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Thread: engine running temp

  1. #1
    Carb and Points!
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    engine running temp

    Thanks to all you young guys, I converted a 1970 455 olds to gm tbi and put in a boat at 75 at years old. I used 89 454 parts with 7747 ecm. My problem is the engine is salt water cooled and and has to .run at 143 degrees. Any higher the salt comes out of the sea water and RAPIDLY collects in the engine. Has anyone dealt this type of issue. It runs fine at 143f. for my needs but not foe the ecm. Could the prom be be changed to see 143l as completly warmed up ? Thanks again steve

  2. #2
    Fuel Injected!
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    Quote Originally Posted by spielco View Post
    Thanks to all you young guys, I converted a 1970 455 olds to gm tbi and put in a boat at 75 at years old. I used 89 454 parts with 7747 ecm. My problem is the engine is salt water cooled and and has to .run at 143 degrees. Any higher the salt comes out of the sea water and RAPIDLY collects in the engine. Has anyone dealt this type of issue. It runs fine at 143f. for my needs but not foe the ecm. Could the prom be be changed to see 143l as completly warmed up ? Thanks again steve

    What is it doing? You should just have to change the temp based scalers. Ones that increase timing for temp, AFR for temp, and engine RPM for temp.

  3. #3
    LT1 specialist steveo's Avatar
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    i know this isn't the question, but why not find yourself a nice big heat exchanger and get a proper closed loop system going for your engine so you can run a proper operating temp? a big ol' iron engine like that really needs to get a bit hotter to run its best

  4. #4
    Fuel Injected!
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    Quote Originally Posted by steveo View Post
    i know this isn't the question, but why not find yourself a nice big heat exchanger and get a proper closed loop system going for your engine so you can run a proper operating temp? a big ol' iron engine like that really needs to get a bit hotter to run its best
    Actually they do not! The modern 350 Mag MPI and 496 Magnum HO use a 120°F thermostat and runs under 140°F.

  5. #5
    Carb and Points!
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    I forgot to mention this a berkeley jet drive package that was salt water cooled. I need to satisfy the ecm as 143f is not hot enough. steve

  6. #6
    Fuel Injected!
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    Quote Originally Posted by spielco View Post
    I forgot to mention this a berkeley jet drive package that was salt water cooled. I need to satisfy the ecm as 143f is not hot enough. steve
    There is really not much to altering the tables to make it work with that operating temperature.

    There is a coolant temperature based spark modifier table.

    There is also a coolant temperature based air/fuel ratio table.

    There is also an coolant temperature based idle speed table.

    One merely need to adjust those tables to make the value slightly lower than the normal operating temperature the same values as the normal 190-210*F of a road going vehicle. That means you are not adding additional fuel or timing for the cold engine and the idle speed is set to where your application requires.

    I am assuming you are running without an 02 sensor in the manifold. You should be able to use a 7747 leaded fuel .bin for an early year model 454 as a good starting point as they ran entirely in open loop and also ran without a knock sensor.

  7. #7
    Carb and Points!
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    It does have 02 sensor I put a 02 sensor right in the exhaust manifold at the rear exhaust port. By putting 400 ohms across the coolant sensor, when its at 143f the scanner said 178f. Do you think this will fly. It does have knock sensor. Its starts fine and because its a boat, winter cold starts won t be an issue. steve

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