Changing thermostat. Any firm recommendations?

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  1. biomedtechguy

    biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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    EDIT: Hotter may, in fact be better if for no other reason than power production. See linked article.
    https://www.allpar.com/fix/engines/cooling-system-about.html
    I have read the long "tuning a six pack" post that is adamant about everything that is stated in it, and that includes running a 190 degree thermostat to prevent fuel puddling. My inclination is to go 180 degree, and that "cooler engines are happier". I have a 70 V-code Roadrunner with the ALUMINUM Edelbrock/Chrysler 6bbl intake. Aluminum valley pan gasket has crossover heat passages blocked, TTi headers, manual transmission, 71 440 steel crank, heavy rods. Adding Vintage Air AC system I just bought soon. Live and drive/race in the Deep South.
    But now is the time to decide, because I am installing a Cold Case radiator and the only way I can think of to thoroughly flush all of the old coolant out of the engine is to run fresh water through the engine with the thermostat removed, otherwise the thermostat will be opening and closing and I can only flush out the radiator, let the engine draw that fluid in, circulate one the temperature rises, stop it, flush radiator again, repeat.
    So those are my 2 questions.
    Am I right in thinking that removing the thermostat is the best, most thorough way to flush out all of the old coolant,
    AND
    what temperature thermostat should I run, should it, in fact, be the 190 degree recommended or is my intuition right and 180 degrees for a cooler running engine the better choice?
    Lastly, what brand and part # is the absolute best thermostat to get? Stant?
     
    Last edited: Oct 21, 2019
  2. GetX'd

    GetX'd FBBO Gold Member FBBO Gold Member

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    Super Stant - 180*
     
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    • 68Moparmaniac

      68Moparmaniac Well-Known Member

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      40320055_081913_sm_x700.jpg
       
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      • biomedtechguy

        biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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        Here's an article on coolant, including Evan's waterless coolant. Seems like the Evan's is particularly good to prevent pinging, and although I have plans to get aluminum heads, I'm running cast iron now, and the 421 in the GTO is going to have iron heads (they've been ported) for the foreseeable future.
        https://www.allpar.com/fix/engines/coolant.html
         
      • toolmanmike

        toolmanmike Moderator Staff Member FBBO Gold Member

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        No need for that expensive stuff unless you are fighting a overheating issue.
         
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        • wagonman

          wagonman FBBO Gold Member FBBO Gold Member

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          Stant 180 X 2
           
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          • ddpsnake

            ddpsnake Well-Known Member

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            make sure what ever stat you get it has a 1/8 hole drill in it,prevents trap air.
             
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            • RJRENTON

              RJRENTON FBBO Gold Member FBBO Gold Member

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              When the Tstat opens, any entrained air will escape to the radiator. The 1/8" diameter hole is to allow air to escape during filling the system. It serves no other purpose. Just my opinion of course.
              BOB RENTON
               
            • 70sixpkrt

              70sixpkrt Well-Known Member

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              Regular Stant 180.
               
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              • 1 Wild R/T

                1 Wild R/T Well-Known Member

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                Robert Shaw...
                 
              • Dennis H

                Dennis H FBBO Gold Member FBBO Gold Member

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                Next we’ll hear from the Evans boys. 180 Stant Superstat. Green coolant.
                 
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                • MoparLeo

                  MoparLeo NRA PATRON LEVEL LIFE MEMBER FBBO Gold Member

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                  Test and/or replace the cap as well. Often overlooked and a common cause of boil overs due to not holding the cooling system under proper pressure.
                   
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                  • threewood

                    threewood Well-Known Member

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                    Gates 33038 or Stant 13478
                    Both are 180 degree.
                     
                  • biomedtechguy

                    biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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                    New cap comes w/the new Cold Case radiators.
                     
                  • RJRENTON

                    RJRENTON FBBO Gold Member FBBO Gold Member

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                    WOW!!!! A free new cap comes with the $350 radiator.....what a deal...
                    BOB RENTON
                     
                  • MW 413

                    MW 413 Well-Known Member

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                    I've been running a 160 hi-flow stat in my AAR 340 6 barrell for 40 years with no problems. I also only run a 7lbs cap. No issues. Dash gauge needle runs right at bottom of op temp range. 190 deg stats were for emissions only. If your carbs are set up properly you will not have gas pooling in manifolds at 160-180 op range. Gas pooling on these engines is also due to 190+ op temps and the engine temp rise on a hot day for the 20 minutes after hot shut down when the engine coolant temp can climb to 220 degs and boil the gas out of the carbs and into the manifold making it flooded on a hot restart.
                     
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                    • biomedtechguy

                      biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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                      Regarding hot restart, the 1st article I linked agrees.
                      Regarding power, and engine temperature, here's an excerpt:
                      In an engine, by reducing the difference in temperature between the combustion gas and the engine metal, you cut the loss (waste) of heat from the combustion gas, so more energy stays in the combustion gas, which is doing the work of pushing the piston. Smokey Yunick wrote in his highly-respected book Power Secrets: “Some guys go to great lengths to keep the engine temperature down … though the engine doesn’t overheat, they don’t realize that they’re putting energy (heat) into the cooling system that could be used to produce power at the crankshaft. Running the engine at 180 degrees will drop the overall horsepower by 2%-3%. For max power the cooling temp should be at least 200 degrees.”
                       
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                      • Dennis H

                        Dennis H FBBO Gold Member FBBO Gold Member

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                        Thermostat housing can be a pia. Mancini Billet solved mine.
                         
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                        • threewood

                          threewood Well-Known Member

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                          And fwiw, the last few Stant I have tested on the stove have opened late. The 180 I last tested opened closer to 188. I then tried a new 195 and it opened late as well and kept the temp steady at 205. I replaced it with the old one as 188-190 degrees seems to run fine with little to no creep up at idle.
                           
                        • 68 HEMI GTS

                          68 HEMI GTS Well-Known Member

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                          I normally run a 180, works well for most things. Running it hotter is better for the engine to a point. The issue with running it at 200 is you’ve lost 20 degrees of buffer if you get into a traffic jam situation. As far as the whole power thing, I tried several thermostats in my Dart. The car was a solid .1 faster with a 160 over a 180. Not that that would be the case for every application but, it tosses a wrench into the equation that you’re referring too. Intake temp plays a big role in power production. That’s why guys ice the intake at the track. You raise engine temp you raise the temp of the intake.
                           
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