Correct Ballast resistor

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Princess Valiant

Princess Valiant

A.K.A. Rainy Day Auto
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So I am shopping around for an electronic ignition upgrade kit for my 71 scamp and I am noticing that some kits on the market have the bracket style ballast resistor and some have the thick style one that takes a longer bolt.

Which is more correct and which one should I get ??

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The top one visually looks correct for a factory points system circa 1967.
But since you are changing ignition systems, the functional requirement is for the resistance to match the coil and ECU. You'll have to get that from the coil and ECU manufacturer. Been some recent discussion about this, shouldn't be too hard to find the info for which ever ones you're looking at. If its an older MP system, there's a page in the Ignition Bulletin for the different Direct Connection boxes etc.

Ballast resistors for Points: Chrysler master tech bulletins
Ignition System Analysis 1969, see pages 4-5
Ballast resistors for the era electronic ignitions
from 1972 MTSC Ignition Service (Session 292)

Later Chrysler ECUs use single ballasts.
Early Chrysler ECUs used dual resistor with one dedicated to controlling ECU current as explained on this page
1973 Chrysler Electronic Ignition Diagnosis and Repair (Session 312)
 
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Unless your going for period correct I would recommend the electronic dizzy with a HEI setup and ditch the ballast resistor altogether. There is a big performance difference.
 
fklskv said:
Unless your going for period correct I would recommend the electronic dizzy with a HEI setup and ditch the ballast resistor altogether. There is a big performance difference.
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hadn't thought of that. Its not a correct car by any means but it is a very mild street car. The engine is a tired, original, low compression 340.
 
Rainy Day Auto said:
There are different resistors in each kit ???

For Mopar... Small Block 273 318 340 360 Electronic Ignition Distributor Kit | eBay

MOPAR 318 340 360 HiRev Electronic Ignition Kit Resto OEM Plymouth Dodge Chrys | eBay
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Looks that way. They might both have the same resistance reading.
Visually the distributors look the same but have different ECUs.
For a 340, I'd say the odds are better that Rick's is going to be a better match. Internally, the curve in his distributor has been set up like the old MP or 440 HiPo.
Getting the right timing curve is more important than any other characteristic. Properly curved dual point will beat an improperly curved anything else. No amount of spark energy is going to change that. A lot of sharp racers found that out in the 70s.

edit: added link to 440 timing curve
 
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Rainy Day Auto said:
So I am shopping around for an electronic ignition upgrade kit for my 71 scamp and I am noticing that some kits on the market have the bracket style ballast resistor and some have the thick style one that takes a longer bolt.

Which is more correct and which one should I get ??

View attachment 1715157640

View attachment 1715157641
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it doesn't matter what style the ballast is, all that matters is the Ohm size. I was told years ago by a Mopar mechanic for Mopar electronic ignition systems using a stock coil you should use a ballast that has 1.2 - 1.4 ohms resistance. I've allows use one in that range and have never had a problem in 30+ years with my Mopars electronic ignition systems. Here is a list of different ballast resistors I've collected over the years incase I needed one.
NAPA Echlin ICR11 (1.35 Ohms), NAPA Echlin ICR23 (1.2 Ohms), NAPA Echlin ICR34 (1.4 Ohms), Standard RU-4 (1.35 Ohms), Standard RU-23 (1.2 Ohms), Standard RU-37 (1.4 Ohms).

I always keep a spare in the glovebox so I will never be stranded on the side of the road. Even thought I only had 2 go south in all my time I've owned my Mopars. They are an electronic piece of equipment and you never know when it will stop working and I've help a few other Mopar owners over the years (that needed a ballast) with problems with their car not starting. Just my two cents worth.
 
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Which is more correct and which one should I get ??

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View attachment 1715157641[/QUOTE]

How about NONE of the above, upgrade to an Ignition System that doesn't run on 5-6V through a ballast resistor and ignition from the 1960's, join us here in this century.

The HRR688 will upgrade it and you'll never have carry a spare ignition part again.

The Only Ignition components with a 5 YEAR WARRANTY, Distributors and ECU's
 
I know this is dragging up an old thread, but I wish people would simply answer the question that asked, if they know the answer, and if they don't know, don't insert opinions unless prompted.

To refresh...the question that was posted was, in essence, what is the difference in these two ballast resistors? One has ana attached bracket, the other has no bracket and requires a longer bolt. I have the same question. I have a new to me 1972 Valiant that has the thick style resistor installed with what is clearly the wrong bolt...which isn't tight either. I also have a 1971 Scamp that has the bracket-style resistor with what looks to be a shorter, very original bolt.

Allow me to provide a quick demonstration regarding how to provide useful answers to forum questions instead of lecturing people on what you think is right or just talking to hear your head roar. