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Hot Rods Why does my SB overheat/ run hot?

Discussion in 'The Hokey Ass Message Board' started by BaBa, Jul 9, 2021.

  1. BaBa
    Joined: Jun 2, 2011
    Posts: 114

    BaBa
    Member

    Have a 350 Chev in my 49 AD pickup. It always runs hot (200deg+) especially at lower speeds. In fact now that I live in AZ if I drive for any length of time it overheats.
    350 out of a 74 Camaro, no smog, TH350 trans, Erson cam, Quadrajet. Champion AL radiator with electric fan, fan is set for about 160, had std water pump, went to Hi Perf water pump w/ no change. 180 thermostat tried running w/o but no change.
    Timing is right, jetting is right hoses are good. It has 40 Below radiator additive and fresh coolant.
    Could maybe change to std fan with an adapter since the block sits low compared to the radiator but the electric moves lots of air.
    Any ideas?
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 49,329

    squirrel
    Member

    first idea....show us some pictures of the engine, radiator, fan, etc from a few different angles.

    Then we can see what you're working with. otherwise, we can only guess.
     
  3. Photo's would help, one question, what size is the electric fan and does it cover the radiator? HRP
     
    dana barlow likes this.
  4. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,059

    Doublepumper
    Member

    Have you checked it with a different temp gauge? Possibly the one you're using now isn't accurate.
    Timing can have a big effect on heat. Not enough initial timing or advance/s not working correctly will cause temp to be higher than normal.
     
    Joe Travers likes this.

  5. So,, , you have no fan,,,but the electric fan ?
    All fans are not created equal,,,,,some work better as just an auxiliary fan .
    Like Jim said,,,,,pics will be very helpful .

    Tommy
     
    GlassThamesDoug likes this.
  6. sdluck
    Joined: Sep 19, 2006
    Posts: 2,751

    sdluck
    Member

    Is the vacuum advance hooked up to manifold vacuum,timing should be 12 to 14 BTDC,full advance by 2800.
     
  7. Joe Travers
    Joined: Mar 21, 2021
    Posts: 341

    Joe Travers
    Member
    from Louisiana

    I jet toward the fat side for the Summer. It will lean out when temps drop. You would be surprised what a 5% jump up in fuel mixture can do if you're riding on the border.

    Joe
     
    jimmy six likes this.
  8. FrozenMerc
    Joined: Sep 4, 2009
    Posts: 2,737

    FrozenMerc
    Member

    Rule #1: If it overheats driving down the road at 30+ mph, you do not have enough radiator and it is time to find one with more heat rejection capability.

    Rule #2: If it overheats idling or in traffic, you have an air flow problem and you need to get more air across the radiator. Better flowing fans, shrouds, etc are the fix here.

    There is nothing wrong with running at 200, especially if that temp probe is located in the cylinder head like most SBC's I have seen. As you found out, a high flow water pump does not cure overheating problems. Pushing more coolant across the rad does not change the heat rejection rate of the radiator one bit, all that accomplishes is a reduction of the temperature difference between the inlet and outlet coolant temps. You need a rad with more rows, more fins, and/or more surface area in contact with the air in order to increase the amount of heat energy transferred to the air, especially in a hot, low humidity climate such as Arizona.
     
  9. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 4,927

    Lloyd's paint & glass
    ALLIANCE MEMBER

    So it runs hot, but never boils over? Like it'll run 210/215 on the gauge, but doesn't actually overheat? Where are you picking up your temp from? Cylinder head? Coolant passage on the front of the intake? Cylinder head is gonna show a higher temp, there's no way around it. I run a 180 thermostat (at least i think that's what is in there) never overheat, but my sending unit is in the head, and i usually run 215 degrees on the gauge.
     
  10. Joe Travers
    Joined: Mar 21, 2021
    Posts: 341

    Joe Travers
    Member
    from Louisiana

    True. Original thermostats were usually rated fully open @ 210F. Modern designs run there all day long for emissions control but timing and fuel mixture are constantly being regulated by control systems. Older engines have to be tuned for standard conditions.

    Joe
     
    anthony myrick likes this.
  11. Budget36
    Joined: Nov 29, 2014
    Posts: 6,780

    Budget36
    Member

    If it overheats at road speed without the thermostat, I’d say the radiator is the issue.
     
    olscrounger likes this.
  12. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 4,927

    Lloyd's paint & glass
    ALLIANCE MEMBER

    Guess i missed that part. Great big radiator, plenty of volume, with lots of transfer surface.
     
