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Hot Rods Hemi is hot!!!

Discussion in 'The Hokey Ass Message Board' started by moparjimd60, May 31, 2020.

  1. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    Hello all, I am looking for advice on solving an overheating problem on my 354 blown hemi. I have a Chinese aluminum radiator in my 32 Ford grill shell, with a derale puller fan 2400 cfm. I am running ac on it also , all that being said it warms up like a typical hemi slowly but seems to build heat the longer I drive . But at 55 or so it will stay around 180 to 190 . On longer highway runs it will creep up to 200. It was worse so I removed the thermostat and it seemed to help but if I get into traffic or idling it gets hot quick. Now I’m flustered and don’t want to just throw money at it but am trying to work through it mythologically thanks in advance for all your help.


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  2. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    I knew I would forget something, I am running a short big block Chevy water pump


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  3. TRENDZ
    Joined: Oct 16, 2018
    Posts: 187

    TRENDZ

    Ignition timing can have a large effect on engine temp.
     
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  4. 99.99999999999999999999% of the time I have found air flow is the problem with overheating. Driving at speed fixing the heating problem supports that theory. My guess is your fan system is too restrictive. I have a 1936 Plymouth radiator (fits the Willys grille shell) on my '36 Willys for my 354 hemi and an aluminum bladed 16" blower fan (not the best setup but no room for a puller) and my engine runs a consistent 190F to 200F. My coupe is a gasser cartoon so has a tilt 'glass hood and no inner fender wells. I run an industrial centrifugal pump with turned down blades for water pump, cause no room for the stock pump either. Key is I have an extremely clear path for airflow.

    DFront.jpg engine top.jpg
     
    Last edited: May 31, 2020
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  5. Add a oil cooler. It took 30 degrees off my water temps. Let's see some pics.
     
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  6. Fordors
    Joined: Sep 22, 2016
    Posts: 2,753

    Fordors
    Member

    I was thinking along the same lines as @TRENDZ , look at your timing curve and see where your total timing is at your cruise RPM. Big tires and a relatively tall gear could make for not enough advance. I ran 31” tires with a 3.36 gear and 65 mph was around 2350 RPM, IIRC. If your total doesn’t come all in until 3000 RPM you may want to quicken that up.
    One other thing to consider is you may want to check your water pump drive ratio, make sure your combination of pulleys isn’t under-driving the pump.
     
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  7. Blue One
    Joined: Feb 6, 2010
    Posts: 10,519

    Blue One
    ALLIANCE MEMBER
    from Alberta

    Maybe It’s not overheating at all and it’s just a myth :D:D

    Maybe call on the Mythbusters:D

    I’m thinking that your fan is the problem.

    Electric fans are known for not moving air anywhere near their flow rating numbers and they can restrict airflow just by their physical presence when they are not running, sometimes even when they are running.
     
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  8. 73RR
    Joined: Jan 29, 2007
    Posts: 6,327

    73RR
    Member

    A lot of good points above. My first question is, where is your temp gauge plugged in? and, have you verified its accuracy?
    Most certainly check your timing numbers and make sure that you are not over 35 deg total. The EarlyHemi does not like bigger numbers.
    As Blue One notes, electric fans can be less than optimal and airflow through the radiator is a big factor in cooling. If the air isn't picking up/removing the heat as it goes through or, if the radiator doesn't have enough surface to discharge heat, then the heat stays in the system. The same problem can exist if you run without a t-stat; the water does not stay in the radiator long enough to transfer stored heat.

    .
     
  9. Blue One
    Joined: Feb 6, 2010
    Posts: 10,519

    Blue One
    ALLIANCE MEMBER
    from Alberta

    Good point, he mentions removing the thermostat which usually makes the problem worse.
     
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  10. foolthrottle
    Joined: Oct 14, 2005
    Posts: 1,033

    foolthrottle
    Member

    Pully size? I looked for chevy 396 water pumps with larger internal impellers designed for air conditioners.
     
  11. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    Thanks , not sure what else I can do on the fan it is all too close for a real fan.


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  12. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    I removed the thermostat and it actually helped which make me think the pump is not moving enough water.was thinking maybe an electric pump


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  13. hemihotrod66
    Joined: May 5, 2019
    Posts: 175

    hemihotrod66
    Member

    392 Hemi 1.jpg I had the same issue with the hemi in my 34 Ford...Had a US radiator triple flow radiator and it wouldn't cool the motor...Chrysler hemi motors have a coolant capacity from the factory of 24 to 26 quarts and I had a company called TCPP in Rexburg Idaho build me a radiator that has two rows of inch and a half tubes...Cured the heating issues....Will get to 205 on an extremely hot day here in Vegas...I run a Flowcooler big block Chevy water pump,,Cooling components fan and a 160 degree Tstat...You need enough water in the system to absorb the heat and move it to the radiator...Blowers develop heat on their own two because when you compress air heat is generated...Hope this helps some...
     
  14. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    Hi , yes I am reading the temps from the back of the drivers side head. I haven’t checked the calibration of the gauge but it is a new auto meter gauge.


