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Please help me cool my 460!

Discussion in 'The Hokey Ass Message Board' started by JayD, Jul 3, 2012.

  1. 58custom
    Joined: Jan 1, 2009
    Posts: 398


    Being that the issue occurs when cruising and not idling I do not believe that fans will help. You alread have positive air pressure at the front of the radiator.

    One other place to look at is how easy it is for the hot air to get out of the engine compartment. This thing lowered?
  2. Vandy
    Joined: Nov 15, 2009
    Posts: 368

    from L.A. Ca

    Please before you post this type of info, head over to the 460 web site & learn more about the 460. I have ran 460's for many years and know them well & have 2 D9 (79 & later)truck blocks bored to 4.500 most any will easily go to 4,440 which is .080 over std. If you have a 460 that sonic checks "super thin" at .030 over, you sir most likely have the only one ever made.
    Last edited: Jul 3, 2012
  3. trollst
    Joined: Jan 27, 2012
    Posts: 1,791


    Different take here, how do you know its running hot and not the guage? Where is the sending unit? In the head, or intake? If its in the head, it'll show exhaust temps when the engine is working, but low temps at idle, cause there's no exhaust heat there, Do you trust the guage? Before spending a wad, check the things you'd never think to check, its probably something simple, look at the electric fans, how much airflow do they block, the front of the rad should be clean space without a bunch of crap in the way of the air coming in. A 160 thermostat will open wide at any temp over 160, not slowing flow, like it should, stay with at least a 180, really sounds like you have an air flow issue to me.
  4. wide34
    Joined: Mar 2, 2006
    Posts: 476

    from Texas

    Someone else already mentioned it but make sure you have a good backing plate for the water pump. Most pumps I'm aware of do not include the backing plate and many old backing plates are eroded through. If the gauges are accurate I'd bet you have problems with the backing plate either missing or corroded. Hope you find the problem, the 460's are great engines!
  5. kye
    Joined: Jul 2, 2012
    Posts: 8


    The head gasket part scares the hell out of me.There's only one way to be sure...
    how do you know its not hot at the lower speeds.could your water velocity be low enough to not register the truth at the temp sensor?
    Run with the heater on too, and get feed back from that. Does the heater core match the temp guage?
  6. fourspd340
    Joined: Feb 23, 2009
    Posts: 45


    Before you get too crazy, I would like to see a picture of the radiator, shroud, and fan, and the relationship that they are all placed in. Believe it or not, it makes a BIG difference in the spacing. I went through this a few years ago and now I am cooling my 600 HP Hemi with a copper radiator, stock shroud, and stock mechanical fan.

  7. BuiltFerComfort
    Joined: Jan 24, 2007
    Posts: 1,620


    What is the path of air to the radiator when at speed? Is there a way for air to bypass the radiator? The sheet metal behind the grill should funnel all air through the radiator.
  8. Gator
    Joined: Dec 29, 2005
    Posts: 4,016


    True, but a 'copper' radiator is not made up of just copper - brass tubes connected to the tanks with lead/tin solder, which reduces the efficiency somewhat. There's also the overall design to consider - aluminum radiators have wide tubes and smaller cross sections, need less velocity to achieve optimum thermal transfer and thus provide improved cooling.

    Me too Don - I've got aluminum radiators in both my '55 Chevy pickup and my 472 equipped '55 Cadillac. Both run cool even in stop & go traffic WITH the AC on.

    BUT there's more to cooling a car than just the radiator, and I think the 'sum of the parts' is more important than what the radiator is made of. IMHO you need;

    Correctly sized fan
    Proper fan shroud
    Overflow/coolant recovery tank
    Working T/stat
    Properly adjusted belts on correctly sized pulleys;
    etc etc.

    And as others have mentioned timing, tuning and fuel mixture.

    OT cars, but I worked at a Pontiac / GMC dealership years ago - we had a rash of Firebirds and Trans Ams with overheating problems, but only at highway speeds. We finally discovered the culprit was damaged or missing air dams. Without the air dams not enough air was being forced thru the radiator at speed.

