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Nomads 55-57,69Z28-RS,72ElCamino, Corvette(5)
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Discussion Starter · #1 ·
This began in another thread, but rather than sidetrack MMSALT's thread, I started a new thread with my questions here.. :)

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bamanomad, I think you're thinking of the other Holley accessory drive that's been on the market for some time. This one has to use unique (smaller) driven components.
You are right Rick... When I searched on the term he used 'holley mid mount accessory brackets' I was shown PN 20-131 (which might be an older system), but it got my attention as it was 'on sale' and it supposedly utilizes stock GM alternator, compressor, and PS pump/reservoir.

I have a 2001 Z28 LS engine which has brackets which place the alternator too low for my chassis, but I don't want to spend $2-3000 for a complete new custom accessories drive, so this 20-131 looks attractive to me.

Has anyone here used the 20-131 that can pass along some comments both PRO and CON re use of this system and use of the factory accessories with these brackets??
 

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The 20-131 kit has an a/c bracket made for a GM R4 compressor which goes on the top passenger side of the engine. The bracket for the alternator and p/s pump is similar to the stock LS Corvette accessory drive.

They have another kit that uses a Sanden compressor, either the large one (508) or the small one (forget the number).

I started out to use the Chevy Performance setup for the alternator and p/s, along with the Holley a/c bracket for the Sanden. This was about a year ago and that setup was on national backorder. I ended cancelling the order and buying the Holley bracket. I think it's a good piece.

The nice thing about the Holley brackets is that with the proper installation bolts and spacers, they can be used with any LS balancer and water pump. Holley sells the rotating components, but they also state in their instructions what components you can use if you want to source them yourself. Summit also sells kits with the Holley brackets and Summit sourced rotating components.

There's been several previous threads about this setup, no bad reviews but some details you may want to know, so check them out.

As for the R4 compressor, unless you just love them or have a new or little used one on hand, I'd suggest the Sanden compressor. I think it's a better value, and it's a proven product.
 

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Nomads 55-57,69Z28-RS,72ElCamino, Corvette(5)
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Discussion Starter · #3 ·
Thanks for your comments Rick!~ :)

I'm far from a 'compressor expert', but if the R4 is the standard compressor used in GM vehicles, I've had a half dozen or so new GM vehicles (trucks mostly) over the past 20 yrs or so, and put most of them thru 100K miles or 10 yrs, and never had to even recharge one of their air conditioners. Two 90 model Corvettes I have went 15 yrs or so before needing charge, so based on that.. if those were R4 compressors, their reliability and sealing seem to be great...

So I'm still leaning towards buying these brackets and using my 'used' Gm components, although I'm not sure the Camaro Z28 PS pump/reservoir combo will work with that 20-131 kit...? I'll call Holley when they open back up.
 

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1956 chevy 210 del rey sedan
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go the sanden route. the adapter fittings that will connect aftermarket a/c system to r4 compressors are a POS and have to use an oddball sealing washer setup. avoid all that crap and use the sanden compressor, in the end it cost about the same and looks a million times better and on top of that you just thread the a/c hoses directly on them.
 

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Discussion Starter · #6 ·
Thanks Jake; and I'm aware of the 'installation kit' issues for the various pulley spacings... and my 2001 LS1 from the Z28 does need the 21-2.. :)

Can anyone itemize the pros / cons of the Sanden 7 versus the 508??
 

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Thanks Jake; and I'm aware of the 'installation kit' issues for the various pulley spacings... and my 2001 LS1 from the Z28 does need the 21-2.. :)

Can anyone itemize the pros / cons of the Sanden 7 versus the 508??
The 508 is larger displacement not really needed. Be careful on Sandens.
http://www.rparts.com/adnl-info/conversion_guide.htm


Most are cheap Chinese copies if its $200 its not a real Sanden. That said I haven't had an issue with the fake ones but have seen one fail the front blew off on buddies truck.
 

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the Sanden 7 is a smaller size compressor and typically runs more than the 508, both cost wise and functionally. all your typical aftermarket systems are designed around the Sanden 508 so I would stick with that. also due to the smaller size and the fact that it works harder/ runs longer the Sanden 7 doesn't live as long as the 508.
 

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the Sanden 7 is a smaller size compressor and typically runs more than the 508, both cost wise and functionally. all your typical aftermarket systems are designed around the Sanden 508 so I would stick with that. also due to the smaller size and the fact that it works harder/ runs longer the Sanden 7 doesn't live as long as the 508.
I guess I am thinking of the 708 not the 508.
 

