at least for the 1967 model year and, I suspect, for the whole 1965-68 period. Although his pulley appears a little larger OD than the GM #5914745, I'm pretty sure that's the pulley that was installed and, curiously, it's exactly what GM says was installed for all 1963-68 L-78 except 63-64 with HP.

[Leonard M.]

Re: A6 Compressor Pulley Size

Hi Mark, Here's pictures from my very low mileage '72 454. Looks like 5 1/8"

[Mark E.]

Re: A6 Compressor Pulley Size

Thank Leonard! Very helpful. This is the pulley currently on my '70, and the pulley size I saw at the 2017 Nationals on a three or four 70-72 454s.

So I conclude that at least some of these cars originally had a 5", 5 1/8", 5 1/4" pulley (measurement variation for the same pulley).

[Rocco S.]

Re: A6 Compressor Pulley Size

I would like to add to the discussion. I have a low mileage (55,000 mile) unrestored 1967 A/C coupe with L79, M21 and 3.70:1 posi. I know it has the original compressor since I purchased from the original owner and the compressor still has the encircled "OK Final Test" and "CHEV" yellow ink stamp on the side. The pulley OD measures 5.645" (roughly 5-5/8").

The back plate has a date code of "K26" and a cast-in part number 6555392 (hard to read). The label says Model # 5910645 and a date code of 022272 (Feb 22, 1967?). My car is also a late March car.

No one talked about how rear gear ratio may have been a deciding factor in compressor pulley size. I know on other GM muscle cars of the day that A/C cars were limited to rear ratios of approx. 3.23:1 to maybe 3.55:1. I assumed that GM was concerned that at highway speeds the compressor would over-speed causing failure and warranty issues. Another way around this problem would be to use a compressor with a larger pulley, which essentially slows the compressor speed down.

[Dick W.]

Re: A6 Compressor Pulley Size

Dom------

I think the slight variations in pulley size must be due to variations in the as-cast pulleys. There just can't be that many actual GM pulleys of all those slightly different sizes. I suppose it could also be that some are aftermarket and they made their pulleys to a slightly different size.

In that regard, my post #5, above, was in error. The sizes for the GM #5914745 and GM #6550750 were reversed. The correct sizes are as follows:

GM #5914745-----GM spec 5.58" OD---actual measure is 5.65"

GM #6550750-----GM spec 5" OD-----actual measure is 5.13"

The 6-3/8" pulley must be the GM #5914724 which I have no dimensional specs on. GM says this was used for 1963-64 with HP (HP for 1963-1964=300 horsepower). Although not so cataloged, it was probably also used for 1964 L-76 with C-60.

Based on what Larry reported above for his 1967 L-79 with C-60, I'd say that the larger pulley size was not used for L-79, at least for the 1967 model year and, I suspect, for the whole 1965-68 period. Although his pulley appears a little larger OD than the GM #5914745, I'm pretty sure that's the pulley that was installed and, curiously, it's exactly what GM says was installed for all 1963-68 L-78 except 63-64 with HP.

Joe from what I have observed over the years, the larger pulley usage ended 1964 m/y along with A/C on solid lifter engines. The only solid lifter engine built with A/C after 1964 was the '72 LT-1 and it used the standard size pulley that the small block and big block engines of that era used.

[Larry M.]

Re: A6 Compressor Pulley Size

Joe from what I have observed over the years, the larger pulley usage ended 1964 m/y along with A/C on solid lifter engines. The only solid lifter engine built with A/C after 1964 was the '72 LT-1 and it used the standard size pulley that the small block and big block engines of that era used.

Dick:

NCRS JM and Noland both say that 327/365 SHP solid lifter engine with AC was made in 1965 also. "HK" engine code.

I am certain you just forgot this bit of trivia.

Larry

[Dick W.]

Re: A6 Compressor Pulley Size

Dick:

NCRS JM and Noland both say that 327/365 SHP solid lifter engine with AC was made in 1965 also. "HK" engine code.

I am certain you just forgot this bit of trivia.

Larry

At my age I am lucky to remember how to turn the computer on.