I just installed a Pertronix Module in my new 292 engine.  My car originally had a ballast resistor.  I am using a stock 1957 Ford distributor.  The Pertronix instructions say to install the red wire to the hot side of the ballast resistor and the black wire to the distributor side of the coil. I am using the coil that came with my car.  I don't know if it's a six volt coil, but the engine ran fine before the tear down.  I wired the Pertronix module as instructed, but I haven't tried to fire the engine yet.   

I Googled the ballast resistor and it's purpose is to extend the life of the points by reducing the voltage when the car is running.  I don't have points now.  Why do I need the ballast resistor?  I don't remember ever using it before.  Why can't I ditch it?

If You change the Coil to Flamethrower 11 with .06 built in Resistance You can do away with the Resistor and full 12 Volts to Coil. With stock Coil U need the Resistor to protect the Coil.If U run 12 volts to without Resistor it will work but Coil will fail at some Point.

  

I have a Pertronics I module in my 57 distributor.  Do you know the Pertronix stock number of the coil I can use without the ballast resistor?  Thanks!

Answers to your questions are provided in the instructions:
http://www.pertronix.com/docs/instruction-sheets/1281.pdf



Lawrenceville, GA

The ignition ballast or resistor wire does reduce the voltage through the primary circuit, but the intent here is actually to reduce the current flow (amperes).

Points don't really care about voltage, but they will burn up if the current flow is too high. A running engine draws maybe 2 or 3 amperes through the coil and points and associated wiring, ignition switch etc. They can't handle more than this.

Notice too that a non-running engine with the key in the RUN position - draws more current - about 4 or 5 amperes. The coil in this situation will get smoking hot because of the excessive current, and may well spooge itself all over the engine bay if left for more than a few minutes. An ignition coil is not "on" all the time when running, a V8 has about a 66% duty cycle. So the overall current through the primary circuit is lower when running.

The OEM split the resistance into a divider network so as to provide for a hotter spark during engine start. About a 1.4 ohm coil, and about a 1.4 ohm ballast wire. Total about 3 ohms. The ballast resistor is bypassed briefly during starting, then, when the key is returned to RUN, the ballast is in circuit to drop the voltage (current flow) to safe levels during operation.

The Ignitor module can handle more current than the points can, but it too, has a limit. The basic 1281 unit is limited to about 8 amperes. This is why the instructions caution to use an ignition coil with at least 1.5 ohms resistance. No extra ballast resistor is neither necessary nor desirable provided the coil itself has a resistance of 1.5 ohms

Ohms Law and a pencil & paper will tell you what the current flow is through any ignition system and any combination of parts.

Usually where people run into trouble is installing an ultra-low resistance coil designed for their higher end modules, coupled with an earlier type Ignitor like the 1281 module, they are not compatible.

Pertronix makes several coils, some with as low as 0.6 ohms primary resistance. This will smoke the basic 1281 module used in our Fords quickly.

Those coils are to be used with the Original Pertronix 1. Remove Ballast Resistor as indicated in Instructions. I have Pertronix 11 which uses Flamethrower 11 Coil without Resistor. The Coil to use depends on which Pertronix you are using. They need full 12 Volts to give maximum Performance. You can also Contact Pertronix for Tech Assistance.

  

I have a Pertronix 1281 Module in my 57 distributor.  I currently have the ballast resistor connected.  After I have fired the engine and things settle down a bit I will contact Pertronics Tech Support to get their advice on a coil.  Thanks.

I installed a Pertronics ll in my 56 6 yrs ago using their coil and a 57 dist. I had read online of complaints concerning coils, theirs and other brands, prior to installing the unit. I choose to use my stock ballast resister. I called them concerning doing this (they are local to me in San Dimas, Ca.) the tech said its OK, you just won't have quite as hot a spark.
it has performed flawless, never failed, qwik starts cold or warm. I've checked the plugs twice in that time and did not change them. I'm glad I installed their unit after 2 failed condensers.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

That is correct as far as U can leave the Resistor in. Just cuts down Voltage from 12 to about 9.6-10 Volts. I had a Pertronix 11 and the Flamethrower Coil on the 56 I sold this Summer  with no Resistor for over 10 Years. Never had a problem with either the Coil or the Unit itself. One of the first things I did on my recent Purchase was to install 57 Type Distributor, Pertronix 11, and the correct Flamethrower Coil( with no Resistor).

  

Like oldcarmark, I have a Petronix II and their coil.  No resistor per their instructions.  While I haven't had it a long time, I have made a very long trip (6,3000 miles) with it along with some shorter trips and haven't any problems.


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