'72 ballast resistor, resitance wire or both?
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'72 ballast resistor, resitance wire or both?
I just put in a Mallory distributor, but am having a problem. My '72 has both a ballast resistor and what looks like a resistance wire. Everything I have found indicates it should have only one, the resistance wire. What does your '72 have?
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If someone added an aftermerket coil they may have added a ballast resistor too. 72 should have 2 wires to the + side of the coil- one from the starter and one from the ignition switch. The one from the switch is the resistance wire.
However- it was pretty common practice in the dealerships that if a car came in with a no start, and no power to the coil with the key "ON", to install a ballast resistor powered from the ACC side of the system.
However- it was pretty common practice in the dealerships that if a car came in with a no start, and no power to the coil with the key "ON", to install a ballast resistor powered from the ACC side of the system.
Last edited by TimAT; Aug 26, 2010 at 06:20 PM.
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Many non-hei ignitions were converted to electronic units that should NOT have the ballast resistor or resistor wire in the circuit. So, those folks swapped the resistance wire out for plain old copper wire. Then when the Pertronix [or whatever] failed...and they had no source for resistance wire..., a ballast resistor was substituted. You can use an ohmmeter to measure the resistance of the wire from the fuse panel (firewall side) to the + terminal on the coil. Just make sure that one end of that wire is NOT connected to anything else when you make that check. That wire should measure around 1.5 ohms for a car with a standard 'points' system. If you get less than .3 ohms for the measurement on that wire, it has been changed to regular wire.
You don't want to have BOTH the resistance wire and the ballast resistor in the circuit.
You don't want to have BOTH the resistance wire and the ballast resistor in the circuit.
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