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Technical Radiator cap on 8ba

Discussion in 'Traditional Hot Rods' started by gearhead695456, Feb 25, 2015.

  1. gearhead695456
    Joined: Aug 2, 2008
    Posts: 319

    gearhead695456
    Member

    What type of radiator cap do you 8ba guys run? I have a Walker radiator and currently running a 16 lbs. cap. Heard both ways that you should run lower lbs and also heard higher. Thanks.
     
  2. flatheadpete
    Joined: Oct 29, 2003
    Posts: 10,121

    flatheadpete
    Member
    from Burton, MI

    I ran a 7 lb on my Walker without any issues.
     
  3. jseery
    Joined: Sep 4, 2013
    Posts: 743

    jseery
    Member
    from Wichita KS

    16 sounds high to me, but it mainly depends on the radiator. I would check with Walker and see what they say.
     
  4. gearhead695456
    Joined: Aug 2, 2008
    Posts: 319

    gearhead695456
    Member

    Honest Charlie told me Walker calls for 15 lbs. But Speedway motors said 7lbs.
     

  5. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856

    Mike51Merc
    Member

    7 lbs, deep reach.
    No need for anything stronger than that, earlier 8BAs had 3 lb caps.
     
  6. jseery
    Joined: Sep 4, 2013
    Posts: 743

    jseery
    Member
    from Wichita KS

    At that point I guess it depends on how hot you are wanting to run it. All the pressure cap is doing is upping the temperature at which the water boils. Unless it is overheating (which should be address with other than a higher pressure cap) why run a high pressure cap?
     
  7. NMCarNut
    Joined: Nov 28, 2009
    Posts: 630

    NMCarNut
    ALLIANCE MEMBER

    Unless you have a serious cooling problem there is no reason for you to run such a high pressure cap at sea level. I live at 8000 ft. altitude and have no boiling problems with a 7 lb. cap on my blown 8BA. For what it is worth water up here boils right at 198 degrees and with the 7 lb. cap the boiling point is raised to about 222 degrees which is comfortable margin in my case.

    In your case a 16 lb. system would give you a boiling point of about 250 degrees if it ever built to a pressure that high.
     
  8. Another consideration for the flathead is water leaking past the shaft seals if the pressure is too high. original fh's weren't pressurized.
     
  9. Gene Boul
    Joined: Feb 9, 2006
    Posts: 805

    Gene Boul

    I run a 4 # cap on my 8BA and AB motors, stock radiators.
     
  10. 42merc
    Joined: Dec 19, 2010
    Posts: 753

    42merc
    Member

    Of greater concern is the heater (if equipped).
    The Walker will handle 16#, the water pumps probably have been replaced with good aftermarket items, so they will do.
    If you are using an original heater, I would limit the pressure to 7#.
     
  11. 56shoebox
    Joined: Sep 14, 2011
    Posts: 1,106

    56shoebox

    I spoke to Walker about the exact topic recently. Their tech support told me to go no higher than 7lb with a flathead. The radiator will take the 16lb their specs call for but the motor may not.
     
  12. gearhead695456
    Joined: Aug 2, 2008
    Posts: 319

    gearhead695456
    Member

    Good info here, i do have new pumps, no heater, although will most likely swap it out for 7lbs cap. Thanks.
     
  13. Thaplumbr
    Joined: May 7, 2012
    Posts: 119

    Thaplumbr
    Member

    I run a 4 lb cap on mine and have for almost 3 years now.
     
  14. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,750

    V8 Bob
    ALLIANCE MEMBER

    JFYI, Ford used a 7 lb cap for automatic transmission equipped ('51) cars, while std. trans 8BA cars kept the 4 lb cap, according to the "green" book.
     
    Last edited: Feb 26, 2015
  15. 19Fordy
    Joined: May 17, 2003
    Posts: 7,104

    19Fordy
    Member

    On my 8BA flatty I have a Walker Cobra radiator with a 10 lb. cap I bought from Walker. Being doing that since 1999. No problems. But, make sure your hoses are double clamped.
     
  16. walter
    Joined: Nov 4, 2007
    Posts: 622

    walter
    Member

    4 lbs No need for more!
     

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