Question on Ballast Resistors

[badvs3vil]

Hello everyone,

I just had a quick question on ballast resistors. Mainly if I need one or not. I changed out my coil this weekend and it got me thinking about it. Currently, I am using a ballast resistor. Voltage drops down to around 6v after starting up.

However, here is the ignition system I have and my new coil.

Proform 66993: Electronic Distributor Conversion Kits for Chrysler/Mopar Big Blocks "B" 361-400 - JEGS

MSD Ignition 8202: Red Blaster 2 Coil For MSD Ignitions - JEGS

I assume if I didnt have the resistor in place, I would get a hotter spark? Any reasons with my setup to not run without one?

Thanks for the help.

 

[Big_John]

Hello everyone,

I just had a quick question on ballast resistors. Mainly if I need one or not. I changed out my coil this weekend and it got me thinking about it. Currently, I am using a ballast resistor. Voltage drops down to around 6v after starting up.

However, here is the ignition system I have and my new coil.

Proform 66993: Electronic Distributor Conversion Kits for Chrysler/Mopar Big Blocks "B" 361-400 - JEGS

MSD Ignition 8202: Red Blaster 2 Coil For MSD Ignitions - JEGS

I assume if I didnt have the resistor in place, I would get a hotter spark? Any reasons with my setup to not run without one?

Thanks for the help.

The short answer is no, you don't want to run without one. You will probably fry the coil.

The long answer is the ballast resistor limits current after the engine starts. Because of less current (amperage), the voltage will drop under load (Ohm's law). For starting, the current isn't limited, which does give full current to the coil to help with starting. Let the key off to run and the current is reduced and that helps the coil live longer.

 

[badvs3vil]

The short answer is no, you don't want to run without one. You will probably fry the coil.

The long answer is the ballast resistor limits current after the engine starts. Because of less current (amperage), the voltage will drop under load (Ohm's law). For starting, the current isn't limited, which does give full current to the coil to help with starting. Let the key off to run and the current is reduced and that helps the coil live longer.

Thanks John

I guess what I don't understand that even on that MSD page, it says you only need a resistor if you are running points.

• Improved output coil for electronic, Point, Blaster or MSD 5, 6, and 7 Series Ignitions (ballast resistor required for points)

 

[Big_John]

Thanks John

I guess what I don't understand that even on that MSD page, it says you only need a resistor if you are running points.

The MSD units don't need a ballast resistor because they limit the current internally.

You are mixing directions between the ProForm and the MSD. Different animals.

I don't run one with my Pertronix II in my Barracuda.

 

[badvs3vil]

Stuff like this make things confusing...

 

[Big_John]

Stuff like this make things confusing...

View attachment 601326

OK, what does the ProForm instructions say? I'll bet it says it needs a ballast resistor and that's your answer.

 

[badvs3vil]

OK, what does the ProForm instructions say? I'll bet it says it needs a ballast resistor and that's your answer.

Doesnt say on their site, maybe ill give them a call and see what they say.

https://www.proformparts.com/produc...uum-advance-fits-chrysler-361-383-400-engines

 

[Big_John]

Doesnt say on their site, maybe ill give them a call and see what they say.

https://www.proformparts.com/produc...uum-advance-fits-chrysler-361-383-400-engines

I looked it up with the Jeg's link for the ProForm ignition. Just click on instructions.

https://www.jegs.com/InstallationInstructions/700/778/778-66991_66993_66995.pdf

Looks like they say use with ballast resistor to me.

The Motor Trend article is just plain wrong. There are some electronic ignitions that use ballast resistors and some that don't. Example is the 1973 Chrysler factory electronic ignition that used a double ballast resistor, Your ProForm stuff is a clone of that system.

If you really want to not use a ballast resistor, junk the ProForm Chinese crap and get a good rebuilt Mopar electronic distributor, connect a GM HEI unit and the cherry on top would be a Ford E-coil . That combo doesn't need a ballast resistor, will give you all the hot spark you'll ever need and won't break the bank.

 

[badvs3vil]

I looked it up with the Jeg's link for the ProForm ignition. Just click on instructions.

https://www.jegs.com/InstallationInstructions/700/778/778-66991_66993_66995.pdf

Looks like they say use with ballast resistor to me.

The Motor Trend article is just plain wrong. There are some electronic ignitions that use ballast resistors and some that don't. Example is the 1973 Chrysler factory electronic ignition that used a double ballast resistor, Your ProForm stuff is a clone of that system.

If you really want to not use a ballast resistor, junk the ProForm Chinese crap and get a good rebuilt Mopar electronic distributor, connect a GM HEI unit and the cherry on top would be a Ford E-coil . That combo doesn't need a ballast resistor, will give you all the hot spark you'll ever need and won't break the bank.

Awesome advice John,

That's my main issue, I really don't know what options are out there for me. So thank you for that. I am new to classic cars.

 

[commando1]

Example is the 1973 Chrysler factory electronic ignition that used a double ballast resistor

And why did they need to do that?

 

[badvs3vil]

And why did they need to do that?

Hell mine still has it.

 

[Big_John]

And why did they need to do that?

The dual ballast system is so convoluted that it's really hard to wrap your head around it.

