Timing retard

Discussion in 'Electrical and Ignition' started by mopowers, Mar 20, 2017.

  1. mopowers

    mopowers Well-Known Member

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    Is it true that Standard Mopar orange boxes pull out timing under high load? What about standard parts store 4-pin HEI modules?
     
  2. ktcnn94

    ktcnn94 Well-Known Member

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    :popcorn: I'm curious also. I've heard this but unfortunately have not researched it. Maybe trailbeast with chime in, he's probably up on it.
     
  3. Mark2205

    Mark2205 Well-Known Member

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    No, I don't think the orange box pulls timing out under load. It doesn't know whether your engine is under load or not. The only input it gets is from the reluctor wheel in your distributor. Now i have seen the initial timing will change between boxes.
     
    Last edited: Mar 20, 2017
  4. KitCarlson

    KitCarlson Well-Known Member

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    That is done in a way, by the vacuum advance. Under full load vacuum drops to near zero, so no advance. Under light load, high vacuum so more advance. Closed throttle drops vacuum, under coast, and idle that is good thing.

    Ignitions with micro controller and MAP/vacuum sensing port, typically control timing with load, but usually with user configurable tables. No micro in orange box, nor a way to sense load.
     
  5. mopowers

    mopowers Well-Known Member

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    I called FBO today and ordered one of his limiter plates for my dad's 360 and he was telling me that the orange mopar ECUs and parts store HEI modules pull timing out in high load situations due to them being tranisterized. That kinda stuff is over my head, so I figured I'd see if there's any truth to it.
     
  6. KitCarlson

    KitCarlson Well-Known Member

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    I have heard the term :"pull out dwell", associated with FOB ignition. But like nearly any single coil ignition, at high RPM, dwell time decreases.
     
  7. mopowers

    mopowers Well-Known Member

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    I was aware of that as well. But when Don at FBO specifically told me that all transistorized ignitions retard timing during high load, it got me wondering. I thought all ignition control boxes were basically just a switch telling the coil when to fire. How would it know when the engine is under load? I realize Don is in the business to sell ignition boxes, but is there any truth to his claims?
     
  8. crackedback

    crackedback FABO Gold Member FABO Gold Member

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    Simple answer is Yes, they have been known to pull timing at higher Rpm.
     
  9. KitCarlson

    KitCarlson Well-Known Member

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    How much is pulled?
     
  10. mopowers

    mopowers Well-Known Member

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    According to the gentleman at FBO, 6-8 for a mopar orange box and 4-5 for a parts store HEI module.
     
  11. AJ/FormS

    AJ/FormS FormulaS clone 367-3.55s 3.09-1.92-1.40-1.09-.78od

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    Does it really matter on the street? I mean a stout 360 can smoke the tires to 50/60 mph anyway, no matter what the timing as long as it's close. And a lot of guys put too much timing in their combos anyway.
    Now if you pulled timing early on a 273, I could see that being a problem.
    I've had two Orange boxes, and neither had pulled timing by 5000.
    I've heard it said that racers might pull timing up there to increase their trap speed.I don't know if there is any truth to that, but I do know that MSD sells timing retard boxes.lol.
    If the orange box does retard the timing after say 5500/6000, would that be a bad thing? And you would be getting that feature included, no extra charge.
    IDK, just rambling.......
     
  12. Mattax

    Mattax Just the facts, ma'am

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    The electronics slew rate makes it seem like retard.
    drag race engine ignition systems • Speed Talk
    Mopar Performance had very good reason for setting up the 'tach drive' race distributors with that big secondary spring. Very effective mechanical solution. There are now some electronic systems that essentially claim to compensate.
     
  13. KitCarlson

    KitCarlson Well-Known Member

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    The turn off delay of a modern IGBT coil driver is about 3000 nano seconds, at 6,000 RPM, that equates to about 0.1 degree retard. There is also a small amount of logic delay, typically less than 0.1 degree. The thing about electronic advance, the curve can be controlled, including folding back, as desired, not limited by mechanical weights, springs ....

    Yeah, the Mopar electronic distributors and boxes are 70's era, and compared to modern devices .....