"65" Resistor Wire Voltage

Discussion in 'Classic Mustang Specific Tech' started by blu2u, Jan 23, 2009.

  1. The 302 engine is not yet running.I am told that I should have 8 or 9 volts at the resistor wire. I turned the key on and checked the resistor wire at the coil. I have 5.5 volts. Do I have a problem? Thanks
  2. It should be 6-9 volts. What is the voltage at the battery with the key on?
  3. Thanks Tim,
    I'll check the battery voltage tomorrow and get back to you. I wonder if it is because I used the new distributuor and coil from Summit?
  4. I measured the voltage and with the key on have 12 volts at the battery and 5.5 at the coil. What do you think?
  5. Hi Tim,
    Thanks for the diagram. I ran the new wire and spliced as per the drawing. I capped the pink wire off. Now I have 10.75 volts at the coil. My coil gets hot to the touch. Should I put a resisitor in line? Thanks
  6. Yes, 10.75 is too much. As stated in the installation instructions it should be between 6 and 9 volts. I ran a ballast resistor on mine a while back when I re-wired it and I was still running points.

    Apparently your resistor wire is too high and it is dropping too much voltage. (The higher the resistance, the more voltage dropped)

    If you can measure or find out what the resistance of your coil is, you want a ballast resistor to be a tad less than that amount. For instance if your coil is 1 ohm, you would want a .8 ohm ballast resistor.

    You can pick one up at a local auto parts for around $10

    Here is an MSD ballast resistor.
  7. I don't see in the thread which coil and distributor you got from Summit. I put in a MSD Blaster and replaced the points with a Pertronix unit. It's a stock style coil, but I needed to run a full twelve volts (switched) to the distributor.