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Thread: Timing settings for a 454 bigblock

  1. #1
    Join Date
    Apr 2018
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    Default Timing settings for a 454 bigblock

    I now have distributor set up so atomic can run the timing but I haven't got a clue what base settings to put in . Running a mild cam tuned 454 7.4 bigblock in my jeep yj to th400 box atlas 2 Dana 60 front 14bolt rear 3.73 gearing
    Can anyone help

  2. #2
    Join Date
    Feb 2018
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    49

    Default

    Basically pick any two digit number that starts with a one.

    Then "you" adjust it up or down from there, according to what the "motor likes".

  3. #3
    Join Date
    Apr 2018
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    I thought I might have had a little more info than that do the msd tech guys reply to messages ?

  4. #4
    Join Date
    Feb 2018
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    49

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    Some times they do.
    But I'm sure this forum is like any other "large manufacturers" forums. They respond when they have "free time".....also known as, when their not answering phone calls.

    Then there's the fact that your question can't be answered too "1 simple number"....this is most likely why your asking if MSD techs come here....you most likely have no experience starting a motor that's been modified.
    So your hesitant with my answer..... Wich by the way is 100% correct.

    If your looking for a education on base timing...it's all theories, that is turned into a "fact", after the motor has been run and "adjusted" to what it likes. Then you have "your" motors base timing.

    If you like. I could ask you about 15 to 30 questions about your motor, fuel, air quality, ignition system. But the answer will be the same that I posted above.

  5. #5
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    Apr 2018
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    So pick a number starting with 1 as you said for total timing doesn't seem correct when others running smallblock and Ford's are running in the 30's

  6. #6
    Join Date
    Feb 2018
    Posts
    49

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    First you asked for "base" timing....thats any number from 10 to 19 at the crankshaft with a timing light.

    Now your asking about "total timing"...that's a little complex. Because for some reason it can be "stated" two different ways. With, or without vacuum advance.

    So. "With out" vacuum advance total timing will be around 30 to 38 degrees.
    This is measured with a timing light, at the crankshaft.
    If you have too much total timing the motor will start to make some funny noises.

    So. In order to find the total timing the motor likes. On a "hot" day, just keep advancing the distributor till the motor starts losing power, or starts to make some funny noises.
    Then you back-off 4 degrees. This is "your" motors total timing.

    To add complexity to the "total timing": The total timing can end at a RPM range of 2400 to 3500 RPM's.
    Why?
    I'll give two examples:
    1. Heavy work truck. Even if this truck had a 500HP motor. It still needs a lot of torque to move. In order to get the "low end torque" the total timing must come in sooner.
    2. Very light Pinto, Vega, Smart Car with a V8. Because it's so light. It doesn't need that much low end torque to move. So you move the torque band up. You do this by putting the total timing at a higher RPM then the heavy truck.

    In between the "base", and "total timing" is what's called the "rate". This is the "speed" at wich the timing changes from the two states. Slower is good for fuel economy, fast rate change is better for performance.
    You just have to "play" with the rate to see what works best...it's actually the hardest part for any one to get right. It's more of how the vehicle feels.

    After all those adjustments. Then comes the easy part.
    The vacuum advance.
    Install a vacuum gauge inline of the distributors vacuum advance. Take the vehicle on a flat Highway. Get it up to a light coasting speed. The object is to get the highest vacuum reading. Most vacuum canisters use a 3/32" allen wrench for adjusting.

    How I adjust a mystery distributor, to a mystery motor:
    1.Plug Vacuum advance.
    2.Put the motor at 10 degrees BTDC.
    3.Install distributor so points/optical/hall sensor triggers coil.
    4.Start motor.
    5.Drive it to find total advance...I just stop on the side of the road about five times adjust it. No timing light needed.
    6.Go back to shop to use timing light to see what the total timing is. Wright it down on air cleaner.
    7.Advance the distributor, and start the motor. Keep doing this till the motor doesn't like to start. Rotate the distributor back a little bit. Use timing light to see what this number is. Wright this number on the air cleaner.

    So. I now have two numbers on the air cleaner. Take the smaller number ( base ) and subtract it from the larger number ( total, with out vacuum advance ). This "new" number is the advance that the distributor should give me.

    8.Start the motor ( leaving the distributor at the good base timing ). Use the timing light to see how far off the "distributors factory mechainical advance" is from the total timing I have written on the air cleaner.
    9.If it's off by 1 or 2 degrees. I'll leave it alone. Higher numbers, then I'll get a "advance kit" for it.
    10.Then I adjust the vacuum advance.
    11.Then I try out both types of vacuum ports for the vacuum advance. Ported, and Full time.
    12.If Full time port works the best ( motor stays cooler ). I'm done.
    13.Ported works the best. Some thing is wrong.

    Note: For number 12 and 13. It is very subjective. With the way I tune. Full time advance has always worked the best for me 80% of the time.
    Last edited by BITE_ME; 04-25-2018 at 11:09 AM.

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