Gentlemen: How do you look when you're hot?

Heating / Cooling / AC

  1. cruiser

    cruiser Well-Known Member

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    Hello all. Here's something I've been wondering about for a while. I've attached a photo of the temp gauge from my 1974 slant six powered Duster. This is what my temp gauge shows when the car is fully warmed up and operating at 70 mph. Does this look like yours? Does this look about right? Some specifics for my car: Totally stock engine, new high quality 195 degree thermostat, outside temperature was 30 degrees. Timing 10 degrees BTC, stock carb, auto trans. Gauge cluster professionally rebuilt and calibrated. New electronic voltage limiter in gauge cluster and new temp sensor in the cylinder head. If I'm doing the math correctly, straight up on the gauge would be 185 degrees. So if I'm running a stock 195 degree stat, I would think the temp needle would be about 1 1/2 needle widths to the right. It seems to be a bit more to the right than that. What do you think? Where does your temp needle stabilize at when fully warmed up? Thanks!

    IMG_2607.jpg
     
  2. leechris81

    leechris81 Well-Known Member

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    On a 30 degree day, the 318 in my ‘73 Swinger doesn’t even make it to the halfway point at 70 mph. The heat blows hot enough to take skin from the bone through. Over the summer, with a heat index of 106, the a/c running max, and hours long stints of 80 mph or more, my gauge ran close to where yours is in the pic. I don’t always put a lot of faith in electric gauges. For me, it’s just a reference to how my car normally behaves.
     
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    • Ian McCrimmon

      Ian McCrimmon Well-Known Member

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      On the road trip this is right about where we pull over and refill the rad!
       
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      • Dana67Dart

        Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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        Just had to:

        Screenshot_20211126-124029.png


        I would assume that thermostat temp would be to the right side of the normal range. Like the same position it is now but mirrored about the center of the gauge.

        IMG_2607~2.jpg

        My 67 dart has the origional temp gauge
        IMG_20200607_152205~2.jpg
        (later they changed the normal range)
        Screenshot_20211126-124330.png


        185 deg thermostat
        June (Colorado)
        IMG_20200607_152205.jpg


        March (Colorado)
        IMG_20200301_130756.jpg


        Ideling in the driveway September (Colorado)
        20190902_153015.jpg 20190902_153003.jpg
         
        Last edited: Nov 26, 2021
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        • Demonic

          Demonic Well-Known Member

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          For that gauge in the top photo with a span from 120 to 250, about 185 is straight up. So I would not worry about running where yours is with that thermostat. My rule of thumb for unknown radiators, and for that matter, block jackets as well - they're dirtier than you think if you have not extensively flushed them with something strong like Thermocure ( easy )or muratic acid ( which takes a bit of skill. )

          You could drain a bit of coolant and temporarily swap to a 180 'stat, see if it runs in the center.
           
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          • Garrett Ellison

            Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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            upload_2021-11-26_15-3-20.png
            Pimpin!
            :rofl::rofl::rofl: :thankyou:
             
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            • cruiser

              cruiser Well-Known Member

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              What is Thermocure?
               
            • Oldmanmopar

              Oldmanmopar Going left turning right FABO Gold Member

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              mages?q=tbn:ANd9GcQBmqVBJNkClXJj-iwWjXiEqkS9RT6GAYjnT6S7-QTFK3SlLTGay-Z_a-gnAjtEXRf8CA8&usqp=CAU.jpg
               
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              • rustycowll69

                rustycowll69 Well-Known Member

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                FWIW, I've flushed my block and rad with different brands of coolant system flush, and what worked best, other than hot tanking a bare block or having the rad professionally rodded-out, is popping some left side soft plugs out of the block, and using a coat hanger or welding rod, and a garden hose with a focused stream of water, rake and flush the water jackets repeatedly until all the rust and sediment is flushed out.
                 
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                • mrhp

                  mrhp Well-Known Member

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                  Side story: When I was a tech at a FORD dealership in the mid eighties, all the new T-birds had a problem with the factory temp gauge reading too high. FORD had no recommended fix. The shop Foreman came up with one. We wired in a tiny inline 'hidden' resistor (I forget what rating) that brought the needle into the correct range. Think of it as an IVR correction.
                   