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  15. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    [​IMG][​IMG][​IMG][​IMG][​IMG]



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  16. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    Thanks I am questioning the pulley size. The bottom pulley is smaller than the pump. If it were swapped it would overdrive the pump correct?


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  17. Joe H
    Joined: Feb 10, 2008
    Posts: 901

    Joe H
    Member

    Run hoses to the back of the truck and mount aux radiator or large heater core out of site. Doesn't really need to be in the air flow, its just a place to hold extra coolant. Use electric water pump, again out of site to move the water back to the front.

    Bottom pulley needs to be bigger then water pump pulley to overdrive the pump.
     
  18. tubman
    Joined: May 16, 2007
    Posts: 4,983

    tubman
    ALLIANCE MEMBER

    I think they guys suggesting an oil cooler are on the right track. When I built my dirt modified (engine in my avatar), all of the old-timers I knew kept telling me "If yer gonna run a hemi, make sure you have lots of oil in it". We build a special pan and added a big oil cooler, which resulted in a system that holds 14 quarts. We are running a radiator out of a 6 cylinder Valiant and we have to run the engine 10 to 15 minutes in the pits before each heat to even get the engine to 160 (there is no provision for a thermostat). I know it doesn't have a blower (against the rules), but it does have 12.5/1 pistons, an Engle roller tappet cam, and the other associated goodies.
     
    Last edited: May 31, 2020
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  19. Do you have a shroud with that puller fan? If not the only air flow from thre fan will be directly in front of the fan. Idealy a shroud covering the whole core, with the fan not dirrectly mounted to the radiator core would alow air to be pulled through the entire radiator. I agree with the adding an oil cooler and adjusting the timimg as others have siad as well.
     
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  20. Road Angels
    Joined: Mar 2, 2015
    Posts: 121

    Road Angels

    Tubes in the radiator look really small...the fan is only covering about 60% of the radiator area...also what type of impeller is in that water pump...cast...stamped> also is the blower over or under driven?
     
  21. spanners
    Joined: Feb 24, 2009
    Posts: 906

    spanners
    Member

    Careful over driving the water pump as you could end up with water cavitation at higher revs.
     
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  22. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    Hi it is a stamped impeller, the blower is 10 under I am not sure I have room for a shroud .


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  23. Deuces
    Joined: Nov 3, 2009
    Posts: 18,539

    Deuces
    Member
    from Michigan

    160° thermostat!......
     
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  24. Almostdone
    Joined: Dec 19, 2019
    Posts: 247

    Almostdone
    Member

    Not sure how much room you have (obviously not much), but some fan shrouds are pretty thin. Mine is about 1/2 inch thick. It covers the entire radiator and mounts a 16 inch Spal puller (the biggest and best fan I could fit).


    Also, out of the 16 or so replies thus far there are 3 suggesting an oil cooler, 3 bigger radiator, 2 timing, 2 thermostat, 2 shroud, and the rest had one reply each. Sorry, couldn’t help it.


    6090FA49-5369-461C-80D3-5ECA476D3C33.jpeg
     
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  25. 73RR
    Joined: Jan 29, 2007
    Posts: 6,327

    73RR
    Member

    Water flow at the back of the head is a bit 'sluggish' unless you are also pulling water from the rear of the intake rail. Note that HemiHotrod66 has a temp gauge mounted at the pump inlet which will give an accurate reading for the coolant going into the engine...you do have at least a 50-50 mix, right? but an additional gauge before the t-stat would be good to have in order to see the temp change. This could help define where the problem lies.
    The oem Hemi pulleys are about 5" bottom and 7" top, what are the gm numbers? Do not over speed the pump, as mentioned you will get cavitation and destroy the pump.
    Oil cooler? Excellent idea, even if a small one but, it needs to be in the air stream so that it too can transfer heat.
    I should have asked earlier, what is your total system capacity?

    .
     
  26. The cooling components unit is where I would start. I had that and a walker radiator on my 32 and didn't have a problem even with the ac on. But, that being said, you are accumulating heat sink with time. Anytime you really want to check a cooling system, go for a 200 mile trip and don't stop. It takes time for everything to heat up and get to the real temp of operation. Because you stated it heats up in traffic or stop signs, you have an airflow problem in my humble opinion.
     
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  27. Going with the poor air flow theory, as stated above most aftermarket Chinese plastic electric fans are woefully inadequate. Here is a great hot rodding option that Detroit designed and still looks reasonably hot rod. Just comparing these blades to the typical 16" thin fan you can see it moves seriously more air. Lincoln Mark VIII/Thunderbird fan is a robust 18" (air flow goes up with the square of the fan diameter so this fan nominally moves 25% more air than the usual 16" fan). 22" wide x 19" hi built in shroud. 6" deep. Also can be run as 2-speed fan with a controller. I put one on my '59 El Camino with a 305 SBC, fit like it was made for it. Always on ebaY for about $100.
    Mark III fan.jpg
     
  28. moparjimd60
    Joined: Jan 22, 2018
    Posts: 71

    moparjimd60

    Where did you get your shroud? That might work I think that would help, I see I have several opinion on where to start I have taken them all and plugged them into my situation, just can’t go buy a 700 radiator then 300 coolers and 400 water pumps I have to get it right the 1st time if I can I do appreciate all the input


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