1. Sonny

    Sonny It’s all fun til the rabbit gets the gun.

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    The 75mph test is listed above. 196-198* but required both electric fans on to keep it there.
    My old rad had square top.
     
  2. Sonny

    Sonny It’s all fun til the rabbit gets the gun.

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    Rechecked my timing and total was only 31! Upped it to 37 and it’s much happier. And runs strong! Never went past 197 on the highway with Florida heat at 88. Idles and runs so much smoother.
     
  3. Wietse

    Wietse Well-Known Member

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    I believe these thermostat specifications are given at what temperature it starts to open.
    So a 180* thermostat starts to open at 180* and, depending on make/model, will be fully open 10* or 15* higher.
    Say it is full open at 190* and your coolant temperatures are higher then that, it shows your cooling system is being used at its full potential already.
    But in a good system you should be seeing 190* only at continues full load, not something our cars will ever see.
    But it is good to know at what temperature your thermostat is fully open so from that you can have a good judgement on how your cooling system is performing.
     
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    • PRHeads

      PRHeads Well-Known Member

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      My feeling is that the radiator just can’t keep up.

      I’ve had a couple of vehicles that exhibited very similar characteristics to what the OP is seeing.
      They were both 100% stock....... and never had any problems until the radiators started getting shot.

      They both did the same thing...... thermal runaway at highway speeds.
      The faster you went, the hotter they got.

      Replaced the radiators...... problem solved.

      Whether it’s the air flow thru the radiator, or the radiator itself isn’t efficient enough to dissipate the heat quick enough, I have no idea........ but I don’t think the coolant temp is dropping enough on its trip through the radiator, and that’s the root of the problem.
       
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      • Sonny

        Sonny It’s all fun til the rabbit gets the gun.

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        Unfortunately I’m using a new champion 3 row I bought last year. I have an infrared heat detector coming tomorrow to look for hot spots.
         
      • Heimedw

        Heimedw Well-Known Member

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        I did a 512 last year and have been lucky with my cooling system. My car runs 180f down the highway and will run 200-205f if I get stuck in traffic. It always cools down out on the highway. You are saying that you are running hotter on the highway. This would make me believe that you are not getting enough air flow through the rad? Possibly your cooling fans and shroud. Or the rad is not sufficient enough. I also run 355 gears and I have no rad shroud with the stock 64 fan. I have been considering buying the stock 64 shroud from classic car industry.

        One other thing I just noticed in your pitchers are your electric fans set up to pull air through the rad or push air out through the rad? They should be pulling air through the rad into the engine bay? Just a thought
         
        Last edited: Jul 21, 2020
      • Wietse

        Wietse Well-Known Member

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        Maybe try and slap a mechanical fan back on with a shroud and see what it does.
         
      • Sonny

        Sonny It’s all fun til the rabbit gets the gun.

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        Pull.
         
      • Sonny

        Sonny It’s all fun til the rabbit gets the gun.

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        I just realized that six months ago I spray painted the front of my champion radiator with barbecue grill paint. I wonder if that was causing the reduction in cooling running down the highway?
         
      • David Stillie

        David Stillie Well-Known Member

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        Mine is painted black......no issues.
        FYI I had issues with electric fans not cooling. All problems went away when I put a clutch fan on.
         
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        • myk r sanchez

          myk r sanchez Well-Known Member

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          We're they spinning in the wrong direction?
           
        • Wietse

          Wietse Well-Known Member

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          I know there is "special" radiator paint that supposed to not obstruct the heat transfer.
          Unless you sprayed some serious black tar on it i guess it will not make a real difference.
           
        • Jeff Erwin

          Jeff Erwin FBBO Gold Member FBBO Gold Member

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          OK, I gotta jump in here because there's something I don't completely understand. (well, there's a LOT of things I don't understand, but...)