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                  • krazykuda

                    krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                    Still Hot.jpg
                     
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                    • krazykuda

                      krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                      • Ottmundr

                        Ottmundr 68 Fastback

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                        • pishta

                          pishta I know I'm right....

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                          Was that old valiant speedo pegged? Must have been going downhill with 40 foot lane stripes! The hotter your motor runs within its range the better it operates. you may lose a little power running it hot but mine always seemed to run better....right before I lost a lower rad hose. Then it ran really good for about 30 seconds without the water pump drag! between 160 and 200, the OHM value is about 20 per 10F so if your Ford was running 10F under the guage, splice in a 20 OHM resistor. The lower your temp is the larger the range between 10F OHM measurements. On a graph it would be like this GM graph
                          146806d1194826216-ohming-out-coolant-temp-tempse1.gif
                           
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                          • Cliff Ramsdell

                            Cliff Ramsdell I'm just a guy.

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                            Mid July, 90 degree day, stuck in traffic.

                            Not happy but didn’t blow its top.

                            Cliff Ramsdell
                            3B168D96-A741-4212-BE59-7AAC0438651E.jpeg
                             
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                            • Dana67Dart

                              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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                              Been there too. Sitting in traffic with a pinhole leak in the rad. Also did not boil over so I expect it was not too hot.
                               
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                              • Garrett Ellison

                                Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                                Still within the normal operating range. As mentioned prior, a mechanical temperature gauge is is always good to see what it’s actually running. I myself have not experienced any boil overs until a properly working factory gauge gets almost to full hot.
                                 
                                Last edited: Nov 27, 2021
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                                • clementine

                                  clementine Flight risk FABO Gold Member

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                                  Get one of those $30 infrared temp gun deals. Then take temp at thermostat, rad, exhaust manifold etc etc. I think somewhere on here someone posted some 'norms' of what those temps should be. Thats what Id do if I was questioning the accuracy of the gauge.

                                  $0.02
                                   
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                                  • Ian McCrimmon

                                    Ian McCrimmon Well-Known Member

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                                    Ha no wasn't pegged! On this trip the speedo started out about 20mph to low then after 90 minutes it started to howl and wrapped around to that point!
                                    I just unhooked the cable for the rest of the trip. That video was about 80 km/hr as per my cell phone app. Any higher in the revs and it would heat up quicker.
                                     
                                  • harrisonm

                                    harrisonm Well-Known Member

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                                    You beat me to it. EVERYBODY should have one of those in their tool box. I used to be really worried about the temp gauge on my car (69 340 at about 375 HP with Griffin aluminum radiator) going about 80% up on a hot day, until I used my infrared temp gun and it was only 205. That may sound like a lot, but it isn't too bad. I can live with 205 in traffic on a HOT day with the AC going. I see in this forum all the time where guys say their car never gets above 180. That would be great, but I don't see it ever happening with my car.
                                     
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                                    • Garrett Ellison

                                      Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                                      220 or less when idling in hot weather and I’ve got no complaints. I’ve seen several engines hold 230 while towing for extended periods and never have the first problem.
                                       
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                                      • jos51700

                                        jos51700 Green Bearing thread connoisseur

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                                        Lemme get this straight....you want to know what your 50-ish year old, never calibrated even when new, temperature gauge should read?

                                        :realcrazy:
                                         
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                                        • Demonic

                                          Demonic Well-Known Member

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                                          • Demonic

                                            Demonic Well-Known Member

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                                            Actually, I've found that the factory gauges are usually very, very close on cars that are in fair condition. They're temperature compensated by design, and Chrysler was a company of engineers back then. Some factory gauges actually have provisions to calibrate them, if you disassemble the gauge that is.
                                             
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                                            • jos51700

                                              jos51700 Green Bearing thread connoisseur

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                                              I don't disagree, but there be a huge if in that statement.
                                              Nevermind that there is no scale in the guage, either
                                               
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