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400 SBC heat problem?

Discussion in 'The Garage' started by Disciples Performance, Aug 8, 2006.

  1. Disciples Performance

    Disciples Performance 1/2 ton status

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    hey guys

    now i know the 400 sbc has a problem with overheating quite easily. Now im gonna throw a new high flow water pump into it, right away here and a thermostat. Now should that take the problem away for the most part? cause i cant see how other then those 2 ways it would overheat:confused: any other ideas?

    thanks
     
  2. big dan

    big dan 1/2 ton status Premium Member

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    one of those big fancy aluminum radiators would me nice.
     
  3. diesel4me

    diesel4me 1 ton status Premium Member

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    4 core..

    I had a 4 core radiator in my 74 K20 ,that had a 400SB from a 79 Suburban(I used the Burb radiator,it already had been replaced with a BB one)...despite the huge radiator,it still boiled over a few times,but most of it was my fault--

    I'd put my plow on,and forgot to "lock" the fan clutch spring so the clutch would stay engauged all the time,and it would overheat..it never gave trouble during "normal " driving,but did run a bit over halfway on the gauge..A bigger radiator would have been nice,like a diesel one,if I used the truck more in hot weather or for towing..:crazy:
     
  4. neverendingproject

    neverendingproject 1/2 ton status

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    Get aluminum. They are pricey, but a 2 core aluminum will dissipate heat better than a 4 core stock radiator.
     
  5. Disciples Performance

    Disciples Performance 1/2 ton status

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    ya ill look into a alum rad i can get one for like 150$ so might as well do it all right. Just so then i dont have to be as Paranoid haha
     
  6. Disciples Performance

    Disciples Performance 1/2 ton status

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    im almost tempted to bore it to a 406 lol but money pending haha
     
  7. 85mudblazin

    85mudblazin 1/2 ton status

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    High flow WP might hurt you. It will more the water alot faster so it will have less time in the radiator cooling before it enters the block.
     
  8. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Correct me if I'm wrong, but I believe the true nature of the 400's cooling problems lie within the coolant flow passages in the block/stock heads. Also a big ass radiator helps too.
     
  9. diesel4me

    diesel4me 1 ton status Premium Member

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    yep..

    You mean the LACK of cooling ports between the cylinders!..400's are "siamesed" bore motors,meaning there aint no coolant passages in between the cylinders like all the other small blocks..and naturally its larger displacement makes more heat--so its important to have a good radiator,and everything else in good working order,or you'll definately have overheating problems,much more so than say,a 350 block that has the cooolant passages in between cylinders..:crazy:
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    This has absolutely been beat to death on here, and simply isn't true, althought there are results to the contrary. The more time coolant spends in the radiator, the hotter the coolant in the engine gets, which is NOT good. People talk about outside temp, etc affecting whether too much flow is bad, however, components themselves will affect cooling, and only the owners have control over the condition of their parts.

    I won't spend any time writing up the why or how, if you need convincing, please do a search for the numerous threads on the subject.
     
  11. Disciples Performance

    Disciples Performance 1/2 ton status

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    lol somehow i got a double post of this sorry guys but awesome info ya im gonna do the alum rad idea. now the engine was rebuilt but not by me, but by someone who owned this engine/truck before me. And the guy that i bought it from did not know the mileage on the rebuild. it has a mild cam in it and edelbrock performer intake on it already headers etc so hopefully he did some stuff to the heads to allow better cooling, if not not biggie i will eventually bore it to a 406 so its all good for now. Better then my Peice of junk 305 gutlass crap lol
     
  12. MattK

    MattK 1/2 ton status

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    wouldn't increasing the bore even more increase the heat issue?
     
  13. Disciples Performance

    Disciples Performance 1/2 ton status

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    it will but by rebuilding it, it gives me a chance to fix all the mistakes lol i would put diff heads on it anyways etc
     
  14. sweetk30

    sweetk30 professional hooker Premium Member

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    take this for what is worth. 1ton 4x4 4.10 gears and 38" swampers. truck was 6500lbs . built to the hill 400sbc .030 over good strong cam , intake , fresh reman heads 76cc , slight dish pistions , knife edged crank , balenced bottom end , polished bottom end , and reman generic water pump.

    now i ran 87 oct gas in her. msd ign . she was smooth and power house.

    i tryed all combos of clutch fan and non clutch fan. shroud and no shroud. short old style rad and taller 81-up style rad. 3 core both. my temp never got past 215 at the most. 98% of the time was 210. mud truck and recovery rig. she just ran warm.

    check your system out for pluged rad tubes or other problems. also check for proper function of the gauge system. then if all else fails look in motor for heat problem.

    i would run a high flow thermostat if it was me. thay do help over stock style.
     
  15. Disciples Performance

    Disciples Performance 1/2 ton status

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    sweet thanx for the info dude. ya the 400sbc can be a power house first time ive owned 1 so im ready to see what she can do !
     
  16. 3 on the tree

    3 on the tree 1/2 ton status

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    I have run 400s in Burbs, Blazers and dirt track cars. No problems with overheating as long as I kept the cooling system top notch. I used stock radiators in the burb and Blazer (4 core), with shroud and good clutch fan. Even towing I never overheated. In my experience, the 400s do run hotter than a 350, and they WILL overheat quicker when the cooling system is marginal or defective.
     

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