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Is there a internal differance between a reverse rotation water pump, and a normal rotation pump for a SBC???

does it REALLy make any differance which way the thing turns???

the way I remember it, is the impeller has straight finns, and so could turn either way and get the same flow....

anyone actually KNOW???

:surprised :WTF :cheers: :huh:
 

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The vanes on the impeller are curved. That's where the direction of rotation comes in. A reverse (serpentine belt) pump will take a regular pulley, but it'll overheat. Same for the other way.

:cheers:
 

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Discussion Starter #3
The vanes on the impeller are curved. That's where the direction of rotation comes in. A reverse (serpentine belt) pump will take a regular pulley, but it'll overheat. Same for the other way.

:cheers:
Son of a bitch, you sure on that?? I flat don't remember....they may explain a problem I have on a SBC engine...drive me crazy, WTF...:smack :WTF :WTF :cheers:
 

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Sorry to be the bearer of bad news, but YES, I'm sure. Back when they (GM) first started the serpentine belt thing, the rebuilders didn't have but the one part number for standard rotation. And externally, they LOOK the same. There were lots of pumps installed and had overheating problems from the get go. Then they found out why. Impeller is cut for the direction of rotation.
 

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Sorry to be the bearer of bad news, but YES, I'm sure. Back when they (GM) first started the serpentine belt thing, the rebuilders didn't have but the one part number for standard rotation. And externally, they LOOK the same. There were lots of pumps installed and had overheating problems from the get go. Then they found out why. Impeller is cut for the direction of rotation.
OK, so for a normal rotation engine, pump, with V belt drive.... when taking the back cover off the pump,looking at the impeller, which way do the vanes twist.....??
 

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GM uses semi open impellers on their good pumps and indeed like Tim says, they are directionally curved. However the later GM pumps (smoggers) and many of the cheap aftermarket ones have a stamped steel open style impeller and they are not curved but straight, however the vanes are not radially placed but offset (just like on an alternator) like this




Easy to spot the rotation on that one, the vanes are placed in front of the
rotation direction and it's a reg. direction pump.
 
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