455 running too warm

Discussion in 'Street/strip 400/430/455' started by dfish1247, May 12, 2018.

  1. dfish1247

    dfish1247 Active Member

    Wednsday, I brought home a 1964 skylark 455/400/3.08 10 bolt posi. Car runs great btw.

    However, when driving down the interstate, it was mid 80's outside and running 60mph, car ran 210 temp, I tried 70mph, but car got up to 220 and I backed down to 60mph, temp went back down to 210 and would stay there, never budged. Idling in stuck traffic, would take a bit but the temp would come down to 200. In town, runs 200 at most. Engine is nothing unruly, runs on premium, no pinging, makes 16" vacuum at 500 rpm idle.

    Car has aluminum radiator(3 or 4 core, pretty thick), completely covers the opening in the core support opening as well, electric fans in an aluminum shroud, 195 tstat, mechanical water pump. There is an ac condenser and trans cooler stacked in front of the radiator, nothing is blocked as fas as airflow. I have run the ac some, not long enough to know any effects though.

    I haven't checked hoses to see if the suction side is collapsing, but I don't think it is because the car doesn't overheat nor puke. I'll check that plus the radiator itself for cool spots(plugged). I'm going to change to a 180 tstat, but that won't help the interstate cruising. My guess is the water pump isn't up to the task.

    Thanks in advance.
     

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  2. CJay

    CJay Supercar owner Staff Member

    A 195 stat starts to open at 195. Its normal for a car with a 195 stat to run about 10 degrees above the opening temp. So 205-210 sounds about right. Hotter the better. And for the record, 220 isn't hot. Runner your engine cooler increases ring wear and doesn't allow the oil to get hot enough to burn off the contaminants and moisture. I run my race car around 205-210
     
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  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    As stated, the engine won’t run any cooler than the thermostat will let it. A 195 stat starts to open at 195 and isn’t fully open until 215. The only concerns I have about running up around 210 is detonation and oil temperatures. As long as your oil pressures are good and you hear no detonation, you can run that warm. Having said that, I think the best all around temperature for an older performance engine is 180*. I don’t buy the claims that it isn’t hot enough to drive off the water and contaminates unless you are doing lots of short trip driving, and that goes for any engine. Newer engines with microprocessor controlled everything and knock sensors can run high temperatures with no problem, but our Buick engines running on cat piss E10 can have issues if the mixtures get a little lean and timing a bit aggressive.
     
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  4. dfish1247

    dfish1247 Active Member

    It doesn't detonate or ping, oil pressure runs around 50 psi running and around 12psi at idle. I've got a 180 and 160 thermostat. going to try the 180 first and see what happens. Obviously I've got a deficiency somewhere because the thermostat is staying wide open other than putting around town. I feel the timing is set conservatively because it doesn't ping and the starter doesn't have any trouble turning the engine over, it seems as if i could put a pull rope on it and start it, if that tells you how easy it turns over.
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    You should actually put a timing light on it and see what the timing is at your cruise RPM. Make sure that the vacuum advance is actually working. To run the coolest, you want the timing to be up around 40* or so at light load cruise.

    You mentioned that the radiator was aluminum, and you thought it was 3 or 4 core. If it has any more than 2 rows, it uses smaller tubes, which completely negates the reason for aluminum in the first place. Aluminum is stiffer, and it can support tube sizes up to 1 1/2”. 2 rows is all you need with tubes that big. A 3 or 4 core aluminum radiator would have 5/8” tubes, and would actually be inferior to an identical radiator of brass/copper construction. Brass/copper conducts heat better than aluminum. Open your cap and see how many rows you actually have. The best aluminum radiators have 1 or 2 rows max.
     
  6. Schurkey

    Schurkey Silver Level contributor

    1. What temperature do the fan(s) turn ON?
    2. What temperature do the fan(s) turn OFF?
    3. How much of the rad is blocked by the shroud? Is the shroud vented with closeable louvers that can let heat out at high vehicle speed, but close at low speed?
     
  7. dfish1247

    dfish1247 Active Member

    The fans kick on at 190 and never cutoff, due to the 195 stat. The rad is completely blocked other than the fan openings, there are no louvers. I was wondering if that would help, or even try just pinning the fans to the radiator. With the shroud barley being 1" thick, I would think there is some terrible turbulence and dead space. That would be free to try first.

    If I run out of things to check and am left with a water pump replacement as my next step, are the flowkooler and/or TA pumps of any benefit? I really don't want to try and use an electric if I don't have to.
     
