Water pump to A/C car... BB

[Nacho-RT74]

There are 6 reels and 8 reels WP for BB I know one is for AC cars and the other one is for non AC cars. AC cars have smaller pulleys than non AC cars. Dunno why I think 6 reels WPs are to be matched with smaller pulleys AC assemblies and 8 reels are to be matched with bigger diameter pump non AC cars.

Am I alright?

[John_Kunkel]

Yes, the 6-vane pumps are for A/C cars that have smaller WP pulleys and run at 140% of crankshaft speed. 8-vane pumps are for non-A/C pumps that run close to crankshaft speed.

The exception is early sixties cars that ran the pump near crankshaft speed even with A/C.

[Nacho-RT74]

ok... what's reason for that ?

something wrong runing 8 vanes on smaller AC pulley cars ? Since I'm stroking the engine, I want to guarantee the best cooling with stock setup

I removed the water pump on weekend and discovered it had 8 vanes. It has been locally rebuilt in the past. I have to replace the proppeler now ( if not a complete rebuilt thought ) so I want to request to rebuilder to fit the right/best option propeller, 6 or 8

if 6 vanes is better on smaller water pum pulley, preffer that then

[John_Kunkel]

The theory goes like this; the larger impeller with 8 vanes can cavitate at higher rpm, the smaller impeller with 6 vanes is less likely to cavitate at high rpm. The reason for turning the pump faster is to increase the fan speed and provide extra cooling air flow.

An explanation of cavitation:
"Suction Cavitation occurs when the pump suction is under a low pressure/high vacuum condition where the liquid turns into a vapor at the eye of the pump impeller. This vapor is carried over to the discharge side of the pump where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure. This imploding action occurs violently and attacks the face of the impeller. An impeller that has been operating under a suction cavitation condition has large chunks of material removed from its face causing premature failure of the pump."

[Nacho-RT74]

thanks... sounds pretty much logic!

[Nacho-RT74]

is there some diff on the reels if faced to one side or the other side ?

[Nacho-RT74]

for example, note the diff on these ( beside the 8 or 6 vanes diff ), reels are faced diff

http://cgi.ebay.com/ebaymotors/New-Water-Pump-Big-Block-Mopar-Chrysler-383-400-426-440-/220844827967?pt=Motors_Car_Truck_Parts_Accessories&hash=item336b60a53f

or

http://cgi.ebay.com/ebaymotors/Mopar-Performance-P5007643AB-Aluminum-Water-Pump-JEGS-/400212392177?pt=Other_Vehicle_Parts&hash=item5d2e8478f1

against:

http://cgi.ebay.com/ebaymotors/BB-MOPAR-CHRYSLER-CHROME-WATER-PUMP-NEW-383-400-440-/140599265529?pt=Motors_Car_Truck_Parts_Accessories&hash=item20bc5e88f9

[John_Kunkel]

The bottom two examples have the correct vane orientation, either the top one has the pic flipped or it's for reverse rotation serpentine installation. 

[Nacho-RT74]

but all 6 vanes I have seen are like the top one:



look at this:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=160373539907&ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

[Nacho-RT74]

just got locally a NOS piece ( or supposelly NOS, definitelly rusted by the time not by water ) and its 6 blades but vanes orientation just like the others 6 vanes posted