B block water pump confusion..help!

[keeper of the plains]

I have a 68 b body with factory air. after doin a radiator flush i soon sprang a leak from water pump area. My service manual mentions that a/c cars have a diferent pump than non a/c cars..i read online that a/c cars are 6 vein and non a/c is 8 vein with the a/c version is 30% overdriven. the pump i pulled off was a8 vein?oreilys only had 8 vein listed for my car? was wrong pump on car when i got it? It had overheating issues to start with. could this b some of it?

 

[65belv]

Are you suggesting that the A/C water pump has fewer veins but has a smaller pulley so it is overdriven 30% ? I had a chance to view a collection while travelling and took photos of several engines and I noticed that only one big block had a smaller pulley than the others. I'll check the photos for details.

 

[keeper of the plains]

yes. I found two different part#s for waterp pumps..ac and non.and the a/c does have a smaller pulley.but i found one forum conversation that someone claimed the 8 vein was for a/c,vice versa

 

[keeper of the plains]

a post claims that the 8 vein on the a/c(overdriven pulley) would move the coolant too quickly,thusv not alowing the system to properly cool. cavitate?

 

[Cranky]

a post claims that the 8 vein on the a/c(overdriven pulley) would move the coolant too quickly,thusv not alowing the system to properly cool. cavitate?

I've read the same thing years ago. And yes, you can turn a pump too fast and cause too high of flow and cavitation. There's a lot of info on the net on the subject of centrifugal pump dynamics and that's what you have on your car...a simple centrifugal pump.

 

[keeper of the plains]

it seems the 6 vein makes more cense?

 

[keeper of the plains]

is it possible i have the wrong pulley? i have a non ac engine in garage...i will investigate

 

[keeper of the plains]

the pulley is smaller by an inch or so. 5 inches and 6 for non a/c. o'rielys, autozone, and advanced do not have a six vein pump. the screen asks ac or non, but both pump numbers are the same? lol

 

[keeper of the plains]

In case anyone was interested i found in service manual that mixmatching pumps is illadvised and will cause issues..a/c equiped 383 have a 3.67'' 6 vein pump and non a/c use the 4.38'' 8 vein pump. now i just need to find one

 

[chignikred]

big blk pump VANES

Here is a photo from my milk crates collection. fronts are large, rears are a/c small. Two style of impellers.

Note:
Vanes are blades on impeller
Veins carry blood
Vain is self pride that is unwarranted

 

[Meep-Meep]

I have run the 6 blade (as pictured above at the left rear) with a STD non A/C pulley and never had issues. It's claimed to be a high RPM HP increase to run an A/C pump on a non A/C car. I have even removed every other blade on the large 8 blade impeller and had no issues with cooling. However, if your pump is cavatating I believe that will lead to over heating because the flow is interrupted.

 

[keeper of the plains]

The replacement pump i bought from Advanced Auto is a six blade, but blades are larger than stock a/c pump. the orientation of blades are the other direction than normal..doesnt look like it will effect pump efficiency- blades are still flat, tabs are just bent other direction? It is a new pump, and part # is same for a/c- non a/c? thing the GMP brand pump would work ok?

 

[keeper of the plains]

Sorry, that pic is a joke..LOL