Water Pump Question

Small Block Mopar Engine

  1. dICKj

    dICKj Well-Known Member

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    I have read warnings not to try to use a non-AC water pump on a 318 motor with AC, and not to use the AC water pump on a 318 without AC. What is the difference. I am removing factory AC from my 1974 Duster. Is it a problem with all the brackets for the AC, or is it a problem with belt alignment? Or something else entirely? Thanks, DJ
     
  2. Jadaharabi

    Jadaharabi FABO Gold Member FABO Gold Member

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    I think some people has it in their head that the air conditioning water pump moves water faster than a non air conditioning or moves more volume than a non air conditioning car or vice versa.
    Remove your AC put some belt on it and run it. If it does overheat then switch to the non air conditioning water pump. But I don't think you'll have a problem
     
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    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      Don't pull a bunch of brackets off and then screw those long bolts in there and punch a hole in one of your cylinders. Namely number one driver side front.
       
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      • Dana67Dart

        Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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        If you look in the parts books you might find that the pulleys for AC cars different diameters than for non AC cars, so impeller differences might be altered by the pulleys.

        IMHO
        Check the parts book and abtain the crrect parts to change from one to the other.
        Too fast a water pump MIGHT cause cavatation. Too slow might not move enough volume
         
      • Biff

        Biff Cheep not easy

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        Does one impeller turn right and the other left ?
         
      • Jadaharabi

        Jadaharabi FABO Gold Member FABO Gold Member

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        The LA turns the opposite direction of the Magnum.
         
      • Biff

        Biff Cheep not easy

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        Thanx but the question posted was a/c water pump vrs non a/c is there a difference between them ?
         
      • Jadaharabi

        Jadaharabi FABO Gold Member FABO Gold Member

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        .
        No that was not the question.
        .
        This was the question you ask.


        The answer is LAs turn one way and Magnum the other way.
         
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        • RedFish

          RedFish Well-Known Member

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          Impeller design is the only difference in them. If you search google images you'll find at least 4 different impellers in the same pump castings.
           
        • 12many

          12many Well-Known Member

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          I don’t pay attention to whether the listing says A/C or non-A/C. There are 6 vane and 8 vane impellers. I look at the description and pictures to verify it has 8 vanes and the plate. I always run those in any setup as I want that coolant to flow, which it does. Don’t nobody start that nonsense about the coolant not having enough time to draw out the heat if it moves faster etc. That’s a bunch of BS.
           
          Last edited: Jun 7, 2021
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          • cudamark

            cudamark FABO Gold Member FABO Gold Member

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            That's true, it has nothing to do with the water pump.....that has to do with removing the thermostat. The impeller question (6 or 8 blades) has to do with water flow volume. Most times using an 8 blade impeller pump won't cause a problem, but, not always. I've seen A/C engines with the 8 blade impeller pump have cavitation/foaming problems. I haven't had or heard of a problem going the other way (6 Blade on a non-A/C engine) but, that may just be that there was enough flow and a large enough cooling capacity to mask that problem. From the factory, non-A/C cars used an 8 blade impeller pump, and the A/C cars used a 6 blade one. Opposite of what you would think, right? Well, the reason is that they turned the two pumps at different speeds. Non-A/C cars had a larger diameter water pump pulley than an A/C car, so, it spun slower than an A/C pump. The slower spinning pump needed the extra impeller blades to have the same flow as an A/C pump with only 6 blade, but, was spinning faster. With all sorts of pulley and pump combinations, some (most) will work fine.....some won't. Add various radiator sizes and capacities along with different thermostats, and you have almost endless combinations.....not to mention weather operating temps and conditions.
             
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            • Jadaharabi

              Jadaharabi FABO Gold Member FABO Gold Member

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              .
              Where do you find the pumps with the plate? Part number?
               
            • 12many

              12many Well-Known Member

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              I just use a Gates 43026P anytime I need a pump

              DB9E5EA6-AAFD-4D97-91C7-0478D8A04C7F.png
               
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              • Mike69cuda

                Mike69cuda 66 is the new 17 FABO Gold Member

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                I bought a flowkooler, it has 16 blades I think. I am not sure how much difference it made, as I changed a bunch of stuff. However the car stays cool now.
                 
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                • Nat

                  Nat Well-Known Member

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                  i'm using a milidon high flow from summit didn't cost much more than a regular pump keeps my car cool
                   
                • Krooser

                  Krooser Building Chinese Free Engines since 1959...

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                  IMG_20210608_082445974.jpg IMG_20210608_082440552.jpg IMG_20210608_082431681.jpg IMG_20210608_082421093.jpg CVF makes a nice high efficiency pump....about $60 on ebay. It IS Chineseum but very nice...
                   
                  Last edited: Jun 8, 2021
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