Ignition Resistor Wire

[jmassey6]

Hello all:

In reviewing the National Parts Depot website, I found a resistor wire entry/listing and was wondering if my 1973 Ford Mustang Mach I with 351C and C6 needed this part.  Below is the part in question.  Unfortunately, I cannot locate either connection points for the part in my wiring harness or engine bay and therefore, I wasn't sure if I needed it.  Any help would be greatly appreciated.  Thanks!

-Jeff M.

:thankyouyellow:

 

[TommyK]

Hopefully Midlife will chime in but I believe that is for 65-66 only. Our cars have a resistance wire but it does not have plugs on either end like that. The resistance wire was used by Ford to reduce the voltage to the coil/points. In most cases when using modern ignition components you would be bypassing the factory resistance wire to get full battery voltage.

 

[midlife]

Midlife here...yes, all 64.5 - 73 Mustangs used a resistor wire. NPD's offer has plugs on both ends, and usually, only the 4.5-68 models had plugs on one end; all others did not use plugs. The resistor wire cannot be soldered, so splices must be used with crimp-type connectors.

On 71-73 Mustangs, there are two versions for where this wire goes. For tach dashes, the wire runs from the tach plug to the back of the fuse box junction box. For standard dashes, the wire runs from the ignition switch to the same location of the back of the fuse box.

 

[delawarebill]

i'm not totally up on the wiring of our cars.. try to stay away unless needed.. but i'll assume u have a factory tach.. then u need the resistor wire. for the tach uses that wire to work.

 

[midlife]

Actually, all Ford products that use points and condenser require the resistance wire to cut voltage to the coil so that the points don't wear out incredibly fast. Whether you have a tach or not, the resistor wire is still needed.

Some aftermarket ignition systems like a reduced voltage at the coil; others require a full 12V. If the latter, you can remove/replace the resistor wire.

 

[jmassey6]

Actually, all Ford products that use points and condenser require the resistance wire to cut voltage to the coil so that the points don't wear out incredibly fast.  Whether you have a tach or not, the resistor wire is still needed.  

Some aftermarket ignition systems like a reduced voltage at the coil; others require a full 12V.  If the latter, you can remove/replace the resistor wire.

Thanks Midlife!  Love the blue shirt by the way!  I do have a factory tach on the car and I installed a Pertronix Ignitor II electronic system using the original type FoMoCo Distributor (NOS) and removing the points and condensor with their additional power relay kit as noted below in CJ Pony Part's description and photo below.  Does that mean I still need the resistor wire and if so, should I purchase the NPD one and cut the ends off?





Product Description

Pertronix Ignition Power Relay Kit for all 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984 and 1985 Mustangs.

Pertronix's Ignitor II and III ignition systems require a full +12V power connection between the ignition switch and the positive coil terminal. This requires bypassing the ballast resistor or resistance wire. In many cases, the original resistance wire is buried in the vehicle's wiring harness. Adding a Pertronix power relay will eliminate digging through the wiring harness and replacing wires. This 30 AMP relay kit can also be used with the original Ignitor conversion kits as well.

 


Benefits:


-Minimizes conducted voltage spikes by isolating the ignition power source from other high current equipment


-Provides consistent full battery voltage. No more voltage fluctuations from over loaded ignition switches


-Eliminates problems from worn-out and corroded ignition switches, connectors and wires


-Universal design that works with most battery ignition systems


-Small size to keep your engine bay looking stock

If you have an older Mustang, you've probably replaced the points and condenser in the distributor a few times during tune-ups. However, what if there were modern parts for classic Mustangs that eliminate the need for much distributor maintenance? With the products from Pertronix, there is, allowing you have a much more reliable and maintenance free ignition. These products, along with the other high quality upgrade parts from Pertronix can help give your ignition system a complete make-over!

 

[midlife]

As the description says, you need a full 12V between the ignition switch and the coil, but the resistor wire sits between the ignition switch and the coil! The resistor wire runs from the output of the tach to the back of the fuse box; you'll need to pull that pin out of the back of the fuse box and run a separate wire from the female side of the output of the tach to that pin location. I do not know if that will change your tach reading, but if it does, a few 100 RPM at most.

 

[jmassey6]

As the description says, you need a full 12V between the ignition switch and the coil, but the resistor wire sits between the ignition switch and the coil!  The resistor wire runs from the output of the tach to the back of the fuse box; you'll need to pull that pin out of the back of the fuse box and run a separate wire from the female side of the output of the tach to that pin location.  I do not know if that will change your tach reading, but if it does, a few 100 RPM at most.

Thanks Midlife...I surmise that the full 12V as noted above is a separate wire to replace the resistor wire, correct?  Do I just abandon the resistor wire if it is present?  

-Jeff

 

[midlife]

Yup. Both.

 

[jowens1126]

anyone have pictures of the Resistor wire?

 

[Keith Williams]

Midlife here...yes, all 64.5 - 73 Mustangs used a resistor wire. NPD's offer has plugs on both ends, and usually, only the 4.5-68 models had plugs on one end; all others did not use plugs. The resistor wire cannot be soldered, so splices must be used with crimp-type connectors.

On 71-73 Mustangs, there are two versions for where this wire goes. For tach dashes, the wire runs from the tach plug to the back of the fuse box junction box. For standard dashes, the wire runs from the ignition switch to the same location of the back of the fuse box.

is the resistor built in to the factory wireing harness on tach harnesses and already in place thank you randy