A6 Compressor displacement

[Tom L.]

I've been reading the service manual in preparation to put the A/C system back into my car and found that all A6 compressors are not created equal. Seems non-corvette applications have a displacement of 12.6ci and corvette applications have a displacement of 10.6ci. With that in mind I searched the archives in hopes of finding more about them but didn't find a lot.

I have two compressors, one correct for the car with the superheat switch and incorrect pulley, and one incorrect without the switch and the correct pulley. Since they both pump when turing by hand I figured that I'd swap the pulleys and whaile at it re-seal it. So here's my questions:

While apart, is there a way to determine what the displacement of each compressor is other than measuring the stroke and bore?

In the archives there was some discussion that the larger displacement compressor results in an idling problem. I also read that re-builders don't differentiate beween the larger and smaller displacement compressor. Is anyone aware that they have the larger displacement compressor and has anyone experienced this problem?? The car in question is a '72 LS5 w/ auto.

[Domenic T.]

Re: A6 Compressor displacement

Tom,
This may help your question. All have a 1.5" bore and the stroke is the same (swash plate). The difference is in the piston. One is a flat top (high compresson), and one is dished, (low compression). The dished are in the corvette A-6 and reduce the area of each cylinder. The dish is .100 deep and 1'' in diameter.
The parts are all interchangeable and I would use the word area rather than displacement. For some reason I can't take the pic out of my file.

DOM

[Tom L.]

Re: A6 Compressor displacement

No need for the pic. I understand what you mean about the dished piston. Since you've done a buch of these for people, have you done "Flat top" compressors for corvette guys and gotten any negative feedback about the difference? Specifically idle probelms with the a/c on.

[Domenic T.]

Re: A6 Compressor displacement

Tom,
I can't see where there could be a idle problem VS. flat top or dished. I am sure the idle drop was because of the drain on the altinator and the compressor draw.

The compression was in direct respect to the ambient temp.

In answer to your question, about 2/3 compressors I do for corvetts now are flat tops and not the original dished that they came with. The standard vette pulley size is 5 3/4 with exception of the 6 3/8 for the 327 (hi rev), and some that I get are 4'' pulleys with flat tops and work just fine.
I think GM had to do the pulley & compression for the (youngens), ones that got the cars at graduation. The A-6 will hold up to abuse with any piston or pulley.

DOM

[Tom L.]

Re: A6 Compressor displacement

Good to hear that there are no problems with the different compressors, guess what I read in the archives wasn't completely accurate, it happens.

You brought up pulley size and raised a concern. The pulley I planned on putting on the compressor is a 5" pulley. I had checked with a buddy on the other coast with a very similar car, I can't just go see it, and he measured his and said it was about 5" so I felt I was good. Guess I was wrong. Aside from originality, will the 5" pulley be a problem? I don't beat on the car, it's mostly a cruiser and a big block not a high winding small block.

So, please tell me the 5 3/4" pulley is not a corvette only piece. Either way any idea where I can get one or am I hunting the net or waiting until Carlisle in hopes of being lucky?

[Domenic T.]

Re: A6 Compressor displacement

Tom,
It may be where the pulley is being measured from. I have both and will post the measurments today. The correct belt will not fit properly with the wrong pulley. You would have to use another belt that fit if your pulley is the wrong size. I am running a BB 425HP in my Chevelle with a small pulley and it's fine.

DOM

[Domenic T.]

Re: A6 Compressor displacement

Tom,
The vette pulley measures 5- 3/4'' on the outside and the passenger car meaures just over 5".
DOM

[Wayne M.]

Re: A6 Compressor displacement

....So, please tell me the 5 3/4" pulley is not a Corvette only piece. Either way any idea where I can get one or am I hunting the net or waiting until Carlisle in hopes of being lucky?

Tom -- the 5_3/4" pulley was on many Chev products; here's one I picked up at a swap meet in 2012 (almost gave me a hernia carrying it about a mile back to the car). Seller said off a '64 Belair. Double benefit as this has the early 6-hole hub on the clutch. Believe I paid $20, including the muffler and manifold. Pulley spins like a charm on its bearing. Saw another 5_3/4" dia. at same swap in 2013, but passed (and my body thanks me). 2nd pic is of a rusty NOS 5_3/4, Delco 15-216, GM # 5914745. If you're searching eBay or swaps for NOS, the Delco # is (according to their '73 catalog for '72-74 big block Corvettes) is 15-224, and the GM # is 6550750; one eBay seller says approximately 5_1/8" dia. [3rd and 4th pics]

[Tom L.]

Re: A6 Compressor displacement

Thanks for the good news Wayne, one year or corvette only parts can be a pain to find, I'm still looking for a couple. You kind of opened the door for my next question, are the clutch the same for all compressors or re the pulley and clutch and coil a set? My thouht was that the clutch and coil are the same. Thanks!

[Wayne M.]

Re: A6 Compressor displacement

Tom -- the clutch, pulley and coil are 3 separate Delco parts. Again, from my Delco A/C parts catalog, dated Jan '74; the clutch drive is Delco # 15-41, to service all years '63-74. The "coil & housing, clutch" is # 15-45, again, to service all years '63-74.

In my Corvette catalog P&A30B (the newest I have), it shows the clutch (they call it "plate -- A/C compressor clutch actuating") as # 5914719, in group 9.188. The coil (& housing) is group 9.186, part # 6550835.

The pic shows the coil & housing still installed; the clutch is lying on the table with the friction surface facing up.



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