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Thread: sbc overheating

  1. #1
    Join Date
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    Default sbc overheating

    I just finished installing a rebuilt 350 performance engine in my 72 camaro. After only a few minutes of driving the temp is @ 210-220.
    Does anyone have any suggestions where I should start looking for the problem?



  2. #2
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    what type of fan are using? Stock? Electric? What degree thermostat do you have?
    My Current Project

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  3. #3
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    It's the stock fan and I am not sure about the thermostat

  4. #4
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    Does it matter how fast you're going? In other words, does it still overheat at highway speeds?

  5. #5
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    do you feel the air being pushed into the radiator? Any fan shroud?
    My Current Project

    1955 Chevy 150 - aka John Doe
    http://imageshack.com/a/img540/4479/wtNiuH.jpg

    Toys:

    1968 Camaro
    http://imageshack.com/a/img901/7223/twfpl9.jpg

    1956 Chevy 210
    http://imageshack.com/a/img834/6076/8azy5.jpg

    ___________
    Jeff

  6. #6
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    Default

    Have you checked the timing. Just a thought.. And check to see if the thermostat is actually opening with a couple of screw drivers or throw it in a pot of hot water.

  7. #7
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    Did you use the same carb with the old jetting? It could be running lean and making it get hotter very quickly.

  8. #8
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    There are so many reasons for this.. You just have to eliminate one at a time. See if it cools down at cruising speed or if it stays hot all the time.

    I usually make sure the t-stat works by boiling it, them make sure both upper and lower hoses are getting hot to ensure proper flow and the water pump is doing its job.

    Also, make sure the gauge is getting a correct temp!! A wrong sender will do this or if its in the head vs. the intake. Best bet is to run it at idle and with the radiator cap off and use a gauge to get the actual temp of the coolant in the radiator.

    Good luck!

  9. #9
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    If you increased compression or cubic inches, jet your carb up about 4 sizes front and back. When I put my 650 dp Holley from my 327 onto my 383, it immediately was running 220. I jetted it up and it ran 185. Later, I went to a 750 Mighty Demon and it cooled even more.
    One thing to look at is if the paint is "cooking" on the headers just off the heads at the exhaust port....you know you're lean for sure.
    Also - you could have air pockets in the engine. I cured that by drilling an 1/8" hole in the perimeter of the thermostat. That solved that part (and then required some coolant to be added).

  10. #10
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    Like cad said, drilling the t-stat is a good idea. I did 3, 1/8" holes to allow for some flow and any air to escape.

  11. #11
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    +2 on the holes in the t-stat.

    Also, is the lower hose reinforced to prevent being sucked closed.
    Nick R.
    69 Camaro - 383, 700R4, 12 bolt 3.55, Hotchkis, Bilstein, Global West, Morris Classic
    08 HHR SS - Still Stock for now
    Do you still believe in all the things that you stood by before? Are you out there on the front lines, or at home keeping score?
    Do you care to be the layer of the bricks that seal your fate? Would you rather be the architect of what we might create?

  12. #12
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    Can you put your hand on the upper radiator hose when it gets that hot? If you can the thermostat is not opening.
    VaporWorx. We Give You Gas http://www.vaporworx.com
    Carl Casanova's 1968 Camaro

  13. #13
    Join Date
    Jan 2008
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    Thanks for all of the help guys! I installed a new thermostat and it is staying at around 170 all day. This is the first time I have posted a question. You guys are awesome! I am learning slowly but having a great time. I will post some pics soon.

    Thanks again!!!!!!!



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