          My SBee 440 was running what I consider hot. The temp gauge was at the upper end, typically about 85%. It would run up and touch the top end when warming up, then back down as the thermostat opened so I know things were working, but it seemed pretty high to me. Knowing these gauges aren't always completely accurate I decided to check so I pulled the thermostat to see what I had. Sure enough, a 195 degree. So, as part of my science project I put a 165 degree in to see what would happen. Sure enough the gauge is now between the first two lines at the lower end, what one might see as the 'normal operating temp' on the gauge. Running cool. From some of the threads here I am hearing that the 440 doesn't really like to run that cool, but my Bee is a bit of a garage queen so I don't really worry about the temp as long as it isn't pegged at the top end.

          So here's my question. If the thermostat opens once the stated water temp is reached (say 165) which then runs the water through the radiator, how does it keep the temp down to 165? I assume the 195 thermostat did the same thing but opening at 195. However, once opened, is there any difference between the thermostats? They aren't going to close when the engine is running, so they should be operating identically once fully opened. Open flow is open flow.

          But they don't.

          So, here's the conclusion I have reached:

          1. I am wrong to assume that without a thermostat the engine would run hot. This was my basic assumption which didn't fit the facts. I suspect now that without a thermostat at all the engine would run in the 150-160 range. I have been working on cars for 50 years, this is news to me. OK, I'm slow. Radiators were never my thing, more of a carburetor guy.

          2. If #1 is right, the 195 degree is restricting water flow so it gets hotter with less frequent exposure to the radiator. Is the opening smaller? It kinda has to be for this all to work. I've never noticed that.

          3. Does it really bother my engine to be running at 165? I kinda like the gauge in the lower 1/3 of the range, from my experience with Mopars going back half-century it makes me nervous when the gauge is at the high end. Bad things live there.
           
        • khryslerkid

          khryslerkid FBBO Gold Member FBBO Gold Member

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          That depends on the cooling effectiveness of the radiator, fan and water pump flow. Also outside temperature. It could run on the cool side.

          Correct

          If you're running @165 on a 75 degree day you have a great cooling system! The T-stat only controls the low operating temperature. What happens above that temp is dependent on the cooling system, timing ect.
           
        • Wietse

          Wietse Well-Known Member

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          You need to know that a thermostat has 2 readings that are important actually.
          A thermostat has a temperature where it begins to open and a temperature for full open.
          For most car spec thermostats only 1 spec is given, but could be tested in a pan of water and heat it and check. (I.e. a 180* thermostat will start to open at 180* but will be fully open at 195*)

          A thermostat will regulate the temperature by cracking open at its set temperature, and only a partial flow of water goes through the radiator and gets cooled.
          The remaining water returns to the engine block directly without cooling but will be mixed with the cooled water returning from the radiator.
          The hotter the water the more the thermostat opens and increases the flow/volume of coolant to the radiator, till a temperature point where the thermostat is fully opened and sends as much water to the radiator as possible.
          If temperatures of the cooled water are too low the water temperature that comes out of the engine will be too cold, and the thermostat will start to close, allowing the engine to stay warm.

          If a thermostat is at full open and the temperatures continue to rise it means your cooling system is not capable of providing enough cooling.
          If you would run no thermostat the engine would not reach normal operating temperature and will remain cold. (this assuming you have a capable/good working cooling circuit)
          An engine requires to be at normal operating temperature for a cleaner combustion, running an engine too cold will increase carbon deposits in the combustion chambers and foul the engine.

          If your car is not a racer i would stick to a standard thermostat for your engine, a 440 does require a healthy cooling system to stay cool.
           
        • 64fury74charger

          64fury74charger Well-Known Member

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          Just tossing in my 2 cents

          Both of my cars have a high flow pump and flex fan. Both have Champion aluminum radiator, the Charger a 26” and 22” in the Sport Fury. Factory shroud on the Charger and no shroud on the Fury. Both cars run the same 180*Stant t-stat and premix 50/50 coolant . Both cars temps run 185 once warmed up regardless of idling in heavy traffic or driving at speed. Both cars reach 190 as the thermostat opens and fall right back to 185. Both aluminum radiators are over 6 years old and have not had any cooling issues to date.

          I am not a big fan of electric cooling fans or clutch fans but that’s just me. I like to try and keep things simple. I have always addressed the cooling system first on any vehicle before doing anything else to the motor etc.
           
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