Initial timing settings

Electrical and Ignition

  1. swies

    swies Wish I had more time.

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    I have been scrubbing the posts trying to find some answers to timing.
    I have an Eddy 1405 sitting on my Performer RMP AG sitting on my mild 1975 318.
    The Carb has 2 vac ports on the base. One is 'Timed' and the other is 'Manifold'.
    Which one should my advance can be attached to???
    When setting the initial timing, should the vac advance be disconnected?
    I see in other posts that my initial should end up in the 8*-12* range and that SHOULD put my total at 36ish.
    Does that all seem correct? or did I miss something crucial?
    Thanks to all of you for the great help.
     
  2. TrailBeast

    TrailBeast AKA Mopars4us on Youtube

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    A ton of reading up on Vac advance and why would be a good thing.
    Manifold vac is in full advance at idle and ported is for zero advance at idle.
    They are two completely different functions for different reasons.
    Ported came about to make engines run hotter for emissions at lower/idle RPM's
    Manifold gives full vac advance at idle and backs it down as engine load goes up via throttle plates opening and lessening the amount of available vacuum.

    With a stock style distributor I think you'll find that setting it at 8-12 initial you will end up needing to limit the mechanical advance so you don't end up with way too much total between initial and mechanical (which is a normal thing to do)

    I recently found a good writeup on it and I'll see if I can find it for you.

    This one is a good one to start with.
    http://www.hotrod.com/how-to/engine/mopp-0301-mopar-electronic-ignition-system/
     
  3. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    While TB and I agree on ported vacuum, the problem is that there are "two schools of thought." Some advocate using FULL vacuum, and IF YOU DO THAT you will need a completely different mechanical curve.

    With the way 'we' think, IE ported, timed, no idle vacuum.....

    8-12 initial is nowhere near enough.......

    you definately want vacuum disconnected at idle

    if you go to the Edelbrock site, there are downloads of manuals for the carbs which tell you all you can imagine about them

    There has been TONS written on this site about timing.

    Here's one

    http://www.forabodiesonly.com/mopar/showthread.php?t=158842

    and

    http://www.forabodiesonly.com/mopar/showthread.php?t=150251

    One thing you need to keep in mind. All factory distributors 69 / later are "smog" advance curves, not what you want for performance, and they get worse up into the mid 70's. "Long slow" advance curves as opposed to "fast and short"

    This means you either need to replace the smog factory distributor with an adjustable aftermarket one, or else recurve the one you have
     
  4. abodyjoe

    abodyjoe Well-Known Member

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    • TrailBeast

      TrailBeast AKA Mopars4us on Youtube

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      Thank you.
      That's the one I was looking for, but it's on my home computer and I'm not at home. :D
       
    • swies

      swies Wish I had more time.

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      Great Reading!.
      I forgot to mention I already have an ACCELL distributor on it.
      I do not have a vac gauge so I will have to wait for a payday to make that happen.
      Thanks so much for the help!
       
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