1970 AC compressors

[D S.]

What is (or are) the difference(s) between the 1970 big block 5910740 and small block 5910741 A-6 compressors?

Thanks,
Scott Sims
Texas Chapter

[Edward J.]

Re: 1970 AC compressors

Scott, Paragon corvette list the same numbers for big or small block a/c compressors. I would say they should be the same. maybe the pulley sizes maybe the difference between big and small blocks. or clock position of the wires coming from the top or side, I know that my 72 sm/blk. a/c car is clocked different from 70-71 car.And note that 72 cars have a extra switch on rear of compressor.

[D S.]

Re: 1970 AC compressors

The 1970-1972 JG states that the 5910740 is for 1970-1971 454s and 1972 changed to 5910797 for 454s but does not go into detail about differences from the small block compressors. Based on that vague description I would assume I could take any 1970 dated A-6 compressor and slap a 5910740 green sticker on it for a big block application and it would pass NCRS judging for a big block compressor.
Looking at photos of Juliet Page's small block compressor (from her 1970 Corvette Registry Photographic Library) I can see no visible differences between hers and my big block compressor. http://www.1970corvetteregistry.org/acdetails.html

[Jack H.]

Re: 1970 AC compressors

Not if the judge knows his stuff (slap a BB A-6 label on a SB A-6 compressor)...

Check your copy of the Parts & Accessory Manual and you'll find there were different drive pulleys for SB and BB compressors. The PN on the A-6 label denotes a full compressor system (compressor with pulley assembled, ready to drop-in).

If my recollection is correct, the BB pulley will have a greater diameter by something like 1/8-inch. Doesn't sound like much, but walking down the line of side by side cars on the judging field, the difference JUMPS at you...

Then, of course, there's the difference in 'plumbing' with the BB manifold having a shorter pipeline from the muffler to the mounting block vs. the SB. And, '72 compressors incorporated the superheat switch feature that '70-71 cars lacked which makes their wiring harness and rear plate different...

[Bill C.]

Re: 1970 AC compressors

The BB pulley is a smaller diameter than the SB pulley.

[D S.]

Re: 1970 AC compressors

Thanks, Jack!