Correct Ballast resistor

Electrical and Ignition

  1. Princess Valiant

    Princess Valiant Duster specialist FABO Gold Member

    Messages:
    23,693
    Likes Received:
    16613
    Joined:
    Dec 14, 2011
    Location:
    Colorado
    Local Time:
    8:17 PM
    So I am shopping around for an electronic ignition upgrade kit for my 71 scamp and I am noticing that some kits on the market have the bracket style ballast resistor and some have the thick style one that takes a longer bolt.

    Which is more correct and which one should I get ??

    dcc-2444641_ml.jpg

    188069_BallastResistor2prong_1.jpg
     
  2. Mattax

    Mattax Just the facts, ma'am FABO Gold Member

    Messages:
    11,267
    Likes Received:
    7128
    Joined:
    Feb 7, 2013
    Location:
    Phila. Pa
    Local Time:
    10:17 PM
    The top one visually looks correct for a factory points system circa 1967.
    But since you are changing ignition systems, the functional requirement is for the resistance to match the coil and ECU. You'll have to get that from the coil and ECU manufacturer. Been some recent discussion about this, shouldn't be too hard to find the info for which ever ones you're looking at. If its an older MP system, there's a page in the Ignition Bulletin for the different Direct Connection boxes etc.

    Ballast resistors for Points: Chrysler master tech bulletins
    Ignition System Analysis 1969, see pages 4-5
    Ballast resistors for the era electronic ignitions
    from 1972 MTSC Ignition Service (Session 292)

    Later Chrysler ECUs use single ballasts.
    Early Chrysler ECUs used dual resistor with one dedicated to controlling ECU current as explained on this page
    1973 Chrysler Electronic Ignition Diagnosis and Repair (Session 312)
     
    Last edited: Mar 26, 2018
    • Like Like x 1
    • Princess Valiant

      Princess Valiant Duster specialist FABO Gold Member

      Messages:
      23,693
      Likes Received:
      16613
      Joined:
      Dec 14, 2011
      Location:
      Colorado
      Local Time:
      8:17 PM
    • fklskv

      fklskv Well-Known Member

      Messages:
      1,197
      Likes Received:
      645
      Joined:
      Aug 14, 2011
      Location:
      Lackawanna, NY
      Local Time:
      10:17 PM
      Unless your going for period correct I would recommend the electronic dizzy with a HEI setup and ditch the ballast resistor altogether. There is a big performance difference.
       
      • Agree Agree x 2
      • Princess Valiant

        Princess Valiant Duster specialist FABO Gold Member

        Messages:
        23,693
        Likes Received:
        16613
        Joined:
        Dec 14, 2011
        Location:
        Colorado
        Local Time:
        8:17 PM
        hadn't thought of that. Its not a correct car by any means but it is a very mild street car. The engine is a tired, original, low compression 340.
         
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

        Messages:
        11,267
        Likes Received:
        7128
        Joined:
        Feb 7, 2013
        Location:
        Phila. Pa
        Local Time:
        10:17 PM
        Looks that way. They might both have the same resistance reading.
        Visually the distributors look the same but have different ECUs.
        For a 340, I'd say the odds are better that Rick's is going to be a better match. Internally, the curve in his distributor has been set up like the old MP or 440 HiPo.
        Getting the right timing curve is more important than any other characteristic. Properly curved dual point will beat an improperly curved anything else. No amount of spark energy is going to change that. A lot of sharp racers found that out in the 70s.

        edit: added link to 440 timing curve
         
        Last edited: Mar 26, 2018
      • d1970

        d1970 TODAY IS A GOOD DAY TO HAVE A GOOD DAY

        Messages:
        373
        Likes Received:
        169
        Joined:
        Sep 29, 2015
        Location:
        Ontario, Canada
        Local Time:
        9:17 PM

        it doesn't matter what style the ballast is, all that matters is the Ohm size. I was told years ago by a Mopar mechanic for Mopar electronic ignition systems using a stock coil you should use a ballast that has 1.2 - 1.4 ohms resistance. I've allows use one in that range and have never had a problem in 30+ years with my Mopars electronic ignition systems. Here is a list of different ballast resistors I've collected over the years incase I needed one.
        NAPA Echlin ICR11 (1.35 Ohms), NAPA Echlin ICR23 (1.2 Ohms), NAPA Echlin ICR34 (1.4 Ohms), Standard RU-4 (1.35 Ohms), Standard RU-23 (1.2 Ohms), Standard RU-37 (1.4 Ohms).

        I always keep a spare in the glovebox so I will never be stranded on the side of the road. Even thought I only had 2 go south in all my time I've owned my Mopars. They are an electronic piece of equipment and you never know when it will stop working and I've help a few other Mopar owners over the years (that needed a ballast) with problems with their car not starting. Just my two cents worth.
         
        Last edited: Mar 26, 2018
        • Like Like x 2
        • cuda66273

          cuda66273 Well-Known Member

          Messages:
          251
          Likes Received:
          21
          Joined:
          May 22, 2004
          Location:
          Oregon
          Local Time:
          3:17 AM
          Which is more correct and which one should I get ??

          View attachment 1715157640

          View attachment 1715157641 [/QUOTE]

          How about NONE of the above, upgrade to an Ignition System that doesn't run on 5-6V through a ballast resistor and ignition from the 1960's, join us here in this century.

          The HRR688 will upgrade it and you'll never have carry a spare ignition part again.

          The Only Ignition components with a 5 YEAR WARRANTY, Distributors and ECU's
           
        1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
          By continuing to use this site, you are consenting to our use of cookies.