  8. Eric

    Eric Founders Club Member

    Listen to Larry... many years ago he helped me get my temperature down from 210 down to 170-180 and it purrs like a kitten ever since.
    Eric / Oregon
     
    Last edited: May 28, 2018
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  9. Stevem

    Stevem Well-Known Member

    A rad needs to have the area & flow capacity for highway driving to hold the temp at 5 degrees above whatever the stat it you have in it!
    If the engine has a bad fan clutch , then at highway speeds the fact that it does not declutch will block off air flow and it will not matter if you have two 4 row radiators in the nose of the car it's gonna run hot!!
     
  10. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    If it's quick and easy I'd pull the shroud and hop back on the highway. Obviously this is not a long-term solution but it ought to provide you with some data. If it runs cool then you know the shroud is restricting the air flow. 180 stat is what i would run aswell.
     
  11. shiftbyear

    shiftbyear Well-Known Member

    Sometime a pulley change is required to make the water pump spin faster. Changing to a different diameter pulley may put you in a better temp range.
     
  12. 87GN_70GS

    87GN_70GS Well-Known Member

    A thermostat's rated temp is the temp the cooling system is designed to run at, given sufficient cooling capacity. Don't believe this? Take your vehicle out on a freeziing winter day and read what your temp gauge is telling you. It will be the number stamped on the box.
     
  13. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    Yeah if you boil them on the stove they creep open at the rated temp but they will be wide open at rated temp.
    As the water cools back to the rated temp the thermostat is wide open until it drops below.

    A lot of folks think it's barely open at the rated temp.
     
  14. dfish1247

    dfish1247 Active Member

    Haven't tried anything yet, no hoses are collapsed, and it is in fact a 2 core rad, my bad on the description. I ran around in town on some errands with the AC on and the most I saw was 205 (90+ degrees outside.) I figured the AC would be some extra load on the system but it doesn't seem to hurt anything. I'm hoping tomorrow to get the 180 installed and pluck the fan shroud then go for a drive and see what happens, i say hoping because the 700r4 in my truck destroyed itself and have to find someone to replace that.
     
  15. dfish1247

    dfish1247 Active Member

    Guys I’m so sorry about being this late on the pics, been raining and I’ve worked 12 of the last 14 days.

    As you can see, the shroud is solid except for the fan openings. Couldn’t tell how many rows of tubes though due to being full, which is a good thing.

    Something that did strike me odd is I squeezed the lower radiator hose and I could feel the spring but it seems the rubber gives a little( very little)in between the spring, could the hose be collapsing somewhat and starving the pump? All that braided hose is just mr gasket braid cover btw. Previous owner installed it.
     

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  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I thought you said it was a 2 core radiator, 2 core means 2 rows of tubes. Did you put in the 180* stat? The lower hose is not an issue. I'm not a big fan (no pun intended:D) of electric fans. A stock shroud and good clutch fan is all it takes IMHO.
     
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  17. TORQUED455

    TORQUED455 Well-Known Member

    All radiators have 1 core, 2 tanks and varying amount of rows. Stock fan, fan clutch and a good aluminum radiator is all that’s needed, along with a 180 stat IMO. Now finding a good, aluminum radiator that fits is the only semi-difficult task. There is a lot of Chineseum out there.
     
  18. TORQUED455

    TORQUED455 Well-Known Member

    For the life of me, I can’t understand the amount of “my car runs hot” threads. My street car, 72 GS convertible with a 455, ran 160-165 degrees on a 70 mile cruise yesterday, 85 degrees out, in combined highway and stop and go driving. Runs 10’s at the track with a Qjet and 11:1 compression, 3.42 gears and ran 2800-3000 rpm on the highway, with a Coan 4000 converter. Stock fan and fan clutch, 160 thermostat, 50-50 mix and a plastic tank, aluminum core radiator out of a 90’s GM product. We went to the iconic Rudy’s Fish Fry up on Lake Ontario for a fish sandwich.
     

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  19. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I don’t get it either Bob, I use a 180 stat, and my engine runs right at 180 even in stop and go traffic yesterday. I have the same Griffin 2 row radiator since 2000, so I know it will eventually need to be replaced. Exactly what radiator are you using? Is it one row or two?
     
  20. Electra Bob

    Electra Bob Well-Known Member

    Been following this thread with interest.

    Since I got a temp gauge in the Electra I now know that in 90* ambient and stop-start driving it's maintaining close to a peak of 220* Cruising speed it will run at ~200*

    Oil pressure when this hot is still a steady 20 psi at idle and 40-50 psi when moving so I'm not too concerned but I get the notion it might be happier to run somewhat lower. I know I'd feel happier :)

    All stock cooling components with no A/C. This is a sunny day, cruise night, feel good driver car.

    If I were to go with a 160* thermostat what would be a good brand? There are an overwhelming number out there and I don't want to get screwed by fitting a shiny new but junk unit.

    Any other comments/suggestion welcome.

    Cheers!
    Bob
     

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