This is a quoted answer to that question. He explains it better than I can and I had to read it a half dozen times to start to understand.

One side of the resistor supplies the COIL and the other side supplies the ECU. THAT is the half that was deleted. The coil side has never changed so far as the circuit. IN FACT if the ECU goes bad, you can pull the ECU connector, drop in an old points distributor, hook the dist. to the coil NEG and if the ECU was the only problem, it will run

When you START the car with a 4 terminal ballast, "things are a trick." There is no "ignition run" power during start, the coil PLUS is powered through the ballast bypass (brown, IGN2) circuit. So the power BACKFEEDS through the resistor to power the ECU during crank. VERY POOR DESIGN in my opinion

Here is the circuit. The "ignition run" at lower right is DEAD during cranking. Only power to the circuit comes from "Ignition 2" pink in the diagram

Current flow from coil is from ECU ground, through box switching transistor, to coil NEG and through coil, out coil + and back to battery through the pink "ign 2"

Box circuit is from ECU ground, out pin 1, through resistor from right to left lower section, out resistor and back to battery on pink

Other section is s from ECU ground, out pin 3 (blue) to top section of resistor, through top section from left to right, through bottom section from right to left, and back to battery on pink.

This is "properly described" as neg to pos electron flow

 

[Big_John]

Hell mine still has it.

View attachment 601351

Pull the connector on the ECU and count the pins. If there's 5, you need the dual resistor. If there's 4, you just need the single.

Are you sure that's a ProForm unit? That wiring setup has early Mopar Performance written all over it.

 

[badvs3vil]

The dual ballast system is so convoluted that it's really hard to wrap your head around it.

This is a quoted answer to that question. He explains it better than I can and I had to read it a half dozen times to start to understand.


View attachment 601354

Yeah it was a pain when I rebuilt my car, without knowing much and having to fix all the wiring in mine.

I did find a YT video at the time that helped me get mine going back then.

 

[badvs3vil]

Pull the connector on the ECU and count the pins. If there's 5, you need the dual resistor. If there's 4, you just need the single.

Are you sure that's a ProForm unit? That wiring setup has early Mopar Performance written all over it.

Here is my actual purchase.

 

[badvs3vil]

Pull the connector on the ECU and count the pins. If there's 5, you need the dual resistor. If there's 4, you just need the single.

Are you sure that's a ProForm unit? That wiring setup has early Mopar Performance written all over it.

Its does have 4 pins and it did come with a single BR. But since my double tested fine and was already in place, I just left it and used it.

 

[bronze turbine]

This is a very interesting thread. Thank you Big John for the excellent explanation. Are the 5-pin ECUs still being made or are they obsolete? Seems to me if you install the 4-pin ECU you can just use the existing ballast resistor that came with the original points ignition? On a related matter, are the coils the same for points and ECU ignition? I've seen some documentation that says no, and some that says yes. I've also seen coils that are advertised as being compatible with both systems.

 

[Big_John]

This is a very interesting thread. Thank you Big John for the excellent explanation. Are the 5-pin ECUs still being made or are they obsolete? Seems to me if you install the 4-pin ECU you can just use the existing ballast resistor that came with the original points ignition? On a related matter, are the coils the same for points and ECU ignition? I've seen some documentation that says no, and some that says yes. I've also seen coils that are advertised as being compatible with both systems.

As I understand it, there are 5 pin versions still made. The 4 pin is "plug and play", it just doesn't have that extra pin and the extra side of the BR is just left in place. My '70 300 was wired like that when I got it and I just eliminated that part of the wiring.

The new 5 pin ECUs, so I'm told, were in response to the guys that asked where the 5th pin was on their new ECU. That may or may not be true...

The real difference in coils for our application is the primary resistance. Somewhere, there has to be a reliable reference to what coils work with the Mopar Perf ignition and its clones. IIRC, 1.5 to .7 ohms being the ones that work the best. I do know that generally speaking, the points ignition will use a 3 ohm coil. The lower the primary resistance, the more current and the better the output. The points need a higher resitance primary to keep from burrning out.

That said, we've all seen whatever coil is handy used with the Mopar electronic and they work... It's just which coil is the better choice.

 

[badvs3vil]

So I called Proform just now. They answered quick and was super helpful.

They said having a ballast resistor has nothing to do with their Distributors. It all comes down to the coil. And in my case with a MSD Blaster 2, it will handle 12v no problem.

He told me to remove the resistor and send it.

LOL

 

[Big_John]

So I called Proform just now. They answered quick and was super helpful.

They said having a ballast resistor has nothing to do with their Distributors. It all comes down to the coil. And in my case with a MSD Blaster 2, it will handle 12v no problem.

He told me to remove the resistor and send it.

LOL

If they actually said "voltage" instead of amperage or current, I wouldn't trust anything they said. If you measure the voltage with no load at the ballast resistor, it will be 12 volts. Put a load on it and the voltage will drop. Ohm's Law.

But, they are 100% right that their distributor doesn't make a difference. And that coil might be fine... I don't know... The MSD instructions are a little unclear with other ignitions. They say "points or stock" and to me, that ignition you are using is the same as a stock mid 70's Chrysler ignition.

If you pull the BR, just do yourself a favor and carry a spare ignition coil.