Question on Ballast Resistors

[badvs3vil]

Ha, I also emailed them but I didnt think their email worked so I called. Here is the answer I got back from the email.

 

[CarBrokeGuy]

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.

Big_John I'm going to disagree with you in part. The sole purpose of the ballast resistor is to drop the voltage so the points don't burn. If you no longer have points you no longer need the resister.

 

[CarBrokeGuy]

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.

Big_John I have to disagree with you. The sole purpose of the ballast resistor is to reduce the voltage to the points so they don't burn up.

 

[Big_John]

Big_John I'm going to disagree with you in part. The sole purpose of the ballast resistor is to drop the voltage so the points don't burn. If you no longer have points you no longer need the resister.

Number one, it reduces current, not voltage. The voltage does drop because of the load, but without load the voltage doesn't drop. This is Ohm's Law... Basic electrical stuff. Google it. Effectively, under load, it does reduce voltage so many sources do say "voltage reduction".

I'll agree that one of the things that the ballast resistor does is lower the current flow, or amperage through the points, if you have points that is. Since the OP doesn't have points, that's out of context here.

It does reduce current flow to the primary side of the coil. Actually, since it's in series, it effectively increases the primary resistance. Remember, Chrysler used it in their earlier electronic igntion to reduce curreent to the coil AND the ECU. No points there...

But in case you don't believe me... Here's some reading I picked at random. https://www.pepboys.com/auto-care/diy/parts-guide/ballast-resistor This one looks good because it explains what a ballast resistor is and other uses. https://www.electrical4u.com/ballast-resistor/

Here's even Uncle Tony explaining it. It will start about a minute in to eliminate some nonsense.

 

[badvs3vil]

I called Holley this morning and spoke to MSD. He said that the Blaster 2 is indeed a 12v coil. However, it depends on the ignitation if you need a ballast or not. He said if you have points or a Unilight that you need to have one or even 2 ballast's. He wasnt sure of Proform.

He did send me this.

 

[Big_John]

I called Holley this morning and spoke to MSD. He said that the Blaster 2 is indeed a 12v coil. However, it depends on the ignitation if you need a ballast or not. He said if you have points or a Unilight that you need to have one or even 2 ballast's. He wasnt sure of Proform.

He did send me this.

View attachment 601728

Ohm's Law

V=I x R

V=volts
I=current or amperage
R=resistance

Take the top row in that table. 24 amps x .5 ohms = 12 volts and 28 amps x .5 ohms = 14 volts.
Bottom row 2 amps x 6 ohms = 12 volts and 2.33 amps x 6 ohms = 13.98 (round up to 14) volts

 

[Scoopy G]

I can't offer any scientific information, but I can offer some anecdotal info: I have coils on my 67 Newport and 65 NYer that say, in essence, "Does not require and external ballast resistor". So, I deleted the resistors from both cars, and 4 years on I have had no problems whatsoever.

I know I'm gonna regret posting this....

 

[Big_John]

I can't offer any scientific information, but I can offer some anecdotal info: I have coils on my 67 Newport and 65 NYer that say, in essence, "Does not require and external ballast resistor". So, I deleted the resistors from both cars, and 4 years on I have had no problems whatsoever.

I know I'm gonna regret posting this....

Yep, there are ignition coils that don't use the ballast resistor. The claim is they have an internal resistor and don't need an addtional external resistor.

I've never really looked into it if there actually is another resistor contained in the coil or the primary resistance is just higher. Either way, it's basically the same as having the external resistor.

The downside with those coils is with the Chrysler ignition, it bypasses the ballast resistor on starting so there is more current (which raises voltage) and gives a "hotter" spark to help it start a little easier. You don't have that advantage with your coil.

I don't see why you would regret posting that....

 

[Scoopy G]

The cars start just fine, and both cars run like they're brand new. No electrical issues once I deleted those resistors. None. 4 years and no problems whatsoever.

Why would I regret posting that? You may recall when I posted 4 years ago how I "revived" the faded black carpet in my Newport with those big wide black Sharpie markers. I just "colored" the carpet with the markers, it worked really well, and bang that job was done and the carpet looked brand new, and still does 4 years later. So, thinking this was a pretty useful hack to post on the site, I did. BUT, leave it to the naysayers...some people can't resist telling you you're wrong about something, and I found out the fumes from those Sharpie markers were gonna asphyxiate me as I was driving down the road. Probably Stubs barked that comment out, I forget.

Seems like every time I post something, there is some contrary viewpoint, and that just gets tiresome. And that's why I preface my comment with "I know I'm gonna regret posting this...".

 

[Mike66Chryslers]

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.

This is an older thread now, but I have some interesting info on the new ECUs that have 5 pins... The 5th pin does nothing, it's a 4-pin box with a dummy 5th pin.

A friend and I were driving to a car show this summer when his ECU died. He grabbed his spare ECU, which someone had given him for free. It was one of those newer made-in-China ones with the fake metal-can transistor on the case. It had 5 pins. I said it wouldn't work because he had a 4-pin setup without the dual ballast, but he said let's try it anyhow. To my surprise, the car fired up and he's been using it ever since.