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Ballast Resistor Wiring


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Just installed Pertronix in my 70 2002 with red coil.  I have read the other posts related to the topic but none identify the ignition side of the ballast resistor.  I assume it is closest to the firewall and marked with a dot.  Could someone kindly confirm?  I just have both Pertronix leads run directly to the coil right now which works fine but would prefer to connect to the ignition side of the ballast resistor as called out in the instructions.

 

Thanks!

 

Brad

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Resistors work in either direction, doesn't matter which way it is oriented, there may be a bypass wire for starting or it may have been removed.  If you are trying to figure out how it is currently configured you can unplug one side and turn the ignition switch on then test for power on either side of the resistor, if there is power then you just disconnected the coil side, if not then you just disconnected the input side.  If you are wiring up your Pertronix you want to plug the red wire to the input side of the resistor so it receives the full 12+ volts.

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  • 8 years later...

I have removed the resistor wire and replaced it with a proper ballast resistor, new wires and a new coil. I also installed a wire from the starter directly to the coil for starting. I did remove all the smog stuff and wiring. The car starts (power from the starter) but power drops when I go to run and the engine dies. In addition the ballast resistor gets mad hot. Start a fire hot. Any ideas?

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8 minutes ago, Dr G-man said:

The coil called for .9 ballast resistor. So I installed one. Otherwise I shorten the life of the coil right? 


The approximately 3 ohms total resistance needed in a points system is to protect the points not the coil. 
 

If the engine dies in “run” you have wired it incorrectly. 

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2 hours ago, Dr G-man said:

I have removed the resistor wire and replaced it with a proper ballast resistor, new wires and a new coil. I also installed a wire from the starter directly to the coil for starting. I did remove all the smog stuff and wiring. The car starts (power from the starter) but power drops when I go to run and the engine dies. In addition the ballast resistor gets mad hot. Start a fire hot. Any ideas?

where on the starter did you wire from?

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Check that the wire from the starter to the coil is correct. Should be the #15 tab on the starter solenoid to #15 tab(+) on the coil.

This provides a non-resistor voltage source to the coil only during cranking. When the ignition switch returns to the RUN position, this voltage is turned off (which may explain why your engine dies). The voltage to the coil is then provided by the unfused side of fuse #12.  This is where the resistor comes in...between the fuse box and the +coil. As Lorin said, a .9 Ohm resistor is typical for a non-resistor coil. If you have a big resistor AND a resistor coil, you could get no spark and big heat.

Also, if the .9 Ohm resistor wire (used on "74-'76 cars) is removed, an external resistor is usually bypassed by a relay during cranking, and therefore the wire (Black/red) from the starter is not needed.

Here's a sketch...hope it helps.

 

Ignition Circuit.jpg

 

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I will check the wiring tomorrow. I am confident that the starter wire is correct.

 

The comment about both a ballast resistor and an internally resisted coil might provide a clue. 
 

I am going to bypass the ballast resistor and see what happens. 
 

thank you 

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It's easy to connect the Black/red on the starter to the wrong tab. If it goes to #50 with the Black/white from the START position on the ign. switch, the car would start during cranking and die on RUN. The #15 tab is usually smaller than the others on the solenoid.

 

Starter connections.jpg

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