I'm converting my Firebird from a Mallory Electronic ignition system back to a stock distributor (maybe crazy but my Mallory is more for racing). I've heard of a "resistor wire" that attaches to the positive side of the coil. Does anyone have info about this wire? I checked out the wiring diagram and see one pink and one yellow wire but nothing indicates anything special about one of these wires. They currently appear to be attached to a ceramic block in the Mallory system. Is there a way to test if a wire is a resist wire (possibly measuring the resistance)? Any help and info is much appreciated. Thanks Dave
The resistor wire will only let about 9v through. Measure the voltage, and if it is a full 12v, the wire has been changed.
You can add a ballast resistor to a regular wire to do basically the same thing. The ballast lets full 12v thru until it warms up, and then reduces voltage to ~7-9v.
With points and a resistor wire, there is an additional wire from the second terminal on the starter to the coil. This allows a full 12v during startup. (mine is missing this and still starts fine)
Another question about the resistor wire---Does this wire go from the + side of the coil to the starter solenoid? I'm switching from a points to a ready to run MSD distributor and was wondering if the wire from the coil to the starter can be eliminated. There was only about 6.8 volts at the + coil terminal, so I guess this must be the resistance wire. The other wire going from the + coil terminal goes through the firewall under the dash. Is this the wire for the volt meter? If not, what is it? If anybody has any thoughts or tips about this swap, I'm all ears.
My 69 bird have the original underdash wiring harness intact and uncut, and as far as I know, the resistance wire should be in this harness. Might be different with earlier years though. The wire from the coil to the starter is probably used to provide the coil with a full 12 volts when cranking the starter.
My problem is, when measuring using a voltage meter at the coil, it's still a full 12 volts (and even 14+ volts with engine running). Using an aftermarket 1.8 ohm ballast resistor just for security measures, but it shouldn't really be needed...
on 67s the resistor wire runs from the plug on the firewall to the coil, but if your using the msd ready to run dist and an msd blaster coil or similar you may be able to replace the resistor with a regular wire to get a hotter spark
drvmarch- if you want to measure the voltage at the coil to see if you have a resistor wire the car must be running, you will get 12v either way if the car is not running but the key is in the on position
bruce1223- the wire might be for a tach if it is on the neg side of the coil, if its on the positive side, someone took power from that for something that was added. and if you take out the resistor then you can remove the wire to the starter
