Pertronix flame thrower upgrade

[Ryunker]

So this weekend plan to upgrade the ignition in the car, current ignition system has always been problematic. AutoZone distributor been replaced under warranty five or six times, power to the coil, is less than battery voltage, as I tapped electric choke in there.

All that aside, have a decent Motorcraft distributer, Pertronix flame thrower three kit, coil and their plug wires here, in storage box ready to go. Going to get power from "the idle stop solenoid" circuit.

Question is, do the relay thing and find battery power under the hood somewhere? Or is there enough juice on the idle stop solenoid circuit to power the new ignition system?

(Photo just for fun)

 

[timachone]

Switched 12V Power is the key.

Both solutions would be fine.

I did the relay thing, activated by a separate wire from the 20 amp fused ACC terminal on the fuse panel. From the relay I switch the Pertronix 1 and the electronic choke of my carb.

 

[timachone]

Photos...

 

[Stanglover]

On mine, (and I wish I hadn't) I cut out the pink resistor wire at the plug under the dash, and replaced it with 10 gauge ( or was it 12 gauge?) wire directly to the coil. This bypassed the old circuit and provided a full keyed 12 volts directly to the coil and Pertronix III that was originally installed after the motor rebuild. That kit was provided by the engine rebuilder that I'm sure he had laying around. He ought to have left it on the shelf!
The Pertronix Ignitor III at that time, 2012, proved to be a total piece of garbage. Electronically probably very good, but for the Ford application with 2 plates, the "bearing" if you could call it that between them, was an engineering disaster. I returned it to Pertronix and they replaced it with an Ignitor II and matching coil under warranty and I've had no problem since.
Hopefully by now Pertronix have re-engineered the "bearing" between the plates so it doesn't fail within a couple of months. As you say you have the kit on the shelf, yes, I'd try it, but if the timing start to wonder or it starts to run unevenly, the PIII could be the problem.
Anyway, moving on. if I were to do it again, I'd go with the relay approach and save the hassle of bypassing the old resistor ignition circuit on my 71.
Timing the Motorcraft distributor will likely be your next question. There has been lots posted on that subject.
Good luck.

 

[Hemikiller]

Idle stop solenoid feed has a 14A fuse in the fuse box, so you should be fine powering both off that circuit.

 

[midlife]

On mine, (and I wish I hadn't) I cut out the pink resistor wire at the plug under the dash, and replaced it with 10 gauge ( or was it 12 gauge?) wire directly to the coil. This bypassed the old circuit and provided a full keyed 12 volts directly to the coil and Pertronix III that was originally installed after the motor rebuild. That kit was provided by the engine rebuilder that I'm sure he had laying around. He ought to have left it on the shelf!
The Pertronix Ignitor III at that time, 2012, proved to be a total piece of garbage. Electronically probably very good, but for the Ford application with 2 plates, the "bearing" if you could call it that between them, was an engineering disaster. I returned it to Pertronix and they replaced it with an Ignitor II and matching coil under warranty and I've had no problem since.
Hopefully by now Pertronix have re-engineered the "bearing" between the plates so it doesn't fail within a couple of months. As you say you have the kit on the shelf, yes, I'd try it, but if the timing start to wonder or it starts to run unevenly, the PIII could be the problem.
Anyway, moving on. if I were to do it again, I'd go with the relay approach and save the hassle of bypassing the old resistor ignition circuit on my 71.
Timing the Motorcraft distributor will likely be your next question. There has been lots posted on that subject.
Good luck.

It has always puzzled me why it is recommended to use a 10 or 12 gauge wire replacing the pink resistor wire. The current going to the coil should be on the order of 10 amps or so (maximum), so a 16 gauge wire should be more than sufficient to do the job with a Petronix. With points, it is possible to have a near short-circuit if the key is left in RUN and the points are closed, such that full voltage provided goes to ground.

 

[Stanglover]

It has always puzzled me why it is recommended to use a 10 or 12 gauge wire replacing the pink resistor wire. The current going to the coil should be on the order of 10 amps or so (maximum), so a 16 gauge wire should be more than sufficient to do the job with a Petronix. With points, it is possible to have a near short-circuit if the key is left in RUN and the points are closed, such that full voltage provided goes to ground.

Midlife,
I knew I wasn't loosing it. See scan below under "instructions" for the Pertronix Ignitor III. It does say to use a 12 gauge wire. You may need to enlarge the jpg to see it clearly.
This is the one first installed on my car as mentioned in my post above.
For Ignitor's I or II, it is not mentioned to use that gauge wire and indeed both can be run on the resisted circuit, but not recommended.

 

[tony-muscle]

It has always puzzled me why it is recommended to use a 10 or 12 gauge wire replacing the pink resistor wire. The current going to the coil should be on the order of 10 amps or so (maximum), so a 16 gauge wire should be more than sufficient to do the job with a Petronix. With points, it is possible to have a near short-circuit if the key is left in RUN and the points are closed, such that full voltage provided goes to ground.

