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crank\balancer shaft pulley sizes

bp71k5

bp71k5

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Knoxville, TN 37922
So I'm looking at some new pulleys for a new motor and some list for use with a long water pump and a short one. From everything I can find, the 71 k5 with a 5.7 350 came with a short pump.

The problem is when I'm looking at pulley's they list 55-68 as having short pumps and 69-85 as all having long pumps. So somewhere the information is not right. Can anyone school me? Does the long\short pump really make a difference on what size the pulley is?

I'm planning on adding a factory AC pump so I believe I need a 3 groove pulley on the crank balancer. Is it possible GM used the long water pump on AC trucks and the short on the non-AC?
 
You need to match whatever waterpump you install. If yours is short then you need pulleys for a short pump and vice versa. They are not interchangeable
 
Corvettes and trucks kept short longer than the cars .

Trucks went long on smallblocks in 73 , vettes kept short after that due to engine compartment packaging .
 
So one more question. I don't see any swp crank pulley's with 3 grooves. How were the trucks setup with AC with only two grooves in the crank pulley? I've seen an extra single groove pulley that looked like you could add to the double groove on the crank to run the AC compressor. Is that what they did?
 
3 groove is on newer rigs like my 83 . If you went long water pump and brackets from a truck with alt on pass side and a/c on drivers side , a/c is driven off of crank/fan , and alternator is driven off of crank/fan ( sometimes with a.i.r its on that same one , longer belt ) , and p/s is seperate off the 3rd ( rear ) crank spot .

I don't know if your compressor is an A6 or R4 , but both have come on the drivers side in various vehicles .
 
The pre 72 trucks appear to have the alt on the drivers side and the AC on the passenger. This makes it tougher to find bracket setups. I don't actually have a compressor yet, but want to make sure installing it is easy when I do.

I'm going to stick with the short pump since I'm looking at moving the engine forward a bit and the electric fan clearance could be an issue.

My old two groove crank pulley was actually two pieces. One was just a flat pulley and the other had a kinda dish in it so they fit together nice. I figured pulleys would be an easy thing to figure out. :doah:
 
Since you have no compressor anyway , convert to the newer smaller compressor , either a new R4 ( remans all blow up ) or a Sanden compressor , and just have the hoses made up for reaching .

And convert to the newer setup(s) on the alternator too .

Your rig isn't going to be truly factory correct with all that upgraded wheeling gear anyway :wink1:
 
If your truck did not come with factory air, you might want to consider a used or aftermarket AC setup. Many suburbans had aftermarket AC systems installed at the dealer or independent installer. Many of these units fit above the heating system and behind the glove box. They use four ducts at the same locations as the factory system. Most of the systems I came accross used Sanden compressors. Whatever compressor you use make sure it is dessigned for R 134 refrigerant or it will blow its shaft seal.
 
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