    Another misconception is that anti-freeze or a 50% mix cools better. Water alone has twice the heat transfer capability when compared to 50% glycol antifreeze/coolant in water. BUT anti-freeze ads lubricating and anti-corrosive properties, as well as raising the boiling point of water.

    Here's a link to some good technical info:

    Thermal properties of cooling system materials
  9. ....That's the whole idea !!! idle with full manifold vacuum advance it will have LESS of a tendency to rpms come up your mechanical advance comes in to keep the timing from retarding too much...running too retarded causes the engine to run hot.....full vacuum advance at idle will certainly help run cooler.
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 46,889


    It's almost as if the factory engineers knew what they were doing....
  11. Damn Yankee
    Joined: Aug 6, 2006
    Posts: 28

    Damn Yankee

    This may sound crazy to you gentlemen, but my dad ran his own repair business, back when that 460 was a popular engine. he and I chased a similar problem, overheating at h-way speed only. we found the water pump impeller was slipping on the shaft. if and when you pull off the pump to check for the proper plate, you might want to hold the shaft and try to spin that impeller. funny how you don't forget something like that. Happy Fourth everyone John
  12. I bought a new 460 in '87. Went through 3 water pumps in 4 years.
  13. My SBC runs cool at 60-70, but will start to run hotter at 75-85MPH when the RPMs are up like that. I'd do the gear swap regardless 3K to do 70 is too much.
  14. if I remmember right the 460 have a Water Distrabution Tube
    in each Clynder head which and if they Rot out
    you Have Overheating Problems
    I know on my 460 ( 71 ) they have them
    just my 3.5 cents
  15. Vandy
    Joined: Nov 15, 2009
    Posts: 368

    from L.A. Ca

    Water distrabution (distribution) tube ???? . Did your 71 have muffler bearings ?
    Last edited: Jul 4, 2012
  16. bohica2xo
    Joined: Mar 6, 2012
    Posts: 153

    from Las Vegas

    Pull the cap off of the distributor, and make sure the mechanical advance works. Rotate the rotor, it should move 10 degrees or more.

    Lots of vehicles have slipped dampers, mismatched covers & dampers, etc. Here is how you get past that.

    1) Disconnect the vacuum advance & connect a vacuum gauge to the manifold.
    On a warm engine, adjust the timing for highest idle vacuum on the gauge, and tighten the distributor clamp.

    Go for a test drive. Leave the vacuum advance disconnected. Make a couple of WOT passes. If you have a C6, start in 2nd & load the engine down. If it pings, you need to limit the mechanical advance. If it does not ping, try a lighter spring set if you can. If lighter springs make it ping... go back one step.

    2) Connect the vacuum advance to Manifold Vacuum. Go for a test drive. Varying loads & speeds. If you have pinging, adjust the vacuum advance. Adjust it to add advance if it still seems sluggish, or rough. The object is maximum advance at part throttle cruise.

    Once you go through those steps, you will have maximum advance for idle, cruise & WOT. Whatever the marks say. I have a 302 that is happy with 50 degrees total at cruise.

    I have had several 460's. They will run hot if retarded. This includes overheated exhaust manifolds (with cracking). I had a '73 LTD Wagon that broke two manifolds while still under warranty. All because of the stupid smog timing. It had about 24 degrees total IF the stars aligned and that forest of vacuum switches let the vacuum get to the distributor.

    Time it up.

  17. Vandy yes they do have Stainless Steel Muffler Bearings!
    and Gold Plated Blinker Fluid & dual Exhaust
    Hydralic Windshield Wiper's

    what else would like to know???

    just my 3.5 cents
  18. JayD
    Joined: Aug 29, 2005
    Posts: 544


    Update.....pulled the heads, gaskets OK, new gaskets, 160 degree thermostat, moved the tranny cooler (air went through the cooler, through the A/C condenser, then the radiator). Now running 210 on the highway. Gonna install 180 thermostat and see if that does the job.

    Thanks for all the good help and suggestions!


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