C3 alternator and A/C compressor sources

[Ralph A.]

Can anyone tell me if the following were used on anything other than the Corvette. Trying to locate these so the car can be judged.

1971 350hp Auto, A/C, PwrB, Pwr Steering, build date 4/5/71

Need
Alternator 1100544 date codes 0K, 1A, 1B or 1C, will take any date.

A/C Compressor 5910778 date codes 01011 thru 03311, will take any date.

Any good rebuildable core I am interested in.

Thanks
Ralph

[Joe L.]

Re: C3 alternator and A/C compressor sources

Ralph-----

I can find no other application, at all, for the GM #1100544 alternator beside the Corvette application. In addition, it was never available in SERVICE.

I can't find any info on the compressor, as far as other applications. I'm pretty sure that there were some, though.

[Dick W.]

Re: C3 alternator and A/C compressor sources

The alternator is very hard to find, just keep looking. Advertise in the NCRS Driveline want ads. The compressor will be like hunting a needle in a haystack. There are plenty of compressors out there but chances of finding what you want are verrrry slim. You will probably end up buying a new or rebuilt A-6 compressor and using a repro label.

[Jack H.]

Re: C3 alternator and A/C compressor sources

Joe, the '778 AC compressor is one of those Corvette 'mystery' items I've pursued but never resolved. You may not know this but nobody makes a reproduction of that compressor label. My copy of the AIM shows the change from '741 to '778 compressor occurred shortly after/during the '71 MY change over (AIM date 8/10/70). Hence, you'd think there'd be oodles of the willey critters running around out there.

BUT, I've never seen one. Plus, I went through Paragon years ago when Richard Fortier was still at the helm. He supplied me with phone numbers for the different folks who supplied AC labels for him. I followed up and, yep, nobody made a '778 label. Further, MF Dobbins told me he knew about the '778 and the reason why he didn't offer a repro of that label was he required a bona fide original to look at/verify and in all the years he'd been in the repro label business he'd NEVER seen one.

I wonder if the '778 was released to production, but not ordered due to the existing on-hand inventory of '741 compressors. Then word trickled down that the '72 cars would be going to A6 compressors with the super-heat switch in them (different assy that wouldn't carry over from '71 to '72 because of the wiring harness change) and St. Louis simply failed to build/ship '778 compressors? Anyway, it'd be interesting to see if anybody out there actually has a '778 or someone like Art Armstrong can comment further on what looks like an anomoly....

[Mark #28455]

clutch assembly different

Wasn't the actual compressor the same for all the passenger cars (other than the sticker with the part number)? I heard somewhere that the clutch assembly was unique to Corvettes and Cadillacs - anyone else heard that?
Thanks,
Mark

[Joe L.]

Re: clutch assembly different

Mark-----

The A/C clutch drive used for Corvettes was not unique to Corvettes and Cadillacs. The same clutch was used across all GM car-lines.

Also, the Corvette compressor was not unique, at all, to Corvettes. It was used in many other GM car lines, too.

[Mark #28455]

Thanks Joe! *NM*

[Jack H.]

Hum...

what Joe says differs from my experience. Per my experinece, the Corvette A6 compressor differed in two respects to equivalent compressors used on Chevy passenger cars equipped with Four-Seasons A/C systems:

(1) The clutch was 'clocked' on the compressor input shaft such that the electrical connectors came off the RH side vs. passenger car compressors (mounted on the opposite side of the engine) with the electrical connectors oriented to the LH side of the compressor.

(2) The Corvette version of the A6 had a smaller refigerant capacity (3 lb, 4 oz) than the Chevy passenger car version of the A6 (3 lb, 12 oz) due to the smaller cabin size of the vehicle.

To my knowledge, NONE of the aftermarket rebuilders distinguish and all rebuild compressors with the larger capacity (one part fits all) with virtually everyone clocking the clutch according to pass car norms vs. Corvette. No big deal on the clutch clocking--you simply pull the front pulley and 'flip' the clutch electro-magnet to its alternate position.

On the internal capacity of the Corvette A6 compressor, it was NOT 'really' unique to Corvette as the same compressor was used in 'Chevy' air conditioning systems vs. Four Season season systems. The Chevy A/C system was the dealer installed kit (mounted under dash) available for cars and trucks originally built without factory A/C. Having a larger capacity compressor in your Corvette won't hurt anything as the system is self-throttling to regulate refigerant flow and prevent the evaporator from freezing over....

[Joe L.]

Re: Hum...

Jack-----

The compressors for Corvette applications of the 60s and early 70s were the same as the compressors for many other (but, not all) applications. However, the compressors as sold in SERVICE and as used in PRODUCTION are different and have different part numbers. That's for this reason: the compressors sold in SERVICE as a NEW compressor were usually, if not always, supplied without a clutch. The compressor used in PRODUCTION was supplied with a clutch. The part number on the unit is the part number for the complete assembly. Since the PRODUCTION assembly was never sold in SERVICE, you could not ever get that part number on a SERVICE compressor. By the same token and even though the compressor portion of the unit was the same, the SERVICE compressor had the part number for compressor sans clutch and this number was never found on a PRODUCTION unit.

