is it needed with any kind of electronic ignition? thanks

yes and no

Depends on which specific electronic system you are running.

No its not. I use MSD Pro Billet distributer in my GTX without ECU or ballast. Everything is in the distributer

So what you mean is your using one of the new all in one MSD distributor that doesn't use a outside ECU, correct Just like the old Mallory Unilte distributors, correct
OP, check with the company who makes the kit or ECU your using to get it correct
As already pointed out not all kits or ECU are the same when it comes to what is needed to make them live on the street

Exactly what Cab and SuperC wrote.
The ballast resistor is a common method to control the current through the coil by reducing voltage. The amount varies a little with temperature (on purpose).
However some electronic ignitions use other means to control the current through the coil.

Chrysler used a second ballast resistor to limit current to the ECU. Later versions don't need this.

Yes sir that's correct. The distributer is an all in one and no ballast required. Its not new. Been in my car since 2008

Do you have a particular setup in mind or that you are considering adding/changing?

This is correct. It depends on the ign system which many times means which coil and ECU is also used. Most units that have everything in the dist like GM HEI use a simple 12 volts to feed it. But some electronic units with separate ECU units may use a ballast. The factory Mopar electronic ign used a ballast and so did the factory Ford units for some years when they first came out around 1975. I believe Ford called theirs Dura-Spark and it still used a resistance wire in the wire harness to the primary side of the coil. Also most GM and Ford point systems used a resister as they had a resister wire in the primary wire harness as most think Mopar were the only ones to use a primary resistance since Mopar used the ballast mounted on the firewall. But the Mopar ballast can change ohms a little by temp where I don't think the GM and Ford resister wire changed ohms with temp.


Bottom line is I don't think you need a ballast but your unit should have had some paper work to tell you what they call for. Most if not all MSD units do not need a ballast as the MSD box controls both sides of the coil since its a low speed multi-spark. I use the MP orange ECU and I don't use the ballast because I don't use a stock coil as I use the older Acell Super Coil which had a slightly different ohms then the stock dist so it has a different current draw in amps and don't overheat my coil or ECU. Good luck with yours , Ron

maybe a pertronics or mopar ecu. or the fbo unit.

My last one was an OE 70's black chebby HEI module/OE 70's Mopar electronic dist/furd full 12V TBI? coil that Dog put me on to (dirt cheap at Rockauto). Didn't have the truck long after that but I noticed it started instantly which it didn't before. EDIT this elims the ballast & the HEI is (or can be) mounted under the dist (both giving a cleaner firewall) & you can get a full 12V intended regular round coil (that furd one does look unsightly).

So I wonder how fast would it be if you put a ECU on it that doesn't retard the timing by 6-8* under load? I will guess and say it would run 10.50's at least.

It's pretty common knowledge that the Orange box retards timing under load starting at 3000 RPM and by 5200 it's retarded by at least 8*.

Orange boxes haven't been made by Mopar for close to 20 years and they are all Chinese copies, less than $5 from China.

There's a reason they specify: "Mopar Performance parts beginning with a “P” prefix are sold “as is” unless otherwise noted. This means that parts sold by Mopar Performance carry no warranty whatsoever."


Summit-No Longer Available
Jegs- No Listing
Mancini- No listing

Ever wonder why?

I checked my timing up to 5000 rpm and it is not retarding my timing at all. I bought my orange box around 1998. This same box and coil were on my sons Dart which ran 11.40's with this same MP orange box that I use on my 63. When he bought an MSD system I put on his Dart his Dart still ran 11.40's with the MSD. It started and ran the same with MSD as it did with this orange MP ECU and Acell coil.


I have heard some say the orange box can retard timing as higher rpm which is one reason I checked mine. And the fact my sons car ran as fast with this orange MP ECU as it did with the MSD ign.

Funny thing is at higher rpm (over 6000) a small amount of timing retard can help power at high rpm. I remember Bill Jenkins used to cut out a set of his ign points in the late 60's when he was still using points in his dist. He did this to retard the timing some in high gear as he had it on a switch to work only in 4th gear. But of course the Mopar ign ECU's are not supposed to retard any timing at higher rpm. I don't know when the MP ECU started being made by cheaper places or oversea's but it seems like many that complain about them have bought them in the last 10 to 15 years. My orange ECU is about 20 years old and still working good. I always carry a spare ECU in my car but have never used it. Ron

TFI coil, Robert.


Part of the appeal of the HEI/TFI combination is no ballast resistor needed. The modern coil is designed to take full battery voltage.

^^^ Noted

On or about 1955 cars went to 12V systems. And, all the cars made, up to say '70 had ballast resistors, or resistance wires.

Millions and millions of cars made and no one thought to up grade the coils to take 12VDC? Not parts manufactures, engineers at car companies, nobody?
All of them had insufficient coils that needed to be protected by a resistor.

But yet, you can take one of those coils, hook it up to an MSD, and blow enough energy out of it to make the old points spark look sick. And it will last forever? Huh?

I think the resistor is there to either protect the points, or some ECU's.

But, that is just my opinion, and I've stated it before.

The TFI and HEI systems have current limiting function built into the control module (ECU). That's why there is no resister in their OEM applications.



That's an exageration and misleading. All electronics have a delay in switching. At the speeds the crank is turning, this cumulative slew rate starts to show up as a slight loss of timing. This can be, and was, addressed in the distributor curve. The reason you're seeing it is because you're stopping the advance too early. When a distributor is 'all in' at 2000 rpm, then its going to show the delay of whatever box your using as the rpms climb from there. By 6000 rpm it will be measurable. So then you have to make a much faster ECU or one that anticipates the slew.

The easy way to do it is let the secondary spring slow the curve like Direct Connection did (and they weren't the only ones). If you made the FBO plate the other way around, shortening the inside of the slots, this would be a non-issue. Went through this on FABO with you or colleages a couple months ago.

CD ignitions, like MSD makes, work differently. Its not an uncontrolled 14 Volts. The input energy is still controlled. With a Capacitive Discharge I think of it more like sending a package of energy through the primary. The coil then acts like a transformer.

As far as last dates of use. Ballast resistors or equivalent were used on all cars and trucks until replaced by systems that used a different means to control power through coils. For GM, that was in the HEI module, around 1975. For Ford, that was the EEC IV introduced in 1983-4. That was the orignal application for the 'TFI coil'. That didn't mean the end. Many jeeps continued to use Ford's earlier Duraspark II systems (with resistance wire) at least though 1991.

All late ignitions get more energy out because you put more in it.

Measure your coil input on an MSD, its over 200+ volts (which is why they say don't put a meter on it [inductive type ok]). Again, more in, more out. Yet, no ballast resistor, and the coil lasts.

don't conflate voltage and current

more voltage means less current.

What did the ballast do? limit current.

What does more voltage mean? less current

Two ways to skin a cat.

Assuming you know what the cat is.

I usually agree with most everything you state Supercuda.

My opinion here, is there is no need to limit anything to the coil, or we'd be building better coils.

These high energy ignitions are high energy because we are putting more in, and getting more out. That's all.

I used to teach electronics, real electronics. Magnetism, transformer action, induction are just some fascinating topics.

Off topic, but part of magnetism, "is aluminum affected by magnetism?" Yes, its repelled. EVERYTHING is affected by magnetism.

And its magnetism that makes a coil work. That concludes todays topics for me.