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1.5 or 3.0 Coil?

Discussion in '"Stock" Alpine' started by nsbluenose, Oct 5, 2020.

  1. nsbluenose

    nsbluenose Bronze Level Sponsor

    This question has probably been asked before, but I can't locate what has been said
    My car, with a 4 cylinder, 1725 cc engine, stock except for Pertronix ignition, is using a 3 ohm coil.
    Searching the internet, it seems to be nearly impossible to get a clear cut answer to, should it be a 1.5 or a 3.0 ohm coil? Does it make a difference? Advantage or disadvantage of one over the other.
    So, on stock, 4 cylinder engines with electronic ignitions, which should it be, 1.5 or 3.0 coils?
    Looking forward to the replies.
  2. MikeH

    MikeH Platinum Level Sponsor

  3. nsbluenose

    nsbluenose Bronze Level Sponsor

    Thanks MikeH. This article did help. I am using the Ignitor system, so for my engine 3.0 should be the correct coil.
  4. Tom H

    Tom H Platinum Level Sponsor

    If you have a 3 ohm coil be sure that you do not also have a Ballast Resistor wired in, as was on the SV Alpine from the factory. The ballast resistor is a rectangular ceramic piece about the size of a Chapstick originally mounted on the firewall brace near the coil.
  5. Alpine 1789

    Alpine 1789 SAOCA President Platinum Level Sponsor

    Moss Motors doesn't sell much for our cars, but they have a very good YouTube channel that covers a lot of relevant topics. They have a four part series on coils that I found very educational. Among other things, I finally understood the difference between ballasted and non-ballasted systems after watching it. You can find part 1 here:
  6. nsbluenose

    nsbluenose Bronze Level Sponsor

    No ballast resistor on the car. Is there such a thing as a 'in line resistor wire'? One of the guys in our local British car club mentioned this. Not 100% sure what he meant, other than it may have been used to replace the ballast resistor.
  7. MikeH

    MikeH Platinum Level Sponsor

    My 65 Mustang uses a resistor wire that runs from the ignition switch. I have a switch installed on it as an ignition cut out. Hidden as an anti theft device.

    The following is to help explain the resistor wire set up and does not represent the Alpine wiring.

    When cranking, the solenoid sends the full 12V from the battery on the brown wire to the plug where it ties to the Red/Green wire back to the coil. This gives a better spark when starting. When released, the Red/Green wire feeds Ignition power out of the Ign Switch through the resistor wire which drops the voltage to about 6-9 volts at the coil. This gives the points contacts longer life.
    Last edited: Oct 5, 2020

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