getting ready to rewire my 68 coupe, my question is. according to the wiring diagram there is a "resistor" or a "resistor wire" off the coil to the ignition switch. my kit (ronfransis) came with the resistor but i don't want to use it if i don't need to (cleaner install). I have searched high and low for the resistor but cant find one any where so i assume the wire form the coil to ignition is a resistor wire. what is a resistior wire and where do i find one?

Thanks

 

the resistor wire is of pink color. in a stock mustang they usually go from ignition switch to the connector at the firewall. It looks like any other cable in there, just different colour.

You can check when measuring voltage coil+ against battery minus with ignition on. if you have ~12V (same as directly over battery) then you don't have that resitor wire anymore. If you measure around 8.5V then the wire is still in place

in my 64 model there is a very short cable going from ignition switch and after 2-3" there is a connector and the pink wire goes in that. I think the connector is only there for adding ford inline tachs (rally pac etc)

 

The only reason you'd need to remove/bypass the resistor wire is if you're adding an electronic ignition that needs (or can use) a 12V source. Keep in mind that you'll need to buy an aftermarket coil designed to run on 12V as well.

 

very true. seems like his set comes with a resistor, but if he still has his original one in place then he doesn't nee to add (must not add) a 2nd one
only way to be sure is measure voltage at coil

 

That actually doesn't always work. For that to work, you have to be running power through the coil, which only happens when the points (or transistor) are closed, telling the coil to charge. In a points system, obviously this is not always the case when the engine isn't running. An electronic ignition is much the same, although some electronic control modules are smart enough to shut off power to the coil in extended key-on-engine-off situations to keep from burning out the coil, module, or both.

The easier way to do it is to disconnect that power wire from the coil, hook it up to a light bulb, ground the bulb (turning it on), and check voltage at the wire. If it's 12+V, there's no resistor.

 

Good pull from Tad. Yep, resistors work by current drop and if it isn't hooked up to a ground, it won't drop the voltage (basic Ohms law) E=IxR (where e = volts, I = current, R = resistance) so Tads method of putting a load on the circuit by a light bulb forces the resistor ( if installed) to drop current which will drop the voltage.

 

The resistor wire cuts the voltage to the coil down so you don't burn the points up. It's a pink wire going from the ignition switch to the firewall connector. If you're running an electronic ignition (which you should) you don't need the resistor wire.

 

All thanks for the advice, Kalli, you site is great and helpful. i three things to consider then, car run and starts just fine, so leave the curict alone or add the resistor or go HEI. Knowing HEI is more efficient and expensive - your thoughts on the three options. Keep inmind i am looking to buils a street muscel car but would never street race