What Gauge Wire for a Duraspark Conversion?

[colnago]

All,

I've decided to convert to a Duraspark ignition setup for the rebuild. I figure that the wiring harness is a relatively easy thing for me to do, and it gives me the freedom to mount the box anywhere and not worry about being limited to wire lengths. I've done some googling, and have found that people are using anywhere from 12 gauge to 16 gauge wire for their wiring harness. Obviously, I'd like to use as light a gauge as possible, simply doe to the ease of routing it around. Does anyone know what gauge (or gauges) I should be using?

Also, I'll probably use a relay to provide 12V where appropriate. What capacity relay should I be using?

Thanks,

Joseph

[sargentrs]

A 25-30A relay is sufficient. Here's the relay I used https://www.summitracing.com/parts/bch- ... Ar_h8P8HAQ The basic harness from the 4 prong plug to the distributor is 16ga. I used 10ga for the source wire from the battery to the relay. I used 12ga for the relay ground wire. I used 14ga for the red and white wires from the 2 prong plug to the relay and solenoid and 14ga to the coil. Here's how I wired mine. I leave the original wires (brown and red/blue) connected to the solenoid. Doesn't hurt anything and keeps the original circuitry intact. I also don't touch the original ignition switch wiring. If you ever want to go back to points just pull the Duraspark stuff, drop in your old points distributor and plug it back into the original harness.

[colnago]

Randy,

Any suggestions on how to route the wiring? My thoughts:

- Mount the ECM on the passenger fender
- Mount the relay on the firewall
- Bring the ballast resistor to the relay
- Run all wiring down the fender, across the firewall, and up the engine, on the driver side of the carb

Any problems with bundling all of the wiring together (cross-talk or ignition noise)?

Joseph

[Ranchero50]

You ever look at the factory wiring after the insulation flaked off? 18 gauge, maybe 16. I wouldn't even bother with a relay.

They are susceptible to heat so make sure it stays in a cool location. If I remember, Mustang II's had trouble because owners would change something like the air filter housing to an open element type and it would cause a localized hot spot at the module and they would fry. Generic modules were $10 at Kmart, right next to the light bulbs.

On my '83 Twin turbo project I mounted it inside the cabin on a length of aluminum plate that also held the starter solenoid and a terminal strip. I'd do something similar to the truck, possibly on the passenger side door jam behind the dash where the bigger trucks have the light relays.

[sargentrs]

Randy,

Any suggestions on how to route the wiring? My thoughts:

- Mount the ECM on the passenger fender
- Mount the relay on the firewall
- Bring the ballast resistor to the relay
- Run all wiring down the fender, across the firewall, and up the engine, on the driver side of the carb

Any problems with bundling all of the wiring together (cross-talk or ignition noise)?

Joseph

That would work just as well. I mounted mine on the driver's side inner fender, spaced up on some small pieces of rubber hose, more to the forward end of the fender than the center or rear. This kept the box further away from exhaust manifold and closer to the grill and radiator fan. I ran the ECM/distributor part of the harness back to the firewall and up the valley between the valve cover and the intake. I mounted the relay on the passenger side inner fender near the solenoid. I ran the red and white power wires across the firewall, along the original harness to the solenoid, to the relay and then from the relay back to the firewall and across the passenger side valve cover to the coil. All of this gave me the large bulk of the wiring the shortest distance so all I had going across the firewall was the 2 red and white wires. I have experienced no electrical interference at all across any of the wiring. Running the full 12v from the relay and a stock Duraspark coil eliminated the need for the ballast resistor.