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Correct water pump

pjm8047

pjm8047

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quick question. I’m going to replace my original 71 383 none ac water pump and I’ve seen a lot of water pumps online says fits big block Mopar’s but some have 8 blades and others have 6 blades. I haven’t removed it yet so I’m not sure what I needed.
 
I've been useing the eight blade and no cooling problems at all. Pully size can make some difference, pump housings have minor differences, ect. Some pumps have slightly different blade designs also.

If I were you, and you haven't had any cooling problems, I would replace it with exactly what you have now.

20170520_144948.jpg
 
Just checked service manual the difference is non ac has 8 blades and ac 6. Last line in pic.

732D7297-B9C0-40DE-9CEC-4E9CF43E0593.jpeg
 
6 blade for ac since a smaller pulley is used, 8 for big pully. 8 on ac might give high speed cavitation
 
I had an 8 blade hv summit pump and it hardly flows at idle after the stat opens but flows well at higher rpms. I just changed it to a milodon hv pump with 6 blades which are longer. The flow at idle is much better.

20190718_175624.jpg 20190718_174127.jpg
 
Ceedawg said:
6 blade for ac since a smaller pulley is used, 8 for big pully. 8 on ac might give high speed cavitation
Click to expand...

Do you know the diameter for each pulley? They were matched per application. Since I already have the pulley I'm going to let that dictate how many blades I go with. Thanks
 
Went threw this over the summer. There is a post on DC.com . The 8 is supposed to be for non ac and 6 for AC.

Majority of the aftermarket are 6 blade but fin shape is different and they have a plate welded to the back of the fins that none of the OEM have. I do belive this supposed to help increase flow. One thing I noticed is that I would say 80% of after market are identical with different names on them . I went Proform aluminum hI flow from summit advertised as "mopar authentic."

Another member posted up one that he got off rockauto for 30 bucks or something like that . It is IDENTICAL to the one I have and paid almsost 100 dollars more . If I had to do it again I would get one from my local napa that has 8 blades for 60 bucks .
 
I took a $32 GMB (Japan) pump and welded the anti-cavitation plate on it. I also have a Flowkooler and it's the identical pump with their impeller on it. A little OT but I agree with KID if he has no other issues I would stick with what he's got.

G_F_Front.jpg G_F_impeller.jpg
 
Ceedawg said:
6 blade for ac since a smaller pulley is used, 8 for big pully. 8 on ac might give high speed cavitation
Click to expand...

True, the 6 blade impeller used with the A/C application uses a smaller drive sheave, but the purpose was to increase circulated coolant, more GPMs at a higher velocity to improve heat transfer characteristics.
IMO....cavitation will not be a problem, as the entire system is under pressure, as the system pressure will negate the pump's suction pressure losses. Its the pump's suction pressure losses causes cavitation in the first place. In addition, the circulation (and pumping losses) is influenced by the composition of the coolant being pumped. Most, if not all, commercially available coolant compounds have a "anti-foam" additive to inhibit cavitation.
BOB RENTON
 
I took this picture off another forum, the 6 blade looks like it runs the opposite way. Is that true?

2B2C456C-E83E-42EE-822E-CA3798F30BE2.jpeg
1BE2BD9A-9003-4AB6-9027-888030356DB7.jpeg
 
I have a 440 in a 74 Barracuda with a 22" radiator (non-AC car). My concern is that with less surface area, faster transit through the core may not be a good thing. Mopar was using different pulleys and pumps for a reason. If the 8 blade and larger pulley was their answer on a non-AC car, that is what I'll stick with. The NAPA unit looks pretty good to me.
 
Montclaire said:
I have a 440 in a 74 Barracuda with a 22" radiator (non-AC car). My concern is that with less surface area, faster transit through the core may not be a good thing. Mopar was using different pulleys and pumps for a reason. If the 8 blade and larger pulley was their answer on a non-AC car, that is what I'll stick with. The NAPA unit looks pretty good to me.
Click to expand...

Incorrect assumption.... Thermodynamics states that the faster the heat transfer media moves (gpm and velocity) the more heat is transferred. Every one assumes the heat is transferred in the radiator but the other half of the equation is the heat source....the engine. There is more surface area in the engine to absorb heat than in the radiator to dissipate the heat generated, therefore the faster the exchange takes place, the more heat is transferred. Ideally, if the surface areas are equal, the heat absorbed and subsequently released could be equalized, but they are not, so the velocity and guantity of the heat exchange media must be increased to maximize the heat transfer rate...... Investigate the equation: Q (heat) = M (mass or mass flow) x Cp (specific heat [ability to absorb and release heat in a given amount of time ] of the heat transfer fluid) x delta T (temperature differences) for a better understanding. If your application is running "hot" consider up sizing the radiator to increase the surface area. Just my opinion of course.
BOB RENTON
 
Last edited:
Montclaire said:
I already graduated, thanks.
Click to expand...
What school did you graduate from ..... PSU...or one of the branch campuses ....or perhaps Penn, or Drexel or Univ of Pgh or ???. What was your major??? Mechanical Engineering or ?? I did PSU + Pitt..... "Inquiring minds want to know".....
BOB RENTON
 
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