Converting to a Pertronix ignition in my distributor, the instructions indicate to omit a resistor wire in the wire going to the + side of coil. Which wire is it? I am thinking the cloth braided wire, but not sure.
There are two wires going to the + side of the coil. One is the 6 volt resistor wire that comes from the bulkhead connector. It is usually a black wire with silver looking strands in it. Your braided wire is probably the one. The other wire is a 12 volt yellow wire coming from the 'R' terminal on the starter solenoid. That gives 12 volts to the coil only in 'START' position for easier starting. Once running the resistor wire only gives 6 volts so the points don't burn up. Most electronic ignitions want a full 12 volts to operate properly. You can cut the resistor wire at the bulkhead connector and splice in a heavy gauge 12 volts wire, or unplug the connector and re-pin it for the 12 volt wire.
Thinking about doing the same change over to Pertronics. Interesting that my 69 does not use the resistor wire at the coil or the starter. Had the car since ‘76 when it had the original engine etc. Assuming the wiring was as original, the resistance is done in the harness somewhere. If so, instead of tearing into my harness I’m thinking about using a relay to get the 12 volts to the coil and using the original coil power wire to activate the relay. Have used the resistor wire to activate relays in the past to activate electric fuel pumps and electronic ignitions on other projects. The resistor wire did work to activate the relay. Still thinking, let us know what you come up with!
I plan to use a temperature gauge instead of using the idiot light sensor, so the lead to that would be 12V? If so, I could tap the 12V positive there, and clip the lead at the bulkhead?
The Pertronix is a good unit for a couple of reasons. For one thing, it all fits under the stock cap so it looks like you are still using the original points system. The other thing is when you use something like the GM HEI unit [my favorite] the cap is too big and you must massage the firewall for clearance. Points are needed for car show originality credit but for everyday operation who in their right mind wants to still use a system that degrades quickly? As for the power wire, electronic ignition wants a fat 12 volts and that means using a heavy gauge wire that can carry the load. I like to use at least 8 or 10 gauge wire. The small gauge used for the idiot lights is probably not a good idea. I kept my idiot lights even though I had a mechanical gauge set because you aren't watching the gauges all the time. The idiot light is good backup and gets your attention fast. Using a relay activated by the resistor wire is a good idea. Just be sure the minimum voltage to activate the relay is below 6 volts. When I was searching for relays to power my convertible top I found a wide range of minimum and maximum voltages. A relay that needs at least 8 volts will not work for you. You could also interrupt the ignition wire at the ignition switch under the dash. It doesn't become a resistor wire until it passes the bulkhead connector. Run the heavy gauge ignition wire through a grommet in the firewall or re-pin the bulkhead connector.
Yes, as long s it is ignition switched, except that you may accidentally share a circuit with something else that may reduce the amperage. You don't want the ignition reduced when you, say, turn the wipers on. It is best to run the wire right off the ignition wire at the key switch. On 1969 cars that switch moved down the column and is activated by a rod from the ignition key. You really want to try and keep your ignition voltage as 'clean' as you can.
The wire that comes off the ignition switch looks to be pink, according to the 1968 FSM wiring diagram. When they switched to HEI in 1975, the 12 volt coil wire stayed 'pink' all the way to the distributor. But be careful because there is also a downstream splice where another pink wire comes off that and goes to the fuse panel. That feeds 'ignition switched' power to various things and they also use pink wires. It is probably best to interrupt the ignition switched coil feed closer to the bulkhead connector. In the FSM it is cavity 'K'.
Is the pink/black stripe wire on the engine side or passenger compartment side? According to the FSM that should be on the engine side and it is the resistor wire. On my original 1968 car the resistor wire was black with silvery threads woven through it. It resembled a shoelace, not plastic covered. There is another pink wire going to the ignition switch but it has a double black stripe. On the engine side it becomes a black w/pink stripe. That goes to the horn relay. The FSM in '68 doesn't show the wire gauges but I would assume the pink wire is a heavy gauge. It feeds the fuse panel and all 'ignition switched' circuits which includes the distributor.
On the dash side the heavy gauge pink wire & a smaller gauge pink/double pink. On the engine side harness it is the wire shown in my pictures.. It is reproduction harness from M&H, so color of resistor wire appears to be different on mine.
a smaller gauge pink/double pink. So color of resistor wire appears to be different on mine.
You mean pink/ double black, right? Yes, the resistance wire is the woven cloth looking one. It is not a solid or braided copper wire, rather it is designed to only let 6 volts pass. The heavy gauge pink is the 'ignition switched' wire. So it looks like the factory ran the ignition off that fat pink wire while at the same time using it for all the other 'ignition switched' circuits. I guess that is OK since the coil wire eventually became 6 volts anyway. That is why I suggested running a dedicated 12 volt coil wire to the distributor for the electronic ignition. It's just makes good electrical sense. But if you could interrupt it right at the firewall that would probably suffice.
Absolutely. In fact guys do that so they can fabricate some sort of anti-theft device. I usually use a big toggle switch hidden up under the dash, but I have seen all kinds of ingenious things. One guy had it rigged so you had to have the manual shifter in reverse, the ashtray pulled out to an exact spot, and a button inside the console glove box pushed. That is extreme but you get the idea. Also remember that you will no longer need the yellow 12 volt wire that goes from the starter solenoid to the coil. It was only there to give 12 volts to the coil in 'Start' for easier starting. It is always best to rig your anti-theft device to the ignition circuit instead of the starter. You can reach up under the car with a big screwdriver and jump the starter "S" terminal to the 'batt' cable and bypass the kill switch and start the car. It is much harder to power the ignition if the hood is locked and you don't have access to the ignition wiring.
This is a pic of my original dash harness ignition switch plug showing the thick pink wire for ignition circuit. Can I cut my harness aprox 3 in. could I splice in my new feed there?
Yes, you can splice there. Looking in the 1968 FSM that wire goes to a splice farther down. That splice feeds the fuse panel for the ignition switched fuse so don't just cut it apart there. You can splice in your new wire that close to the ignition switch. If you do splice it I recommend soldering it. Strip away about an inch of insulation, wrap the new wire around the bare pink wire, solder, seal, and shrink wrap it. I use a product called MDR Liquid Lectric Tape for all things electrical. There are two kinds, solvent based and water based. The water based takes longer to dry but I feel it is tougher than than solvent based. This stuff is what I use on boats so you can be sure it will protect your wiring connections on the car.