Agree. Maybe just in case you want to wrap the wire around the car from the engine bay to the ignition

Amps @ 13.8 Volts​	LENGTH OF WIRE American Wire Gauge (AWG)​
​	0-4 ft.​	4-7 ft.​	7-10 ft.​	10-13 ft.​	13-16 ft.​	16-19 ft.​	19-22 ft.​
0-10​	16-ga.​	16-ga.​	14-ga.​	14-ga.​	12-ga.​	10-ga.​	10-ga.​
10–15​	14-ga.​	14-ga.​	14-ga.​	12-ga.​	10-ga.​	8-ga.​	8-ga.​
15-20​	12-ga.​	12-ga.​	12-ga.​	12-ga.​	10-ga.​	8-ga.​	8-ga.​
20-35​	12-ga.​	10-ga.​	10-ga.​	10-ga.​	10-ga.​	8-ga.​	8-ga.​
35-50​	10-ga.​	10-ga.​	10-ga.​	8-ga.​	8-ga.​	8-ga.​	6 or 4-ga.​
50-65​	10-ga.​	10-ga.​	8-ga.​	8-ga.​	6 or 4-ga.​	6 or 4-ga.​	4-ga.​
65-85​	10-ga.​	8-ga.​	8-ga.​	6 or 4-ga.​	6 or 4-ga.​	4-ga.​	4-ga.​
85-105​	8-ga.​	8-ga.​	6 or 4-ga.​	4-ga.​	4-ga.​	4-ga.​	4-ga.​
105-125​	8-ga.​	8-ga.​	6 or 4-ga.​	4-ga.​	4-ga.​	4-ga.​	2-ga.​
125-150​	8-ga.​	6 or 4-ga.​	4-ga.​	4-ga.​	2-ga.​	2-ga.​	2-ga.​
150-200​	6 or 4-ga.​	4-ga.​	4-ga.​	2-ga.​	2-ga.​	1/0-ga.​	1/0-ga.​
200-250​	4-ga.​	4-ga.​	2-ga.​	2-ga.​	1/0-ga.​	1/0-ga.​	1/0-ga.​
250-300​	4-ga.​	2-ga.​	2-ga.​	1/0-ga.​	1/0-ga.​	1/0-ga.​	2/0-ga.​

 

[mrgmhale]

I tend to agree with HemiKiller re: using the Throttle Position Solenoid (TPS) wiring as an ignition coil source for a kit that needs you to eliminate the lower voltage bypass circuit (pink wire). I have a video (of course) showing more info on that subject at:



As for you having used the Electric Choke Heater circuit, if you used the factory Circuit #4 (White wire with a Black Stripe), please be aware that is a circuit like no other circuit on those old Mustangs. The electric choke on those oem stock carburetors were powered through Circuit #4 from the alternator's Stator terminal, which outputs 1/2 Alternator power (6-7 volts) of AC current, not DC current like the rest of the car's electrical systems. If you have an aftermarket carburetor with an electric choke it is possible (but not likely) someone may have tapped into a different circuit to provide 12 volts of switched current, but I would not count on that having happened I often see where replacement carburetors have had the original Circuit #4 wire used on their electric choke terminal, despite the fact the aftermarket cars "require" a 12 volt DC switched circuit., The Circuit #4 will work, kind of, although the choke will open slower and later than desired.

If you do not see/have a TPS circuit #640 wiring lead (71 or 72) another place you can get 12" switched power is from the Windshield Wiper Motor Circuit #63 (Red wire, no tracer/stripe). I have another video showing how to tap into that circuit at:

 

[YellowHorse]

Midlife,
I knew I wasn't loosing it. See scan below under "instructions" for the Pertronix Ignitor III. It does say to use a 12 gauge wire. You may need to enlarge the jpg to see it clearly.
This is the one first installed on my car as mentioned in my post above.
For Ignitor's I or II, it is not mentioned to use that gauge wire and indeed both can be run on the resisted circuit, but not recommended.

Did you or anyone else wired 12v directly to Petronix ignator (ingnator 3)?

Yesterday I learned that you should not feed 12v power to the coil, as it will wreck tachometer with Ignator 3.

Also does coil resistance makes a difference for tachometer proper operation and lifespans? I curently have 0.6ohm coil, which should be 0.32 ohm with Ignitor 3.

 

[Stanglover]

Did you or anyone else wired 12v directly to Petronix ignator (ingnator 3)?

Yesterday I learned that you should not feed 12v power to the coil, as it will wreck tachometer with Ignator 3.

Also does coil resistance makes a difference for tachometer proper operation and lifespans? I curently have 0.6ohm coil, which should be 0.32 ohm with Ignitor 3.

Sorry, I can't answer your question as I don't have a factory tach car.
I do have 12V directly to the coil though, which is a Flame Thrower II. Everything works fine, no issues.
Personally, I'd still ditch that PIII unless it's in a Pertronix distributor. Again, based on a bad experience I had with a PIII.

 

[YellowHorse]

Sorry, I can't answer your question as I don't have a factory tach car.
I do have 12V directly to the coil though, which is a Flame Thrower II. Everything works fine, no issues.
Personally, I'd still ditch that PIII unless it's in a Pertronix distributor. Again, based on a bad experience I had with a PIII.

Car came with Petronix flamethrower distributor and Ignitor 3. I want to see if there is wiring solution to be able to use stock tachometer with curent set up before throwing money at it.

Also I will need to figure out how it is curently wired - check how ignator is fead.

 

[Stanglover]

Car came with Petronix flamethrower distributor and Ignitor 3. I want to see if there is wiring solution to be able to use stock tachometer with curent set up before throwing money at it.

Also I will need to figure out how it is curently wired - check how ignator is fead.

Other people's wiring can be very confusing. I had my share to contend with too.
The electrical experts should be able to help. And yes, I do now recall you saying you had the Pertronix dizzy, so I'm thinking that should be fine........... maybe!