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Installing Delco Petronix

Discussion in 'Early CJ5 and CJ6 Tech' started by Randy Benedict, Jan 10, 2021.

  1. Jan 13, 2021
    Randy Benedict

    Randy Benedict Member

    Center, MO
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    Jan 13, 2020
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    68
    Installed today and she fired right up !!! Very easy job. It performs well and would recommend it to others. Thanks guys.
     
  2. Jan 14, 2021
    hooliganrick

    hooliganrick Sponsor

    San Diego, CA
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    Apr 14, 2012
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    Late reply....but no ballast resistor...easy peasy...good work
     
  3. Jan 14, 2021
    Randy Benedict

    Randy Benedict Member

    Center, MO
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    Ran good with the ballast in place. Should I bypass it on the 1.5 coil?
     
  4. Jan 14, 2021
    SFaulken

    SFaulken Member 2021 Sponsor 2020 Sponsor

    Marysville, WA
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    Unless you need the ballast resistor to pull down the voltage for something else on the rig, there's no *good* reason, that I can think of to leave it in. Running a full 12 VDC to the pertronix unit, with the appropriate ignition coil isn't going to hurt anything, and it just eliminates one more potential failure point/device in the ignition circuit.
     
  5. Jan 14, 2021
    jeepstar

    jeepstar Well-Known Member 2021 Sponsor 2020 Sponsor

    Sheboygan
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    Doesn't the ballast resistor tell your alternator to charge? My battery kept dying until I put a ballast resistor in my jeep.
     
  6. Jan 14, 2021
    SFaulken

    SFaulken Member 2021 Sponsor 2020 Sponsor

    Marysville, WA
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    Not that I'm aware of, but it could. I've got a 10SI single wire in my CJ, so it's not tied into the ignition circuit at all. Might very well be true if you're still running the old externally regulated Motorola.
     
  7. Jan 14, 2021
    maurywhurt

    maurywhurt Member 2021 Sponsor 2020 Sponsor

    Western North...
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    When I was getting ready to install mine I called Pertronix to ask about this, and the rep there recommended going with a 3.0 ohm coil and bypassing the ballast resistor. He also said that if I wanted to retain the bypass resistor, I'd need to go with a 1.5 ohm coil.

    I believe the reason for this is that the total number of ohms that's correct for the 12v Pertronix module for normal (non-racing) driving applications is approximately 3.0. If you have a 1.5 ohm coil and a bypass resistor that's also around 1.5 ohms, that would equal a total of about 3.0 ohms of resistance - so a 3.0 ohm coil used without a bypass resistor will also work.
     
    Last edited: Jan 15, 2021
  8. Jan 14, 2021
    timgr

    timgr Eppur si muove. 2021 Sponsor 2020 Sponsor

    Medford Mass USA
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    That's a resistor, but not the ballast resistor.

    The ballast resistor limits current through the coil. The Pertronix unit sinks that current through a transistor to ground when the coil is "charging." Too much current and the transistor switch overheats and dies.

    Some ignition systems bypass the ballast resistor to "juice up" the ignition for starting. Without a separate ballast resistor from the coil, this action is not possible.

    Likely that 1.5 ohms resistance in the coil is determined entirely by the primary wire in the coil. Adding more resistance to the coil will make the coil run hotter. Better to put that extra resistance outside the coil case as a ballast resistor, than have it make heat inside the coil.
     
    Last edited: Jan 14, 2021
    jeepstar likes this.
  9. Jan 14, 2021
    SFaulken

    SFaulken Member 2021 Sponsor 2020 Sponsor

    Marysville, WA
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    Tim is basically right. I will say, the pertronix module in the 302 in my Dad's knockaround truck has been in there 20+ years, getting full 12VDC, and it's never missed a beat. And I believe that Pertronix itself warranties this use, if you look at the paperwork *assuming* you use the right coil. YMMV, and if it's something you're actually worried about, by all means, leave the ballast resistor there.
     

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