Saltshaker, besides being too much current through the coil and points as stated above with 12 volts, there is one other aspect of the 12 volt design. The coil is actually designed to function on aprox. 6 volts so when the resistor is bypassed while the engine is being cranked, the coil will still have close to it's designed full voltage.`When the key is released to the run position, the resistor is back into the circuit thus reducing the current through the primary ignition circuit once again. 

64F100 57FAIRLANE500

The voltage system puts out too much power for the coil and points, thereby resulting in premature wear and failure of the coil and points, if a ballast resistor isn't used. 

Can anyone tell me exactly why a resistor is used in a Kettering (points) ignition system?

Thanks 55. Took me a while to find the diagram you're referring to on their site. I was looking at the distributor info they had under the "ignition" tab, and that wasn't there. 
Glad you're using your free time wisely! 

Marc, look up your distributor on TSP's website. You'll find that it requires a full 12v, and the ballast resistor should be bypassed. If you look at the diagram, you'll find two numbers for their coils, the difference of which is that one has male terminals, the other female. I looked up part no. JM6928R, which just happens to be sold by Summit. It's rated 45,000 volts (high output), and the primary resistance is 0.700 ohms. 

I guess I must have more free time than you, being retired for 12 years. 

... i know i am going to regret this ...

The thing showed up today, and the paperwork says....

Surprisingly little. 
Just an admonition to use a "high output coil", and a few advance charts depending on what springs you use. Checked the box a couple of times to make sure I didn't miss anything.
Their office is closed now so I left them a little love note to ask what they recommend. We'll see what they come back with. 

Pertronix ll & lll Ignitors, TSP/CRT, and other electronic distributors do not use a ballast resistor and require a coil that's rated less than one ohm for V8 applications. If the coil you're considering is rated 0.4-0.6 (doesn't have to be exactly 0.6), you should be good to go. 

As Ted stated, a full 12v needed when eliminating the ballast resistor. 

Again, all of this information, with the exception of whether to use an oil-filled or epoxy-filled coil, should be found in the instructions for the Pertronix Ignitors or any aftermarket electronic distributor.

The Pertronix II does not require a resistor.  I don't know what coil ohm rating they require.  I used their coil so I didn't have to worry about that.  Not sure on the Pertronix III if a resistor is required.  I have my coil laying down.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

... i know i am going to regret this ...

PREVIOUS QUOTE -

"I think you'll find that the instructions state not to use a coil resistor with a 0.6 ohm coil as Ted stated. The Pertronix l Ignitor requires a 1.5 ohm coil and a ballast resistor. In either case, there is no recommendation for either oil-filled or epoxy coil."

INTERNAL COIL RESISTANCE is being described, not external supply voltage - 

       

The PERTRONIX 40111 Coil Is Epoxy Filled
https://pertronixbrands.com/products/pertronix-40111-flame-thrower-coil-40-000-volt-1-5-ohm-black-epoxy

____________________________

By all means, read the instruction sheet for your TSP/CRT or any other electronic distributor. I think you'll find that the instructions state not to use a coil resistor with a 0.6 ohm coil as Ted stated. The Pertronix l Ignitor requires a 1.5 ohm coil and a ballast resistor. In either case, there is no recommendation for either oil-filled or epoxy coil.