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A6 Pulley Diameter 5" versus 5 5/8"

y2k600f4 on Wed September 10, 2008 12:06 PM User is offline

Year: 1980
Make: Camaro

Seems like the stock pulley diameter was 5 5/8" but most rebuilds are 5". Is there any issues with changing to the 5" pulley and just changing the belt to accommodate the reduced pulley diameter ?

TRB on Wed September 10, 2008 3:03 PM User is offlineView users profile

It will spin a little faster and need a shorter belt. In my opinion it's not really going to hurt much but GMTech may have some data to suggest otherwise.


When considering your next auto A/C purchase, please consider the site that supports you:

Edited: Wed September 10, 2008 at 3:03 PM by TRB

y2k600f4 on Wed September 10, 2008 3:58 PM User is offline

Thanks Tim....didn't think it was a big deal.

Just wondered why some models had it stock with different size pulleys and rebuilts only had the one diameter you said probably no big deal. Seems to be an increase of maybe ~300-500 RPM of the compressor during normal operating engine RPMs.

Edited: Wed September 10, 2008 at 5:27 PM by y2k600f4

retrofit on Wed September 10, 2008 4:36 PM User is offline

It appears that the larger pulley is history. The old GM 6580040 ACDelco 15-4627 is no longer listed. The smaller one, GM 6580140 ACDelco 15-4619 is now listed for applications that used to call for the larger one.

GM Tech on Thu September 11, 2008 9:27 AM User is offline

Go with the flow- and always note that your belt is now not stock.

Had a Cadillac last week that had a 5 groove belt on a 6 groove pulley system- I thought that was odd-- but it needed a compressor- the old 4-Seizens pump was knocking bad-- I told the owner I would put the right belt on it at the same time-- I don't look up part numbers when replacing compressors- I typically take another good "gut-pump" and build a unit for an application- in this case, I had a H-6 from a truck application- brand new- I always use the old pump as a pattern-(in this case a 4 Seizens rebuild was my pattern)- so I rotate the new front head 120 degrees, so the ears will mount, drill out the threaded holes so the bolts will slip[ through, I put on a new same exact size pulley- and mount it to the car- which in itself is a big PITA- Now I put the new 6 groove belt on- and it is too short-- whoa Nelly- what went wrong? I notice the comnpressor pulley is just a tad too big- but I'm not going to change it now that it is mounted-- I compare the old 5 groove belt to the 6 groove new belt- the 5 groover is a tad longer-- so this expalins it- the mechanic before me had the wrong pulley or 4 Seizens part as well-- so in his reluctance to change this PITA to change pump- he opted to get a new longer belt-- but it does not come longer in a 6 groove application- only a 5 groover-- so now, I've learned not to trust what I pull off- and to be suspicious. So what did I do? I hate to say it- but I was able to roll the belt on the P/S pump pulley- by cranking the engine over- the tensioner is at full stroke- but hey- the next guy to change this belt will have to cut it off- hopefully it is their regular mechanic who started this mess...

I would have "made it right" if it would not have been at midnight- And I did have a good chuckle- thinking- this guy gets what he deserves- That pump can take up to an hour to pull off and put on- due to the tightness of attaching the manifold block ....and rolling the belt on is an old mechanic's trick, that he may not have know to do...the end result was adequate, but not too terrible much tension on the belt.....I'll only ever see the car again, if the a/c has problems....

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

mhamilton on Thu September 11, 2008 4:45 PM User is offlineView users profile

The difference in pulley size was for engine load/economy reasons. On my '80 Malibu V6, the stock A6 uses the 3.75" pulley, but the replacement compressor had the smaller 5". The difference in load was apparent with the low power engine. Mathematically you're only talking about 20%. But, I asked Tim and he was able to get me the larger size pulley/bearing assembly.

Less engine load, less feel of clutch cycling, and I don't have to keep track of a non-stock belt. No noticeable reduction in cooling, either.

Edited: Thu September 11, 2008 at 4:47 PM by mhamilton

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