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Major Bummer Overheating BBC

Discussion in 'The Hokey Ass Message Board' started by billbrown, Jun 6, 2011.

  1. billbrown
    Joined: Dec 24, 2007
    Posts: 595

    billbrown
    BANNED

    ill make this quick. 37 chevy truck. New Radiator built by Superior Radiator. Thermostat/restrictor plate. Big Block Chevy with dual quads and spot on timing. Really good electric fan that is spinning in the right direction with a shroud. Stick trans. no extra coolers Gauge works properly. carbs are a little fat, but not fouling plugs.

    The million dollar question: Why does my junk ass hot rod get into the 215 to 220 range at normal driving speeds. Hangs out around 160-170 all day at idle. Any ideas guys? Thanks.:mad:
     
  2. jamn47
    Joined: Jan 3, 2011
    Posts: 135

    jamn47
    Member

    That restrictor at hwy speed may be slowing the coolant flow down too much, causing excessive heat. Just a thought. You water pump is spinning faster but can't push the coolant through quick enough. At idle the restrictor would probably be fine.
     
  3. A Friend of mine just ran into this problem he had a standard water pump with a serpentine pulley system those water pumps spin opposite to a regular pump. He was boiling over with a 1 ton duelly . If not that what about an air lock in the head another friends race car had to open the pedcocks a bit and draw water through the engine , generally it would let a big air bubble go doing this. Then we would close the pedcocks and slowly fill the rest of the way. Hope this helps , Rob.
     
  4. davidbistolas
    Joined: May 21, 2010
    Posts: 962

    davidbistolas
    Member


  5. spiderdeville
    Joined: Jun 30, 2007
    Posts: 1,134

    spiderdeville
    Member
    from BOGOTA,NJ

    the flow of electric fans pales of a good clutch fan , try running without a hood
    see if airflow is the problem , you shouldn't need a fan at highway speeds
    new chevy trucks operate at 210 degrees
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 49,263

    squirrel
    Member

    pictures might help. Could be lots of things....I would run a thermostat, and a mechanical fan if at all possible. I expect the radiator is not real big, and it's a tight squeeze putting a big block in an early truck.

    by "spot on" what do you mean? does it get at least 36 degrees advance by 2000 rpm?

    and as mentioned, 220 is not really a problem, if it gets to 230 it's a problem, or if the coolant boils
     
  7. Nearly every time you have an overheating problem it has to do with airflow.

    You mention having an electric fan and shroud. At highway speeds, more air needs to get through the radiator than the shroud and fan will allow. You will notice on most all OEM fan systems little rubber trap doors that open up as the air pressure inside the shroud increases.
     
  8. billbrown
    Joined: Dec 24, 2007
    Posts: 595

    billbrown
    BANNED

    the pump is not for a serp style. the shrouded fan had no effect compared to the non shrouded fan. mechanical fan is out of the question. i tried the restrictor today because i was told that it may be flowing through the radiator too fast. there is no hood. it is angry. i would be o.k with 210, but it just keeps creeping up. The radiator is about 1 inch bigger than a 65 mustang radiator, but is SUPPOSED to cool 700 hp. I sure as shit dont have that. I forgot to mention that even creeping through town the temp starts rising. I seems like the slower i go the cooler it stays. im really confused.
     
  9. billbrown
    Joined: Dec 24, 2007
    Posts: 595

    billbrown
    BANNED

    i really appreciate the help though.
     
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 49,263

    squirrel
    Member

    I'm guessing a bigger radiator (more area, not thickness) is what you really need...I know you don't want to hear that. The radiator in my 55 is huge, it barely keeps it from boiling in the arizona summers.
     
  11. billbrown
    Joined: Dec 24, 2007
    Posts: 595

    billbrown
    BANNED

    thats what im thinking too. im NOT wanting to run some dumb auxillary radiator in the rear. there isnt too much room left though for a bigger radiator. Should of went with a small block. life is hard.
     
  12. Home Brew
    Joined: Oct 12, 2007
    Posts: 97

    Home Brew
    Member

    I had heating problems with my second Willys with a big block. I used an aluminum water pump and added by pass lines from the rear of the intake to the thermostat housing. Ran 200 hundred all the time. Didn't matter if it was at idle or running at highway speeds. I find that the newer motors tend to run a little hotter.
     
  13. AutoArt66
    Joined: Apr 3, 2010
    Posts: 274

    AutoArt66
    Member

    BBC and 37 engine compartment is a tough combo. Get the biggest brass radiator you possibly can in there with a good clutch fan..... I would remove the shroud to improve overall air flow... If it is still continuing to climb start experimenting with different temp thermostats which will control the flow at different rates. Also I have run Napa Cool which seemed to help with my nasty BBC. Best of Luck you will find the solution.
     
  14. sdluck
    Joined: Sep 19, 2006
    Posts: 2,749

    sdluck
    Member

    Do you have a vacuum advance does it work? What pulleys are on it,the water pump needs to be overdriven.Pictures will help
     
  15. sdluck
    Joined: Sep 19, 2006
    Posts: 2,749

    sdluck
    Member

    How much coolant?
     
  16. slammed
    Joined: Jun 10, 2004
    Posts: 8,151

    slammed
    Member

    Really, Elpolacko hit it on the head. At 55mph that air flow should keep it cool. Even without a fan! The restrictor needs to go. Correct thermostat installed. How much CFM does the electric fan pull? You may need 2 that total more CFM than a single large one. Making sure there are no air pockets is good advice.
     
