The ignition system is a glutton for punishment. As the miles rack up, the distributor wears out, the coil gets abused, and the spark plug wires melt. The steadfast ignition system only gets attention when it starts falling down on the job.
This 1991 Mustang GT’s ignition system is a perfect case study. Its original distributor had over 100,000 miles, the coil’s terminal was pitted from a loose coil wire, and the plug wires’ boots were burned by the car’s equal-length shorty headers. Rather than simply replace the worn parts with the same ones that failed in the first place, we acquired some solid upgrades from Performance Distributors in Memphis, Tennessee.
When selecting ignition components, the options can be dizzying. Fortunately, Performance Distributors draws from its decades of automotive electrical experience to engineer the best components available.
To refresh the ignition system on this 1991 Mustang GT, Performance Distributors sent over a set of their LiveWires spark plug wires, Screamin’ Demon coil, Hot Forged DUI distributor, and nifty billet aluminum wire looms.
The centerpiece of this upgrade is the Hot Forged DUI distributor, which features a body machined from a “hot forging” that Performance Distributors claims is denser and cleaner than die cast or billet aluminum. The distributor includes their Dyna-Module programmed for longer spark duration that increases throttle response and low-end power. The distributor includes a brass terminal cap and rotor, and a steel gear compatible with our factory roller camshaft.
Performance Distributors’ Screamin’ Demon coil is rated at 45,000 volts and allows larger spark gaps for improved performance. The coil fits the factory mount and features a brass terminal for better conductivity over a longer life.
Transferring the spark energy from the distributor to the spark plugs are Performance Distributors’ LiveWires. The spark plug wires often have the hardest job, but the LiveWires are designed to protect themselves in the harsh underhood environment. The spiral-core, low-resistance 8mm conductor is protected with a high-temperature, non-flammable glass braid. Performance Distributors mentions it’s similar to the material used to seal contemporary cooking ovens. Not only does it help protect the wires from up to 1,400° F, but we found it helps structurally support the wire, making it less prone to “droop” down on the headers. The wires are numbered to correspond to each cylinder, which takes the guesswork out of routing the wires.
To finish off our LiveWires installation, we used their billet aluminum wire looms that fit perfectly over the sleeving and kept our wires spaced evenly and away from hot engine components.
Check out the accompanying photos and captions for the details of our installation.
To refresh the ignition system on a 1991 Mustang GT, Performance Distributors sent over a set of their LiveWires spark plug wires, Screamin’ Demon coil, Hot Forged DUI distributor, and nifty billet aluminum wire looms.
Performance Distributors’ Hot Forged DUI distributor features a body machined from a “hot forging,” which Performance Distributors claims is denser and cleaner than die cast or billet aluminum. The distributor includes their Dyna-Module programmed for longer spark duration that increases throttle response and low-end power.
Performance Distributors’ Hot Forged DUI for 5.0 engines includes a steel gear compatible with the factory roller camshaft.
The Performance Distributors’ Hot Forged DUI features all new components including an internal hall-effect pickup, cap, and rotor.
Performance Distributors’ Screamin’ Demon coil is rated at 45,000 volts and allows larger spark gaps for improved performance.
The LiveWires feature a spiral-core, low-resistance 8mm conductor that’s protected with a high-temperature, non-flammable glass braid. Not only does it help protect the wires from up to 1,400° F, but we found it helps structurally support the wire, making it less prone to “droop” down on the headers. The wires are numbered to correspond to each cylinder, which takes the guesswork out of installation.
These nifty billet aluminum wire looms keep the wires separated and supported...and off our headers.
The ignition system on this 100,000-mile 1991 GT needed attention. The wires were mismatched and burned from a sloppy installation.
When we removed the coil wire, we found the coil terminal was pitted from the wire terminal being loose.
This car’s equal-length shorty headers and sloppy wire installation did a number on the spark plug boots.
First, we unplugged the ignition module plug from the factory distributor.
After removing the distributor cap, we marked the orientation of the rotor. We’ll reference this position later.
Then, we removed the distributor hold-down from the block.
With everything disconnected, we removed the distributor.
Before installing the Performance Distributors Hot Forged DUI, we lubricated the distributor gear with the supplied assembly lube.
Next, we slid the distributor into the block and turned the rotor clockwise until the distributor dropped into position.
We pulled up on the distributor and twisted the rotor forward or backward until the rotor was in the same position we marked on the old distributor.
Next, we loosely installed the distributor hold-down bolt.
Then, we reconnected the ignition module.
The original coil on this Mustang was ready for retirement. We disconnected the wiring harness and removed the coil from the mounting bracket.
The Performance Distributors Screamin’ Demon coil fits in the factory location, but packs a higher-voltage punch.
We before installing the spark plug wires, we squirted some of the supplied dielectric grease inside the boots.
The numbers on the Performance Distributors LiveWires took the guesswork out of installing the wires. We just installed them counter-clockwise on the cap in the firing order: 1-3-7-2-6-5-4-8.
After connecting the coil wire to the Screamin’ Demon coil, we reinstalled the factory coil cover and routed the coil wire through the cover’s slot.
We used the supplied billet aluminum wire looms to secure the wires and keep them away from the headers and other engine components.
Much better! Not only does this engine compartment look neat and tidy, the ignition system packing a bigger punch.
Since we removed the distributor, we needed to reset the ignition timing. First, we disconnected the “SPOUT” connector on the ignition module harness.
Finally, we set the ignition timing to our desired specs using a timing light and tightened down the distributor hold-down bolt.
Photography by Wes Duenkel