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I guess I am thinking of the 708 not the 508.
Correct the 708 is a huge one yet it still has less capacity than the old gm axial compressors I am using the 708 on my 71 chevy and it works good enough to cycle on and off a bit more than I would prefer but the air is cold so its all good.
 

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The 508 has more displacement and a larger case. It is the Sanden compressor that's been around for years, and it's what VA uses for most of their kits (they do offer the small compressor too).

The 700 series compressor Holley offers has a smaller pulley to make up for the displacement. Due to the higher rpm and more revs/mile they will not last as long. I suppose some may think they look a little better. Thing is, the Holley bracket can use either one, they are interchangeable for this application. It has a higher rpm capability compared to a 508, but because the pulley is smaller, engine rpm capability is the same with either one.

There is a huge Sanden compressor, not usually used in the hot rod world; I don't think that it (whatever the number is) will be compatible with the bracket.

I've had good experience with an R4, but when they go, they go in a big way.
 

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Correct the 708 is a huge one yet it still has less capacity than the old gm axial compressors I am using the 708 on my 71 chevy and it works good enough to cycle on and off a bit more than I would prefer but the air is cold so its all good.
I have the 708 in my truck as its large crew cab. It works great so far. Doesn't cycle to much but never really paid attention. I know I do have to adjust temp warmer once truck is cooled down.
 

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The 508 has more displacement and a larger case. It is the Sanden compressor that's been around for years, and it's what VA uses for most of their kits (they do offer the small compressor too).

The 700 series compressor Holley offers has a smaller pulley to make up for the displacement. Due to the higher rpm and more revs/mile they will not last as long. I suppose some may think they look a little better. Thing is, the Holley bracket can use either one, they are interchangeable for this application. It has a higher rpm capability compared to a 508, but because the pulley is smaller, engine rpm capability is the same with either one.

There is a huge Sanden compressor, not usually used in the hot rod world; I don't think that it (whatever the number is) will be compatible with the bracket.

I've had good experience with an R4, but when they go, they go in a big way.
actually the Sanden 708 fits the standard holley ls A?C bracket and works well. that is what is on my 71 chevy with a ls1
 

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The 508 has more displacement and a larger case. It is the Sanden compressor that's been around for years, and it's what VA uses for most of their kits (they do offer the small compressor too).

The 700 series compressor Holley offers has a smaller pulley to make up for the displacement. Due to the higher rpm and more revs/mile they will not last as long. I suppose some may think they look a little better. Thing is, the Holley bracket can use either one, they are interchangeable for this application. It has a higher rpm capability compared to a 508, but because the pulley is smaller, engine rpm capability is the same with either one.

There is a huge Sanden compressor, not usually used in the hot rod world; I don't think that it (whatever the number is) will be compatible with the bracket.

I've had good experience with an R4, but when they go, they go in a big way.
actually the Sanden 708 fits the standard holley ls A/C bracket and works well. that is what is on my 71 chevy with a ls1
 

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Just to clarify the Sanden compressors usually used on this stuff.

SD7B10 - 100cc/rev 9000 rpm according to Vintage Air, 6000 by other sources

SD5H14 - also known as SD508 - 138cc/rev - this is the most common Sanden compressor

SD7H15 - also known as SD709 - 156cc/rev - this is the big one - I didn't verify that it mounts the same as a 508 but it probably does based on what hotrodg726 says.

Holley sells the SD7B10 and SD5H14 for their LS accessory drives.

The "5" and "7" designate 5 or 7 pistons.
 

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In oem application GM turns off the A/C compressor at WOT so the stock units never see rpms above 6k. Why on earth would you spin one to 9k? Is thay pulley speed I assume?

The mounts for the 709 is same as sanden as I have one it fits standard sanden bracket. So feet spacing is the same.
 

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RPM is compressor rpm not engine.

The Holley a/c kit has a separate warning sheet that cautions you to install a switch that shuts off the compressor power at 4000 engine rpm. I posted about this a few months ago. Their solution to this is a switch/hardware that costs $150 or so. Not acceptable. Found one that's more like $50. Still don't want to pay that. I'll probably use a Dakota Digital instrument panel, and use the shift light function to trigger a relay, more like it. Of course, you can just reach over and cut off the a/c if you're going to wind the engine past 4000. But crap, I occasionally turn the 5.3 in my truck to 5000 rpm without ever thinking about it.

The three compressors I listed are the 3 Sanden compressors that Vintage Air sells. Almost everyone uses one of them.
 

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Bo, what controls shutting it off at WOT?
the engine ecu is tied into the A/c system and will shut off the compressor at WOT
 
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