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Cooling Issues

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  • Cooling Issues

    I have always fought my Chevelle with cooling issues and never really had a chance to completely sort it out properly. I am looking to really drive my car further distances than I have in the past. I have always just drove my car on cooler days or not very far when it is hot out. It tends to stay around 195 when cruising but as soon as I start slowing or get stopped for any period of time it starts to heat up. Not quickly but faster than I think is acceptable. If I leave it alone and let it idle it will go to 220 no problem. It will get hot if I am running it pretty hard or do a real good burn out.

    Some of the cool things that go in here in Indy aren't exactly close to my house. And I really want to drive my car to some of the events this summer but don't want to stress out about it overheating or have to stop every 10 miles. My car is a 67 chevelle with a 454 HO crate motor.

    8.75:1 compression
    .510 intake .540 exhaust lift
    211 intake, 230 exhaust duration
    112 ATDC and BTDC
    1.7 rockers

    750 vac secondaries Holley
    Hooker comp headers with 2.5 inch exhaust with flows with turndowns at the rear axle with an h pipe

    I am running a weiand team g water pump (mechanical)
    Griffin aluminum radiator with (2) 11" Spal fans (no shroud) that are set to run continuously

    MSD ignition

    The transmission is a TH400 with a 3500 stall.
    rear gears are 4.10 in a 12 bolt
    rear tires are 245 60 15

    I need to check the timing and see where it is at. That is one of the things I think may be causing my problems.

    I think this will be an ongoing thread as I will be addressing seperate issues as I try to hone in on my cooling issues.

    My first question is I have always run 20W50 in all of my older vehicles. Per GM my motor is spec'd to run 5W30 Synthetic. By switching to the 5W30 would that help the motor run cooler? Or is the gain going to be minimal and I need to start by looking at other things first?

  • #2
    First thing is to take some good pictures of the engine bay, from the front, top, and forward from over the engine, so we can see the entire cooling system. Then we can figure out if it's something simple like having a radiator that is way too small (you didn't give dimensions), fans that are way too small or of a bad design (my guess), lousy airflow, etc.

    It sounds like it's a fan problem, since it runs cool on the highway.

    I run 5W30 but I'm weird. I don't run synthetic in big blocks because I haven't figured out how to keep them from using a quart every 1500 miles or less, and it's a waste of money imo to run synthetic.

    195 is fine. 220 is ok. but 10-20 degrees hotter than that is when you need to start to worry.
    My fabulous web page

    "If it don't go, chrome it!" --Stroker McGurk


    • #3
      without a shroud u are only pulling in the 2 11" area of the rad. I would think that leave 40 to 50% of the rad not seeing air at idle or low speeds..
      Drag week 2009 Quickest street rod
      Drag week 2010 Quickest street rod


      • #4
        I would say the gains would be minimal, temperature-wise. I'd still switch, but not expect different temperature readings.

        Originally posted by cal67ss396 View Post
        (2) 11" Spal fans (no shroud) that are set to run continuously
        ^^ This is more of a concern to me. I've never cared for Spal stuff, the CFMs just aren't there. Especially with no shrouding.

        An OEM electric fan with a built in shroud would work wonders I'm betting. I bought one for a HHR that fit nicely on my dual-pass aluminum in the Fox Mustang.

        Last edited by STINEY; May 24, 2013, 12:29 PM.
        Of all the paths you take in life - make sure a few of them are dirt.


        • #5
          What I learned working on newer motors is the computer adds fuel to the mixture to cool the cylinders. If you are running too much timing you will run leaner and hotter, so other than checking and setting your timing at specs, you might want to fatten your air fuel mixture. You might not get the snappy throttle response by retarding the ignition timing, but you will run cooler.

          We went around a few times with shrouds here, to try to draw the heat out of the radiators corners so you arent superheating what is flowing through. Most chevelle owners I know are very happy with their mechanical fan and shroud, do you have room for a mechanical fan if tuning will not lower your temps? Otherwise a shroud will get you at least 10 degrees cooler and out of the danger zone.


          • #6
            Originally posted by anotheridiot View Post
            You might not get the snappy throttle response by retarding the ignition timing, but you will run cooler.
            If the timing is retarded then it will run hot.....

            but I doubt that's the main problem
            My fabulous web page

            "If it don't go, chrome it!" --Stroker McGurk


            • #7
              Clutch Fan
              Electric fans pull really poor CFM


              • #8
                everybody's got an opinion - i am running 1/2 a fill in Florida with dual Spals (14") and it runs on the thermostat (195) all day idleing or blasting down the freeway with the a/c on. However I have a very good shroud and all air that enters the engine compartment goes through the radiator - no other paths available. My radiator is a standard ford (31" x 19") style griffin with 2 1 1/2" tubes single pass. I would work on a shroud and seal it the best you can so that the air has to go through the radiator instead of around it.


                • #9
                  Here are some photos I took of my set up in the past.

                  Looking down obviously.

                  Looking through the grill off to the left is my trans cooler.

                  Here is a concern I have had in the past. The outlet on my water pump is considerably larger than the inlet on my radiator. Hence the reason I have used two hose clamps on my radiator. I know this may not be optimal but like I mentioned previously I have never really had a chance to sort it out completely and now I have the time.

                  Another shot looking down and toward the front.

                  If you look close enough you can see my trans cooler in front of my radiator. Do you guys think this would effect my cooling capabilities.

                  Don't know what if anything this shot shows. Posted it up just because I had it.

                  I will get some better pictures this weekend when I have a chance in the daylight.

                  Thanks for all of your replies.
                  Last edited by cal67ss396; May 24, 2013, 07:39 PM.


                  • #10
                    First question is what thermostat is in it?


                    • #11
                      Forgot to mention it in the beginning.....195


                      • #12
                        First thing I would do is put a colder one in it and see what happens. I would drill a little hole in the plate too.


                        • #13
                          The radiator is borderline too small, the fans are for sure too small, because the radiator is too small.

                          If it were my car I'd start by adding a factory type shroud and a mechanical clutch fan.
                          My fabulous web page

                          "If it don't go, chrome it!" --Stroker McGurk


                          • #14
                            Originally posted by squirrel View Post
                            If the timing is retarded then it will run hot.....

                            but I doubt that's the main problem
                            big blocks are different like that.
                            I was looking for common things..
                            you got nice ignition, nice radiator.. a holley being lean is silly, that would be plenty fat is my guess..

                            I agree with the fan theory. a non-Siamese needs a little guide, hence the mechanical fans. The rest are like lightning up and down, real engines are fluid, the oem fan is a guide.

                            that holds true all the way to small engines, non Siamese bores. they love the mechanical fan.
                            Previously boxer3main
                            the death rate and fairy tales cannot kill the nature left behind.


                            • #15
                              If I am seeing things correctly the fans are set back from the radiator 3/8" - 1/2" so in addition to them not pulling from the entire surface area - they can also pull air from the gap instead of through the radiator. It seems like you could fabricate a shroud pretty easy based on the aluminum strap that you are using to mount the fans. A flat sheet of aluminum sealed with some weatherstrip around the edges of the radiator core might make the difference.