6 or 8-vane water pump?

-
DartGTDan

DartGTDan

'71 Dart GT Fan
Joined
May 29, 2004
Messages
1,725
Reaction score
2,371
Location
metro-Detroit
I'm going to do some underhood work soon (double roller timing chain & gears, LD4B intake, 1406 carb, etc...) and decided to replace the water pump as well.

I know there were 6 or 8-vane water pumps available. The local parts store has the 8-vane on the shelf, but does not have, and cannot get, the 6-vane water pump.

I don't know which water pump was on the car originally. The car is 1971 Dart GT (Swinger), 318, 2-bbl, console shifted A904 automatic transmission, A/C (temporarily removed), PS, with a 3.23:1 sure-grip 8 3/4"). The car still has the A/C pulleys & brackets, I just removed the compressor and bought a single shorter belt (alt. to crank. VS alt. to crank. to compressor).

The car is a cruiser to and from ice cream parlors and local car shows. Usually surface roads only, rarely on the highway, and never ever on the track.

Will the 8-vane water pump be sufficient for my needs?
 
determined by the size of the crank pulley.
The small pulley used the 8 vane and the larger pulley used
the 6 vane..same flow.
 
8 works just fine on a daily driver 318, from idling around town or 11-12 hours of 80 on the freeway.
I wouldn't put an 8 on a car that ran high RPM's though. (like a sprint or strip car)
 
Lelo Dart said:
Why not?
Click to expand...

I feel than an 8 impeller pump could cavitate easier at higher RPM's.
AND at higher RPM's the pump won't efficiently use or need 8 vanes anyway.

Just a personal feeling about it.
 
TrailBeast,

Thanks for the input. I was hoping the 8-vane, available at my local parts store, would be the ticket. As stated usually surface streets, rarely exceeding 50 m.p.h.

ir3333,

Do you know the dimensions of the pulleys (I assume diameter in inches)?

diymirage,

I have the 1406 already, just trying to "get my ducks in a row" before I do the swap.
 
6"and 7" seem to ring a bell but i'm not sure.
a stock mopar small block water pump flows about 20% more than
ford or chev and are plenty.
 
maybe pulley size was part of the deal, but the main deal was with or without A/C. I forget which way it went, no big deal, perfectly interchangeable
 
I've been running the Milodon 8 vane pump with its anti-cav plate since year 2000 or so.As a streeter my engine never sees 7200 for more than 5 seconds at a time, and rarely more than 5000 times in one outing. Hah, kidding! Probly no more than once or twice per hour, sometimes a lot more but mostly not. How am I doin' on the wordiness scale? Yeah so I gotta say that pump does a fine job of keeping my giant-killer cool. I gotta assume the plate really works, cuz the oem 6-blader had a problem with that.With that story finished, I highly recommend the 8 vane but with a plate. Well for you, with your stated useage,you could probly skip the plate. However, since my plated pump has lasted at least 15 years so far, and for you would have lots of room for future expansion, and costs just a bit more, I would still recommend it; pully size be ignored.
 
When I had to replace the water pump on my 318 (no A/C) last year the parts store catelogs didn't indicate if a 6 vane was for A/C or vice versa. When I pulled the old water pump off mine it was an 8 vane so I ordered an 8 vane replacement. I'm not sure if there is a definitive reason why some had 6 or 8 vane water pumps?
 
Marcohotrod said:
maybe pulley size was part of the deal, but the main deal was with or without A/C. ...
Click to expand...
Several of us here figured the difference was due to the pulley size. That does map to AC or no-AC, which is why catalogs listed it that way, i.e. an easier question than "what size is your pulley?". No reason the designers wouldn't want a certain max flow-rate, either with or without AC since cost was the same.
 
You must log in or register to reply here.
-

Back
Top