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Thread: Unilite, coil & ballast resistor compatibility confirmation.

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  1. #1
    Join Date
    May 2018
    Location
    UK
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    Default Unilite, coil & ballast resistor compatibility confirmation.

    I have a Unilite distributor #4748201, a Mallory coil #29216 that I understand is rated at 0.7 Ohms, and a 0.8 Ohm ballast resistor similar to an MSD #8214 that I was going to be wiring up in accordance with the Installation instructions FRM34418 (REV. B) 09/17 figure 1. Through searching I am led to believe that this was a recommended combination prior to the ProMaster coil and resistor combo but can an MSD Tech please confirm their compatibility?

    With reference to wiring, I also found this Q & A on the Holley Ignition Technical Support page:
    Question
    What coil should I use for my Mallory Unilite distributor, and/or Mallory Hyfire CD ignition box?
    Answer
    All Unilite distributors need coils with a minimum amount of 1.4 Ohms primary resistance. Coils are 12 volts; however, they do have different amounts of primary resistance, which is measured in Ohms. You can still use a coil with less than 1.4 Ohms, but you must install a Ballast Resistor (Mallory #700) between the coil and the distributor, install on Red wire coming out of the Unilite distributor. It is Important to know that the Unilite distributor will work initially on the engine with less than 1.4 Ohm, BUT NOT FOR LONG. It only takes a short period of time to burn up the module using a coil with the wrong resistance.
    When you select a coil for any High power CD ignition box like the Mallory Hyfire CD boxes, the Mallory Hyfire CD boxes MUST always use a coil with LESS than 1 Ohm of primary resistance.


    It proposes that a ballast resistor is fitted in the RED power supply wire between the coil negative (-) terminal and the distributor. But according to the latest Installation Instructions FRM34418 (REV. B) 09/17, the RED power supply wire connects directly to an ignition switched 12V source and it is the GREEN trigger feed that has the ballast resistor fitted before the coil to lower the voltage/amperage entering/exiting the coil and feeding the trigger side of the module. Please, what is correct? Thanks.
    Last edited by nomad56; 03-07-2019 at 12:40 PM. Reason: Added a 2nd ques
    One of the UK's three 56 Nomads. 350/350/9"/4" closer to the weeds

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