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When I first bought my '69 it had a points style distributor with a Mallory E-Spark conversion kit installed. Instead of connecting the starter wire and resistor wire to the ignition coil, it had the starter wire and an ignition wire running off of a ballast resistor. I assume this is because the engine wiring harness resistor wire failed in some way while the car was under previous ownership.
Shortly after I bought the car I discovered several issues with the engine wiring harness and decided to replace the whole harness with a new one. During the install I referenced the 1969 assembly manual and dutifully connected the starter and resistor ignition wires to the ignition coil. I left the ballast resistor disconnected.
Mallory instructions claim that for an E-Spark unit paired with their ignition coil a ballast resistor is recommended but not necessary.
After giving it a little thought, I'm curious about the pros/cons of using the resistor wire over using the ballast resistor.
There are obviously several ways to wire things up, but I am curious to hear what you guys on the forum feel is the better setup.
Oh, and I am already running a wire from the ignition terminal on the fuse block to my electric choke. If the consensus is to run a ballast resistor, it will be easy for me to tap off of that line as an input to the ballast resistor.
Mainly just curious about what others have experienced with their setups.
You can't use the aftermarket system off the resistance wire.. You need straight 12 volts to it so find a direct 12 volt power source and by-pass the resistance wire.
The resistance wire when heated will drop the voltage.
Would it work to run a line from the ignition terminal on the fuse block to a ballast resistor, and then to the coil?
Personally, I'd want switch voltage...
So I'd find a power supply that is cut off when the ignition switch is turned off. You can't run the resistance wire, it drops voltage and the aftermarket distributor requires 12 volts...
Any recommendations on sources for switch voltage in a C3?
The ignition coil HAS been running off of the resistor wire and the car seems to operate fine. However, if by doing this I am sacrificing some performance then I obviously want to select a wiring scheme that is more appropriate.
Turbotrad- I switched from stock points to HEI distributor, connected to the stock lower voltage wire that went to the old distributor and wondered why the new HEI did not work properly. When I realized my mistake I ran a new wire to the IGN terminal on the fuse block to get 12 volts. Works fine now. You should be able to go thru the rubber grommet on the firewall to run the wire to the fuse block.
Turbotrad- I switched from stock points to HEI distributor, connected to the stock lower voltage wire that went to the old distributor and wondered why the new HEI did not work properly. When I realized my mistake I ran a new wire to the IGN terminal on the fuse block to get 12 volts. Works fine now. You should be able to go thru the rubber grommet on the firewall to run the wire to the fuse block.
Thanks for the suggestions. When it didn't run well what were the symptoms?
I faithfully followed the wiring diagram when installing that new wiring harness so all I really know recently is how the car runs when the coil/Mallory E-Spark module runs when powered from the harness itself.
It does currently work, but if a simple change like running a dedicated 12v line to the coil would create a noticeable difference then I obviously want to do that instead.
Here is photographic evidence that it is currently wired improperly.
During this process I did notice my yellow wire has some rubbing wear on the insulation so I might need to wrap some heat shrink over the spot and keep it more secure with a zip tie.
Last edited by Turbotrad; May 12, 2019 at 10:27 AM.
You can leave the resistance wire connected and just run a 12 gauge bypass wire directly from the IGN terminal on the fuse block to the positive on the coil. You say you have the IGN terminal going to an electric choke but a better idea for your aftermarket choke is to tap into the yellow wire at the wiper motor (green, yellow and blue wires at plug) as it is 12V and more important, is fused and is on anytime the ignition switch is in the on position. You do not want an un-fused wire going to a heated coil.
Last edited by CanadaGrant; May 12, 2019 at 10:25 AM.
You can leave the resistance wire connected and just run a 12 gauge bypass wire directly from the IGN terminal on the fuse block to the positive on the coil. You say you have the IGN terminal going to an electric choke but a better idea for your aftermarket choke is to tap into the yellow wire at the wiper motor (green, yellow and blue wires at plug) as it is 12V and more important, is fused and is on anytime the ignition switch is in the on position. You do not want an un-fused wire going to a heated coil.
Thanks! That's a great idea and it makes sense. I appreciate the help!
I have a stock distributor running the Mallory Infrared optical module in my 69 and have been using it for decades. I have the stock wiring that uses the resistor wire and have no problems hitting 6,500 rpm.
Turbotrad- "When it didn't run well what were the symptoms?" The car started, but sputtered, mis-fired and had no power.
Ah I see, yeah I would definitely classify that as not running well!
I currently have a lack of power issue, but I'm certain it's due to sub-optimal timing, and poor accelerator pump circuit tuning (it's close, but likely one nozzle from being perfect).
In my adventures to tune the distributor and vacuum advance I noticed my ignition wiring setup and that led to me starting this thread. The previous owner installed a ballast resistor on the firewall. I assume they needed it because they did not utilize the Mallory coil with the higher total resistance, any maybe also because the engine wiring harness was older so who knows what condition the resistor wire was in at the time.
Since I switched to the Mallory coil (#29219), AND replaced the engine wiring harness, I no longer need the ballast resistor. I might remove it clean up my firewall setup, or I might keep it and run a dedicated 12v line to it and the coil to bypass the resistor wire. Haven't decided. Looks like either way will work (the engine wiring harness resistor wire has been working).
Last edited by Turbotrad; May 12, 2019 at 06:38 PM.
Resistor wire Vs. Ballast Resistor
