Correct Water Pump

Discussion in 'Street/strip 400/430/455' started by '72 Skylark Custom 4bbl, Apr 30, 2019.

  1. '72 Skylark Custom 4bbl

    '72 Skylark Custom 4bbl Well-Known Member

    Good evening everyone, I know this is a common question here but I need to know the correct length water pump for my '72 Skylark Custom. I want the fan to be as close to the proper distance for max cooling.

    I'm transplanting a 455 into my 350 Lark. The closest I got was Larry's answer from 2014.

    Here's my setup:
    1973 XF block
    1235777(crank pulley)
    1235778(water pump pulley)
    1238973('72 fan shroud)
    TA 1537HP pump
    2 row 1" tube aluminum radiator

    Just looking for the definitive answer between long & short.

    Thanks,

    Kyle
     
  2. hugger

    hugger Well-Known Member

    You can only use the long pump with those pullies
     
  3. '72 Skylark Custom 4bbl

    '72 Skylark Custom 4bbl Well-Known Member

    Ok. Will this set-up give me the correct fan-shroud depth that I need?

    Thanks,

    Kyle
     
  4. copperheadgs1

    copperheadgs1 copperheadgs1

    Yes , but only if you use the 71-72 455 fan shroud and radiator rubbers from 71-72.
     
  5. copperheadgs1

    copperheadgs1 copperheadgs1

    If the shroud you list is a 350 it wouldn’t work. It would completely cover the fan. Not sure about your radiator either. Thickness needs to be same as a stock 3 core. So many guys mix and match and have nothing but trouble. Start correct and no issues. Just one item is off and you got trouble.
     
  6. copperheadgs1

    copperheadgs1 copperheadgs1

    Also find a 20” 5 blade big block fan. There are a ton out there.
     
    Smartin likes this.
  7. '72 Skylark Custom 4bbl

    '72 Skylark Custom 4bbl Well-Known Member

    Thanks.

    The shroud is for a ‘72 455 so no issues there. I’ll check the thickness of the new radiator as well.

    I will look for that fan. I have the 17” 7 blade A/C fan currently.

    Kyle
     
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member


    I don't know about that Dave. The shroud attaches to the radiator support on bottom, and to the cover on top. The rubber isolators just locate the radiator in the support. Using a thicker radiator just entails massaging them a bit. The 71-2 shroud doesn't even touch the radiator, there is a good 1/2" all the way around unlike the 70 shroud, so the shroud would be in the same position regardless of the radiator used.
     
  9. copperheadgs1

    copperheadgs1 copperheadgs1

    I thought I remember gutting out the rubbers on my 71 for a bigger radiator which brought it closer to the shroud? It’s been a while.
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Yeah, but that wouldn't change the amount the fan was in or out of the shroud. That's what Kyle is concerned about. Regardless, it should be possible to gut the rubbers out in such a way as to keep the radiator essentially in the same position (centered in the support) despite the larger tanks.
     
  11. copperheadgs1

    copperheadgs1 copperheadgs1

    The radiator cover is slotted so there is some movement possible.
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member


    Not fore and aft though?
     
  13. 87GN_70GS

    87GN_70GS Well-Known Member

    You can also source a GM 20" 7-blade from big 70's GM cars
     
  14. '72 Skylark Custom 4bbl

    '72 Skylark Custom 4bbl Well-Known Member

    Thanks for all the info fellas.

    What GM models have the 20” fan?

    Thanks,

    Kyle
     
  15. copperheadgs1

    copperheadgs1 copperheadgs1

    70 big car 455, 70-72 all 455 with AC or heavy cooling. Probably later 455 as well but appearance may be different.
     
  16. copperheadgs1

    copperheadgs1 copperheadgs1

    I will get you a picture.
     
  17. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  18. copperheadgs1

    copperheadgs1 copperheadgs1

  19. copperheadgs1

    copperheadgs1 copperheadgs1

    76FA1F45-615E-42F0-A02E-AD1C3EB01FA6.jpeg Shows the same in the assembly manual.
     
  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Thanks Dave,
    Yeah, I just used them as examples, they would work, but they are not correct. Correctness might not matter to someone on a budget. The 5 blade fans always looked weird to me due to the non uniform distance between the blades. When I bought my GS, it had a 5 blade 20" fan and 71-72 shroud on it. One of the first things Bruno pointed out to me when I met him for the first time.:)
     

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