  17. Mr48chev
    Joined: Dec 28, 2007
    Posts: 29,546

    Mr48chev
    ALLIANCE MEMBER


    Yep, do you have the correct pump for the belt system you have?
     
  18. dodored
    Joined: Feb 5, 2007
    Posts: 640

    dodored
    Member
    from Concord NC

    How much cam do you have? Large overlap don't contribute too much to running cool. It could be so many factors that its really going to be a trial and error hunt for the actual culprit.
     
  19. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 26,981

    Jalopy Joker
    Member

    are you running a heater? if not, did you run a loop hose or block off hose connections?
    running no hood can more problems than having one-need fresh air flow in and a way for hot air to exit engine compartment.
     
  20. Muttley
    Joined: Nov 30, 2003
    Posts: 18,456

    Muttley
    Member

    Have you checked to make sure the bottom hose isnt being sucked closed?
     


  21. This was going to be my very next question.

    ------------------------------------------------------------------------------------

    With a restrictor, the bypass shouldn't be necessary. If you are running a thermostat, the bypass is a must.

    Don't go around thinking an SBC would have been easier.

    Oh, and I would love to see the math behind your 700 HP radiator that is slightly larger than the popular Mustang Radiator. I have seen Ron Davis rate his radiators similar in the past, and ones that rate in the heat rejection range to support that are much larger.

    To rate a radiator by HP is kind of a gimmick. You can calc out how much heat is generated per HP but how the engine deals with it is quite another thing. At what CFM of air flow through the core and at what temps were used to determine heat rejection efficiency to get those numbers would be very helpful to match their claims.

    Like Jim's 55, my twin turbo'd BBC in my 63 F100 here in PHX AZ can run quite hot. With the AC on and sitting in traffic it isn't unusual to see 220 or 230. But I never boil over and that is far more important.

    Because the radiator is mounted low compared to the top of the engine and I have a double pass radiator, steam pockets were displacing coolant and causing me all sorts of grief. I ended up changing my system to a surge tank similar to what is used in late model vehicles and that solved my issues.
     
  22. nofin
    Joined: Jan 7, 2010
    Posts: 321

    nofin
    Member
    from australia

    If you get a second temperature sensor and put it on the radiator, that will tell you if the radiator is big enough. If you have hot engine and cool radiator then it's most likely a soft hose or the restrictor plate not allowing enough flow. If they are the same temperature then you might need to get a bigger radiator, or improve the air flow through the one you have.
     
  23. overspray
    Joined: Jan 14, 2003
    Posts: 1,232

    overspray
    Member

    My most memorable Big Block cooling problem ended up being too large of a diameter water pump pulley. I dropped it 1 inch in diameter and it cooled down even idling in a 4th of July parade at 95 degrees outside temperature. Of course, this was after much money was spent in other directions without any cooler results.
     
  24. 1971BB427
    Joined: Mar 6, 2010
    Posts: 6,899

    1971BB427
    Member
    from Oregon

    The usual problem with a BBC is cooling at idle. With your BBC running hot at higher rpm's I'd guess it's just a matter of cooling capacity. It may be from an engine that's been bored out, and the cylinder walls are a bit thinner, but I don't know what's been done to your engine.
    Griffin makes a small drag race radiator that has no filler neck, just 1.5"x1.5" inlet/outlet, so it can be mounted in any position and not be an issue. It's about 16"-18" square if I rmember correctly, and not too spendy. I'd look at finding a place under the car to mount one with a small fan pushing down on top of it.
    Had the same issue on my 427 bored .060" over, but room was not an issue, so I just got the biggest, thickest radiator I could find and built mounts to locate it in the old location.
     
  25. billbrown
    Joined: Dec 24, 2007
    Posts: 595

    billbrown
    BANNED

    Elpolacko. you are my hero. Thanks for the help guys.
     
  26. Bingo! Look at any 60's full-size Ford and you'll immediately understand the concept. Low hood line, cross-flow radiator, heads maybe higher than the tank, it all adds up.

    Bob
     
  27. dragsta
    Joined: Apr 11, 2010
    Posts: 589

    dragsta
    BANNED

    is it possible that your pump pulley is turning too fast at highway speed? did you change the pulley ratio? like a boat propeller, if it turns too quickly it will not work efficiently.
     
  28. mustangsix
    Joined: Mar 7, 2005
    Posts: 1,297

    mustangsix
    Member

    Sounds to me like the radiator area and airflow are marginal for the heat you produce.

    First, I'd add a good thermostat and get rid of the restrictor.

    Then, I know you don't want to add other coolers, but an oil cooler can remove a considerable amount of heat and reduce the load on the cooling system.

    Also, take a look at the engine compartment to see if you can get more air moving thru there. With some early cars there just isn't going to be enough space around the engine for air to exit and you may need to add some louvers or remove a panel.
     
  29. Avert your eyes traditional dudes!

    Here is my set up, you can see the bypass hose I made from the intake to the surge tank (degass bottle) and some of the heater plumbing as well. The small line from the radiator hose to the surge tank is to help clear any trapped air in the radiator.

    [​IMG]

    [​IMG]
     
  30. Hot Rod Porn... very impressive and simple. The only other alternative is to conjure up a water-neck adapter and mount a traditional Ford type tank.

    Bob
     

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