First time overheating my '66 BB!! - NCRS Discussion Boards

First time overheating my '66 BB!!

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  • Steven S.
    Expired
    • August 29, 2007
    • 571

    #16
    Re: First time overheating my '66 BB!!

    Did you fill the radiator to the top? You only need to fill up to the fill line on the rad (approx. 2" or so from the top), filling it to the top would result in it pushing some out after it heats up, otherwise unfortunately I'd say you have some more signifigant problems now.

    Steve

    Comment

    • Nick L.
      Expired
      • May 31, 1998
      • 82

      #17
      Re: First time overheating my '66 BB!!

      The 160 degree thermostat is, IMO, not suitable for your application (especially if you are driving the car in the spring and fall seasons when ambient temps are under 50F).

      Comment

      • Timothy B.
        Extremely Frequent Poster
        • April 30, 1983
        • 5186

        #18
        Re: First time overheating my '66 BB!!

        Andrew,

        Do you recall if the car was overheating when the coolant was overflowing out of the radiator . If not, have your radiator cap pressure tested..

        Comment

        • Andrew S.
          Frequent User
          • July 29, 2009
          • 56

          #19
          Re: First time overheating my '66 BB!!

          It was the temp sending wire -- I reconnected it & it was good to go (at least until Thursday when it's supposed to snow ). It runs at about 160.

          Why is a 160 thermostat a bad idea for running in northerly climates?

          Comment

          • Joe R.
            Extremely Frequent Poster
            • July 31, 1976
            • 4550

            #20
            Re: First time overheating my '66 BB!!

            The thermostat is suppose to open and close as needed to keep an even heat throughout the engine. That's why mechanics don't recommend running without a thermostat.

            In your case the BB will run hotter than 160 all the time so the thermostat will remain open at operating temperature. That would defeat the purpose of the thermostat in the first place.

            Maybe a 180 would be more in line with the desired temperature. Don't think it makes any difference where you live if the thermostat is defeated.
            Maybe Juno Alaska would be different or Santa's' home at the North Pole.

            JR

            Comment

            • Stuart F.
              Expired
              • August 31, 1996
              • 4676

              #21
              Re: First time overheating my '66 BB!!

              I have run a 160* thermostat since my first coolant change back in the mid-60's. My reason was simply because the engine ran better with it. In heavy traffic, when I would get temp creep, it would stumble and hesitate. Only recently, I believe I have finally cured that problem with extensive carb rework to address the fuel situation of today. I believe I could now finally go up to a 180* and would if I still lived up north, but I don't. My reason would be simple: You get a lot more heat out of the heater on cold days. This specially important if you have a convertible top only. Up north, I used to like to drive the early spring and late fall days with the top down and the heater on, and the 160* just wasn't doing it for me.

              Stu Fox

              Comment

              • John H.
                Beyond Control Poster
                • December 1, 1997
                • 16513

                #22
                Re: First time overheating my '66 BB!!

                Originally posted by Andrew Smith (50659)
                Why is a 160 thermostat a bad idea for running in northerly climates?
                Andrew -

                The thermostat does several things:

                1. Remains closed at cold start until the coolant in the engine reaches the thermostat's rated opening temperature, promoting rapid warmup and reduced engine wear.

                2. Modulates the flow of coolant to maintain a constant operating temperature (assuming the cooling system is capable of cooling below the thermostat's rating); this ensures adequate heater/defroster performance in cold weather - coolant will be at the thermostat's rating temperature regardless of ambient air temps. If you run a 160* thermostat in cold weather, the oil in the pan will never get hot enough to boil off blow-by contaminants and condensate moisture - that stuff will just stay in the oil and turn it acidic, which tends to form sludge.



                The thermostat has absolutely nothing to do with controlling above-normal operating temperature - it only controls the minimum operating temperature. For example, if your engine runs at 220* with a 180* thermostat, changing to a 160* thermostat won't affect it at all - it'll still run at 220*. Cooling system performance is a function of the radiator's heat rejection capability ("cooling capacity") and the airflow through it.
                Last edited by John H.; November 29, 2009, 04:58 PM.

                Comment

                • Stuart F.
                  Expired
                  • August 31, 1996
                  • 4676

                  #23
                  Re: First time overheating my '66 BB!!

                  Andrew;

                  What John says is perfectly correct about cooling systems - and he should know. To add to this, I would only say that every car, engine and cooling system operates slightly different from one to another. In my situation, I have an L-76 63 SHP engine, and like many other midyears, it has an aluminum intake manifold. All Chevy V8 engines of the era use a one piece cast Iron or aluminum manifold which also includes the water manifold portion at the front where the thermostat is located. The coolant temperature in the water manifold will at least reach the rated temperature of the thermostat before it begins to open and circulate. Many of these manifolds also have the temperature sensor in the water manifold. As such, assuming your sensor and gauge are functioning properly, you will see an indication of what the coolant temperture is, i.e. if you have a 160* thermostat, when the engine is at normal warm up temperature, it will read 160* - ditto for a 180* thermostat.

                  My theory, from 46-1/2 years with my car, is that some of that heat in the water manifold transfers to the intake portion of the manifold and, in particular, the carburetor and has an effect on the intake mixture.
                  This heat, besides as noticed on the gauge, can also be tracked using an IFR gun to measure at different positions on the manifold. The hot spots seem to be at the front water manifold connections to the heads and at the rear coolant block off portions. Granted, specially with a stock manifold installation, the exhaust cross overs immediately under the carb have an even greater effect on the carb intake mixture.

                  The bottom line is that, with my car, the 160* thermostat seems to have less of an effect on the mixture due to slightly lower manifold temperatures than with a 180*,i.e. it runs better - less hesitation and stumble (at least in the Florida heat).

                  To improve this situation even further, specially with todays gas, I have insulated my carb from the manifold using a phenolic base plate and re-jetted it to suit.

                  As for concerns about reaching hot enough oil temperatures, one good run through the gears to redline will take care of that real quick (if you ever had an oil temp gauge in your car you would know what I mean).

                  Comment

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