So, the point is that the complete assembly, as used in PRODUCTION, may have a part number unique to Corvettes. But, that's only for the exact reason that you described-----like a difference in "clocking" of the clutch to the compressor or other minor differences for the Corvette application. The basic parts are the same as other applications. The part number found on the PRODUCTION unit is specific to a certain configuration or aggregation of parts as used in PRODUCTION. This configuration and/or aggregation of parts may be unique to Corvette but the component parts are not, at all, unique to Corvette.

With REBUILT compressors, things are different, even if it's a GM/Delco unit. Many rebuilt compressors (but not all) are supplied WITH a clutch already installed. These have a totally different part number since GM/Delco REBUILT units NEVER, EVER carry the same part number as a NEW unit. Of course, a REBUILT unit is never, ever used in PRODUCTION.

[Jack H.]

Re: Hum...

Sounds like we agree on the clocking of the clutch electro-magnet on a COMPLETE compressor assy. Lots of talk above about service vs. production, but no rifle shot regarding the internal difference(s) between a factory original Corvette A6 and the corresponding Chevy passenger car A6 supplied from the factory when the Four Seasons AC option was ordered which is the second point I was trying to make, Joe. Maybe I stated it wrong by rattling off the R12 capacity of the compressor....

So, let's go another step and read what the '71 CSM book has to say in its air conditioning section:

"The same basic six-cylinder reciprocating compressor is used in all systems. Two variations of the basic compressor are used. One, with a displacement of 12.6 cu in, is used with the Four-Season System (except Corvette) and Comfortron System. The second model, having displacement of 10.8 cu in, is used with the Corvette Four-Season System and all GM Chevrolet Air Conditioning Systems."

Based on this, I was trying to add on to your thread in the chain that said the compressors were essentially the same by clarifying there were internal differences between Corvette's A-6 and those installed on corresponding Chevy passenger cars.

A 10.8 vs 12.6 cu in displacement difference is approximately 14% less which implies different internal components. What did I miss?

[Joe L.]

Re: Hum...

Jack-----

You will note that in a previous post I said that the Corvette compressor had other applications besides Corvette. I was not, of course, referring to any of the "add-on" type system applications; I was referring to PRODUCTION applications only. What I said remains the case. The same compressor as used in Corvette was used for MANY other applications. Included among those were 62-67 Chevy II, 73-75 Vega, 62-66 Chevrolet and GMC truck with factory A/C, and other applications for Buick, Oldsmobile and Pontiac. I would say that qualifies as a LOT of other applications for the same compressor used for Corvette. Consequently, the Corvette axial compressor was decidely NOT unique to Corvette applications.

As far as the answer to the question about what you missed, I don't have an answer for that.

[Joe L.]

Re: Hum...

Jack-----

I thought that I'd respond to your e-mail here inasmuch as the information may be of interest to others following this subject.

Regarding the issue of 1971 Corvette compressors, yes, I was definitely speaking in a much broader sense than just 1971 when I said that the same compressor used on Corvettes was not unique to Corvettes and was used on other models. I was not, necessarily, referring to other 1971 models. Quite frankly, it would have made no sense, at all, for me to be speaking in terms of 1971 Corvette models versus other 1971 models. The fact is that the compressor used on 1971 Corvette models was used for many other Corvette year models and many other Chevrolet models and many other GM car and truck lines. Whether it was or was not used on other 1971 models is rather moot. Although none of the other applications that I described included 1971 models, that does not mean that there were not other 1971 models that used the compressor. My list was NOT all-inclusive. Plus, I mentioned that the compressor was used on Pontiac, Buick, and Oldsmobile models without specifying which year models. I didn't bother to research that further as my resoruces in this regard are limited.

Regarding the issue of the '741'/'778' compressors and what other application that they might have, the part numbers for which those numbers are derivative may or may not have been used on the models and carlines I described in my previous post. Keep in mind that those part numbers represent an aggregation of parts which constitute an expanded ASSEMBLY as delivered to PRODUCTION. They are NOT a part number for a compressor, per se. They are the part numbers for a compressor assembly + other related parts which = an expanded assembly used in PRODUCTION as part of a complete A/C system installed on a car. The compressor assembly, itself, was not a PRODUCTION-utilized part and the part number for the compressor assembly, itself, may not appear anywhere on the unit as installed in the car. You described that there were 2 different CID compressors and that size designation applies ONLY to the compressor assembly, itself, and has absolutely NOTHING to do with the expanded assembly supplied to PRODUCTION and defined by the above-referenced part numbers. The remaining parts of the expanded assembly have no CID size designation, at all, and may be used on either size compressor.

As I mentioned in my very first post on this subject, but which I will further clarify here, I do not know if the complete compressor expanded assembly, as defined by the part numbers described above and appearing on the compressor tag, were used for any other application. I suspect that they probably were, but I do not know that. I DO KNOW, however, that the compressor assembly (the part with the "CID" size which you described) which is part of the expanded assembly, was used on MANY other cars, including mnay other model year Corvettes, many other Chevrolet car and truck models, and many other GM car lines.