Timing of plugs firing

Discussion in 'Engine, Fuel and Exhaust' started by bigbubba402, May 19, 2011.

  1. bigbubba402

    bigbubba402 Active Member

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    Ok so I have started my change over to roller cams this evening.All of my timing marks line up good everything is going together good.Here is my question/concern I have rolled the engine over several times getting ready to install new push rods got to thinking (I know that is my problem) Lol.How do I know that the plugs will fire on compression or exhaust I could have everything out 180 degrees unless the plugs fire every rotation compression and exhaust is this correct or is it possible that the plugs will fire 180 out.I am comparing this to a distributor maybe that is my problem.Hopefully I am concerned about nothing Thanks Bubba
     
  2. 2006FXDCI

    2006FXDCI Active Member

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    Both valves will be closed on the compression stroke.
     
  3. bigbubba402

    bigbubba402 Active Member

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    2006fxdci,
    Yes that is correct but is it possible to have that 180 from when the plugs fire?Or do they fire on every rotation?
     
  4. TripleJ

    TripleJ Senior Member

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    As long as you lined up the timing marks prior to pulling the original cams and the marks were lined up correctly when you installed the new cams you will be ok.
     
  5. R_W_B

    R_W_B Senior Member

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    Correct, in other words you won't have any pressure on the pushrods or lifters the valves will be totally shut.

    TripleJ has you covered on the answer to that but in the old days they did fire every rotation. The wasted one was on the exhaust and intake strokes
     
  6. bigbubba402

    bigbubba402 Active Member

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    Ok thanks will finish it up tomorrow
     
  7. Hoople

    Hoople Account Removed

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    The cam sensor is responsible for phasing the ignition system. It only allows the ignition to fire on TDC of compression. I am pretty sure you have a cam sensor on a 2002.
    (at least according to the DTC code list you do:))
     
  8. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    There is no timing until you install the timing gears. As TrippleJ said above, as long as you line up all the timing marks, that establishes the timing.

    TQ
     
  9. R_W_B

    R_W_B Senior Member

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    I know exactly how you feel bigbubba, you get so preoccupied with trying to cover all the bases you over think it sometimes. It's great to have precise answers like Hoople's, TQuentin's etc to help you along. I've never done what you are doing but after reading their replies I remembered assembling lawnmower engines and the cams had little painted marks on each gear to line up. And of course the ignition is all electronic design now days.

    When I first read your post I thought maybe you were wanting to adjust the pushrods or lifters.

    Tell you what though, I would enjoy reading about each step you did when you get done. Even if you didn't take any pictures, just a step by step process in your own words would be something I would like to read if you have time.
     
  10. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    In the mean time, check this out:

    TQ's Engine Build

    TQ's Engine Build - Harley Davidson Community

    TQ