  13. BaBa
    Joined: Jun 2, 2011
    Posts: 114

    BaBa
    Member

    Here are some pics. I ditched the shroud when I changed radiators because it was overheating with the stock (new) radiator. I had one of these trucks years ago with an Olds V8 (325?) with the stock radiator and it never overheated. The timing is set correctly and the advance works. I'll get another gauge and see if that helps or reads different and it has never boiled over because when it pegs the gauge I get spooked and I've always been somewhere where I could shut it down to cool off.
    Thanks for the help so far.
    [​IMG]
    [​IMG]
    [​IMG]
     
    Last edited: Jul 9, 2021
  14. He said now that he is in Arizona it gets hot ,,,,,,everything is hot in Arizona .
    It does sound like he has a cooling issue,,,and not an air flow issue .

    I don’t see any pics,,,,just an advertisement for photobucket and trying to get me t9 sign up .
    Nope,,,not me .

    Tommy
     
  15. hepme
    Joined: Feb 1, 2021
    Posts: 65

    hepme
    Member

    All the above but i didn't see anything about a shroud, assuming you have, or have tried, a mech. fan.
    --and a "pusher" electric is not nearly efficient as a "puller" mounted in back of the rad. -if that's what you have. A combo of a 6 blade, hi pitch flex fan about 1" behind the rad. with a shroud that covers 1/2 the blade surface all the around, a pusher in front for slow, stop traffic (switch activated), a tstat, and a quality radiator designed for high heat should cure the issue. Now, like the others said, have you checked your timing?
     
  16. Radiator looks good,,,,what about in front of it,,,,,does it have an area that will let air to the radiator ?
    Tommy
     
  17. BaBa
    Joined: Jun 2, 2011
    Posts: 114

    BaBa
    Member

    I'll check the timing again too.
     
  18. BaBa
    Joined: Jun 2, 2011
    Posts: 114

    BaBa
    Member

    I'll have to look at that again. Might have to move the condenser from the AC away from the radiator to let it breathe better.
    Already put a transcooler underneath so the trans heat wouldn't affect it.
     
    Desoto291Hemi likes this.

  19. What he said!!

    Ben
     
    jaracer likes this.
  20. Baba,
    That might make all the difference .
    Check that closely .

    Tommy
     
  21. SPEC
    Joined: Feb 1, 2021
    Posts: 310

    SPEC
    Member

    Check the bottom hose it should have a spring in it. Without a spring the hose will collapse and cut off the coolent flow.
     
  22. BaBa
    Joined: Jun 2, 2011
    Posts: 114

    BaBa
    Member

    Hoses are good.
     
  23. Tman
    Joined: Mar 2, 2001
    Posts: 34,488

    Tman
    ALLIANCE MEMBER

    Its gotta be the fugly Edelbrock valve covers and air cleaner! ;)
     
  24. squirrel
    Joined: Sep 23, 2004
    Posts: 49,329

    squirrel
    Member

    How big of a mechanical fan can you fit in there? It's hard to tell from the pictures, perhaps one that shows the water pump pulley, would give is a better idea.

    That electric fan isn't going to move enough air, it's just not one of the better ones.

    btw, normal operating temp for me in AZ is 180 to 230. When it gets over 230, time to figure out something to fix it. I prefer either a clutch fan if it will fit, or a large flex fan with fat, curved blades. And a shroud.
     
  25. BaBa
    Joined: Jun 2, 2011
    Posts: 114

    BaBa
    Member

    Ouch! shoulda put an LS in it.
     
    Lloyd's paint & glass likes this.
  26. What,,,,,and get banned from here,,,,,,,LoL.
    No LS stuff .

    Listen to Jim,,,,,more times than not,,,he’s right .
    Plus,,,he’s from Arizona,,,,been there most of his life I think ?

    Tommy
     
    Jim Bouchard likes this.
  27. BaBa
    Joined: Jun 2, 2011
    Posts: 114

    BaBa
    Member

    You are probably right. I did the electric because it was easier to fit in and I didn't have to do a water pump adapter to move the fan up closer to the radiator C/L. I'll try moving the condenser first, checking the timing and if that doesn't do it, I think I can squeeze a mechanical fan in there.
    Appreciate everyone's help. I've got some homework to do but pardon me if I don't do it soon, it's 105 and my shop doesn't have AC.
     
  28. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 4,927

    Lloyd's paint & glass
    ALLIANCE MEMBER

    I think that was just a little smart assery on his part Tommy ;)
     
    '34 Ratrod and Desoto291Hemi like this.
  29. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 4,927

    Lloyd's paint & glass
    ALLIANCE MEMBER

    I'm with ya man, i came in a few minutes ago from sanding body filler all day, mixed with sweat, it looked like i was covered in pancake batter lmao! o_O
     
    bchctybob likes this.
  30. olscrounger
    Joined: Feb 23, 2008
    Posts: 4,331

    olscrounger
    ALLIANCE MEMBER

    that elec fan looks inadequate--I use Cooling components and Walker radiators--they have a shroud as well--have worked well for me in 105 degrees in traffic with ac on--done maybe 10 40's this way.
     
    RICH B, lippy, Jim Bouchard and 4 others like this.

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