How to fit a Pertronix Ignitor 2 or 3 to a Shelby GT500KR??

[Flasheart]

I have read every forum post that contains the word 'Pertronix' and I am still not entirely clear if it can be done while keeping a functioning tach?

I am not an auto electrician but I can read the wiring diagrams.   Is there one best way to fit the PerTronix 2 or 3, with a higher output coil, and with full 12V, while maintaining tach functionality, and not starting a fire somewhere?

[69 GT350 Vert]

I did it with a pertronix 1 many years ago without splicing wires. I made a Y connector using various male and female bullet connectors.  I can't remember exactly, but I think I needed 2 12v sources from ignition switch under dash.  So i inserted the Y connector and ran 1 to tach, and 1 through firewall to pertronix.  Wasn't pretty, but out of sight.

[shelbydoug]

The wiring issue seems to stem from using a II or III. The Petronix 1 is compatible with the Ford Tach.



The simplest way to explain it is that the Petronix needs 12v run directly to it. The Ford yellow top will self destruct with that.

The simplest place to pick up a 12volt switched source or the Petronix is at the input to the tachometer inside the dash. You can get access to that by removing the radio and the ash tray assembly.

There is where you create a "y" splice. One going back into the tach input and the other to the red input wire into the Petronix. Don't run that wire to the plus terminal on the coil as the Petronix instructions say.

The plus terminal of the coil is going to only take two wires connected to it. One is the pink resistance wire running from the tach output wire. The other is the 12v red wire running from the starter solenoid I terminal.

The I terminal from the solenoid supplies 12 volts to the coil while the starter switch is in the "start" position, turning over the starter motor.

When the ignition switch is in the run position, and the engine running, the voltage reading at the plus terminal on the coil will be 6volts. If it is more, then replace the resistance wire. They can wear out with time.



The entire issue really is caused by the Ford tach that reads off of the plus terminal of the coil. Just about every other tach system on the planet reads off of the negative terminal.

This just has to do with the original Ford engineering design of essentially just "splicing in" the tach into the electrical system of the car to reduce major wiring redesign of the standard ignition system.

We have to live with that peculiarity.



I don't have a Petronix II or III, but am informed by those that do that those are the ones that need a wiring adapter to make the tach function. I personally can't confirm that.



In all honesty, there isn't much advantage to using a Petronix v. stock points. It does give you better dwell characteristics but there isn't much advantage to that. Even the race Cobras and GT40's used points and yellow top coils.

A standard set of points should easily give you 30,000 miles before needing replacement which is a very simple thing to do even on the road if need be.

People are carrying spare Petronix units with them. Those two factors should suggest something to you right there?

[Royce Peterson]

Never used a Pertronix 3. The Pertronics 2 (or II) wires in exactly the same as a Pertronix 1 and has zero effect on the tachometer if you follow the directions and use the original yellow top coil or any coil with exactly the same resistance as a stock yellow top coil. 

I have read every forum post that contains the word 'Pertronix' and I am still not entirely clear if it can be done while keeping a functioning tach?

I am not an auto electrician but I can read the wiring diagrams.   Is there one best way to fit the PerTronix 2 or 3, with a higher output coil, and with full 12V, while maintaining tach functionality, and not starting a fire somewhere?

[2112]

Never used a Pertronix 3. The Pertronics 2 (or II) wires in exactly the same as a Pertronix 1 and has zero effect on the tachometer if you follow the directions and use the original yellow top coil or any coil with exactly the same resistance as a stock yellow top coil. 

Are you gaining all the(claimed) performance with a stock Coil? What is the resistance of a Stock Coil?

[shelbydoug]

Never used a Pertronix 3. The Pertronics 2 (or II) wires in exactly the same as a Pertronix 1 and has zero effect on the tachometer if you follow the directions and use the original yellow top coil or any coil with exactly the same resistance as a stock yellow top coil. 

Are you gaining all the(claimed) performance with a stock Coil? What is the resistance of a Stock Coil?

Exactly what gain is there supposed to be with the Petronix? What did J.C.Whitney claim it to be?

[2112]

Never used a Pertronix 3. The Pertronics 2 (or II) wires in exactly the same as a Pertronix 1 and has zero effect on the tachometer if you follow the directions and use the original yellow top coil or any coil with exactly the same resistance as a stock yellow top coil. 

Are you gaining all the(claimed) performance with a stock Coil? What is the resistance of a Stock Coil?

I thought a Hotter ignition (spark) and therefore less fouling of plugs.

I don't care one way or the other, just curious.

Exactly what gain is there supposed to be with the Petronix? What did J.C.Whitney claim it to be?

[shelbydoug]

I personally see no difference in performance.

The original Ford system of points is just as good.

There is only one ignition system that I know of that fires and cleans up fouled spark plugs. That is made by a company called Pantera Electronics.

In that system they recommend not using a "coil in a can" but it will work with one.

https://www.youtube.com/watch?v=FYKRtOgDcFg&feature=youtu.be

[Royce Peterson]

I don't believe there is any noticeable difference in performance of the stock coil compared to the Pertronics ones but for the tach to work and be accurate the resistance of the primary side is critical. Here are the factory specifications.

Never used a Pertronix 3. The Pertronics 2 (or II) wires in exactly the same as a Pertronix 1 and has zero effect on the tachometer if you follow the directions and use the original yellow top coil or any coil with exactly the same resistance as a stock yellow top coil. 

Are you gaining all the(claimed) performance with a stock Coil? What is the resistance of a Stock Coil?