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Ballast Needed with Pertronix Ignitor?

Discussion in '"Stock" Alpine' started by fastfrontier17, Apr 11, 2022.

  1. fastfrontier17

    fastfrontier17 Donation Time

    I have a pertronix ignitor on my SII 1600. The coil appears stock, and is measuring 1.5-1.6 ohms at around 70°F. The car came with an aftermarket 2 ohm ballast resistor. I have read on this forum that a ballast resistor is more intended for cars with points, and may not be required with an electronic ignitor. Can someone confirm this? Currently, the ignitor, coil, and ballast are wired as shown in the red box of the photo attached.

    Attached Files:

  2. husky drvr

    husky drvr Platinum Level Sponsor


    This link is for a "Hot Rod" article, dated May 2001. It answers your question, in a bit of a sideways manner.


    Hope this helps,
    fastfrontier17 likes this.
  3. Thor 1211

    Thor 1211 Silver Level Sponsor

    I thought my Petronix came with instructions to ditch the resistor. I did and the car ran and started better than ever. Or maybe it was the coil, I also installed the hotter coil.
    Scotty and RootesRooter like this.
  4. fastfrontier17

    fastfrontier17 Donation Time

    Mine came with the ignitor already installed, so dunno about any original instructions.
  5. fastfrontier17

    fastfrontier17 Donation Time

    Thanks. Based on the statement below, then my current 1.5 ohm coil should suffice. Now I just need to go physically look at my current wiring to see how to match figure 2 of the pertronix diagram.

    "The Ignitor should be used with coils of 1.5-ohm resistance or greater, while the Ignitor II can benefit from higher-powered, super-low-resistance coils."
  6. absunbeam

    absunbeam Gold Level Sponsor

    If you want to keep a ceramic resistor under the hood for that “stock” look, you can solder a wire to jump between the coil. Nick Kinter had done that to his resistor. He along with 3 other Petronix users (myself included)had coil failure on the trip to the tail of the Dragon with resistors in place.
  7. fastfrontier17

    fastfrontier17 Donation Time

    When anyone happen to know if a new ballast is to smell funky when first using? Like burning off something residual?
  8. Scotty

    Scotty Donation Time

    I have something similar made for the Lucas Distributor and I’m only using an updated coil, no Ballast Resistor. So far, one of the best investments I’ve made. HUGE difference.
  9. Scotty

    Scotty Donation Time

    That usually means it’s gone bad. Be careful because that could cause a fire.
  10. jumpinjan

    jumpinjan Bronze Level Sponsor

    If a resistor goes bad, it becomes "opened"...the circuit dead...not alive.
  11. fastfrontier17

    fastfrontier17 Donation Time

    Measured 2 ohms new, and measured 2 ohms just now. I know ballast resistors get hot, and it's not smoking, but sure smells funny with ignition on for 10 seconds or so
  12. fastfrontier17

    fastfrontier17 Donation Time

    Man, wired up the battery again today and turned the key to ON and still that funky smell from the $6 ceramic resistor. Wish I knew enough about the spring and string inside the resistor to know if something was just burning off. I assume its a Ni-Chrome spring, no clue about the "string" unless its dipped in some type of wax or some sort of sizing.
  13. Barry

    Barry Platinum Level Sponsor

    You are not supposed to leave the ignition key in the "on" position for any length of time unless the engine is running.

    The ballast resistor (2 Ohms), ignition coil (1.5-1.6 Ohms) and the Pertronix Ignitor (close to zero resistance when "on") form a series circuit. With the ignition key in the "on" position and the engine running, the Pertronix Ignitor (an electronic on/off switch that replaces mechanical "points") is only conducting current about half the time and the average current through the series circuit consisting of the ballast resistor, the coil and the Pertronix Ignitor is probably a little less than 2 Amps. That means the ballast resistor produces about 15 Watts of heat energy per second. With the engine running, the ballast resistor will typically get pretty warm, but not hot.

    With the ignition key in the "on" position and the engine NOT running, the current (both average and continuous) through the series circuit is close to 4 Amps which means that the ballast resistor produces (and has to dissipate) almost 30 Watts of heat energy per second and the ballast resistor gets very hot very quickly.

    Mounting the ballast resistor where there is appreciable airflow helps to control the temperature problem.
    Last edited: Apr 12, 2022
  14. fastfrontier17

    fastfrontier17 Donation Time

    Thanks for the reply. I left it in ON temporarily to test out a new OD solenoid. Now that I'm thinking of it, I'm not sure if it has to be on the on position to test the solenoid, but I did it that way regardless.

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