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  1. #1
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    52

    Default LM318 Wiring Configuration Conumdrum

    I have a '72 Uniflite with later style Chrysler LM318's. I haven't been able to determine if the wiring on these engines is correct. The distributers have the after market Pertronix electronic ignition. Standard canister coil with single ballast resistor. All the wiring diagrams that I come across show an ECU installed in the system. My engines don't have the ECU and I'm wondering if I need one. I'm currently rewiring my engines and replacing components like the cap, rotor and ballast resistor. When I look online to find a replacement ballast resistor the single ones are labeled for points style distributer and the dual ones are for electronic ignition. I have electronic ignition but use the single resistor. I'm at a loss as what style and/or what wiring configuration that I'm supposed to use. Any help would be appreciated. Thanks

  2. #2
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    16,381

    Default Re: LM318 Wiring Configuration Conumdrum

    It's a classic case of 'over-engineering' by the normally competent folks who ran Chrysler back then. They weren't satisfied with having just one resistor circuit to the ECU, they had to have two of them, with different voltages! This absurdity went away eventually in that later ECUs have only 4 pins, eliminating that 2nd resistor circuit all together.

    The bottom line is that all you need is one ballast resistor circuit to keep the voltage down during RUN (and be out of the circuit during START).

    Jeff

  3. #3
    Join Date
    Dec 2014
    Location
    Ontario Canada
    Posts
    84

    Default Re: LM318 Wiring Configuration Conumdrum

    I have a 1972 Uniflite as well and pertronic upgrades to the distributors. Mine runs on a single ballast resistor, standard coil and works the way fastjeff describes. The part numbers are Ballast resistor Sierra 18-5450, distributor cap Mopar 2098852, pertronix ignitor 1581 This is the older style Pertronix upgrade. I'm sure there are newer ones.

  4. #4
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    52

    Default Re: LM318 Wiring Configuration Conumdrum

    Thanks Jeff and Tooni,

    I was online looking at the PerTronix ignitor installation instructions and they recommend removal of the ballast resistor or resistor wire circuit completely. I did a little research and it sounds like the only reason the resistor is there is because with the old style points you don't want them to arc or weld shut under higher voltage. But with electronic ignition you don't need the lower voltage. Is this right? I would love to remove that extra resistor and run a continuous wire straight to the coil. Less room for problematic wiring issues around the salt air. Do you guys know of anyone that runs the electronic ignition without the ballast resistor? ( Pertronix or similar ) Thanks

  5. #5
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    16,381

    Default Re: LM318 Wiring Configuration Conumdrum

    IF you are using the Chrysler type ECU (ignition box), you MUST run in through a ballast resistor or it will fail (as both of mine did last year).

    The way the circuit is supposed to be wired, 12 volts goes first to the4 ballast resistor, then to the ECU and coil. The motors ran perfectly after I 'did it right'.

    Jeff

  6. #6
    Join Date
    Dec 2014
    Location
    Ontario Canada
    Posts
    84

    Default Re: LM318 Wiring Configuration Conumdrum

    If you run the old Ignitor model by Pertronix you will need a ballast resistor. If you use their newer Ignitor II or Ignitor III models you can get rid of the ballast resistor. Just make sure it is marine grade.

  7. #7
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    52

    Default Re: LM318 Wiring Configuration Conumdrum

    Thanks Tooni,
    It hurt the pocket book but I purchased new Pertronix distributers with ignitor 2 ignition. Also new Pertronix coils compatible with the ignitors. Hence no ballast resistor circuit.

  8. #8

    Default Re: LM318 Wiring Configuration Conumdrum

    Hi how are ya? Sorry to jump in middle of your forum, I also purchased a new Pertronix distributor and .6 ohm Pertronix coil for our 1969 Chrysler 318, can you please tell me, when you eliminated the resistor, do those wires now get hooked up to the new coil, and which ones where?? Lol.. I’m not very good at the electrical part of it and don’t wanna screw something up.. thanks sooo much for any help.. I’m trying to finish it as we speak..

  9. #9
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    52

    Default Re: LM318 Wiring Configuration Conumdrum

    Hey Rub, Yes remove the resistor and run the wire directly to the positive stud on the coil. This should be the same wire that goes to the ignition switch. The negative side of the coil is for your tach. I didn’t like having a splice in mine so I replaced it with one solid chunk of wire from the ignition switch to the coil. It works great!! Pertronix also has good PDF docs on installations for your coil. Here’s an example http://www.carid.com/images/pertroni...structions.pdf Good luck!!

    Russell

  10. #10
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    11,454

    Default Re: LM318 Wiring Configuration Conumdrum

    Rub, you have resurrected a thread from April 2015. It's always best to start a new/fresh thread for your specific issue.

    That said...... hopefully your new Pertronix system is Marine. The auto version advance curve will be incorrect for Marine use, not to mention that it would not be ignition source protected.


    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  11. #11

    Default Re: LM318 Wiring Configuration Conumdrum

    Hey thanks so much.. I appreciate it. Im still trying to figure out how to post to the site and how to start a new thread.. Yep it’s all marine... I do good with most things, just really stink at wiring.. Thanks again.. I will work on trying to learn how to post on here. Thanks again and God bless

  12. #12

    Default Re: LM318 Wiring Configuration Conumdrum

    Maybe Ric can quote the rules established for exactly what disqualifies a "dated thread". Seems that Rub has received the info he needed without starting from scratch, as well as a refresher for others.

  13. #13
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    11,454

    Default Re: LM318 Wiring Configuration Conumdrum

    mcomm, there are no rules against posting to an old thread.
    Perhaps in time, you will have gained enough forum experience to see the value in starting a new thread -vs- posting to an old one.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  14. #14

    Default Re: LM318 Wiring Configuration Conumdrum

    Again more uselessness.

  15. #15

    Default Re: LM318 Wiring Configuration Conumdrum

    Wow every forum has them an mcomm I guess..

  16. #16
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    11,454

    Default Re: LM318 Wiring Configuration Conumdrum

    Quote Originally Posted by Rub View Post
    Wow every forum has them an mcomm I guess..
    Yes, and we have two of them...... Spike and Chester!
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

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