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What's the difference between short and long water pumps?


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Does one require a different crank and alternator pullys? Is there a weight difference? Should I get the short style water pump to keep my CG back? icon_wink.gif That sort of thing. I've never been able to find a definite answer to these sorts of questions and others, like why did they make two different styles anyway?

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They (GM) made a short style to make it fit in the corvette, you would need diff. brackets and pulleys I would think. More off a pita than the regular style.

Thure

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Yes, the short pump was on all the Small Blocks until around 69. The vette had it at least in 70, probably later, like Thurem said, to make it fit.

 

Yes, the long pump a tiny bit heavier, and what, maybe 1.5" longer? I wouldn't worry about it for weight,CG reasons icon_smile.gif.

 

I went with a long pump to be able to put the CSI130 alternator in front of the block/heads on a custom mount. It also helped me fit a big Sanden 508 AC compressor in front of the header (but just barely).

 

Look around at the brackets and pulleys available and see if things like availability and where you will mount the ALT and/or AC if you use one.

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Short pumps were on all GM small block vehicles until '69. On light trucks until '72 and on Corvettes through '96. Most short pumps have 5/8 pilot, but some Corvette pumps from 68-76 have 3/4" pilot and require different pulleys than other short pumps. Yes, pulleys are different between short and long. Easies way to spot a short pump as the timing cover almost touches the back of the pump and on a long pump their is about 3/4" between the timing cover and back of pump. 84 and up pumps are reverse rotation and not exactly the same alignment of the pulley face with the crank.

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quote:

Originally posted by thurem:

More off a pita than the regular style.

Thure

 

I politely disagree. I've loved my shortie since day one....alternator fits fine, I've had it mounted three different ways now in my continual tweaks. If it helps fit an AC compressor or PS pump I could understand. Otherwise I can't see why wouldn't want that whole engine front the extra 1"+ rearward for more clearance/free room up front to your rad and fan. I have a large clear line of site across my engine bay at the front, perhaps just a personal preference. This shows the 'line of site' once you drop things down below.

P8190003.jpg

other pics

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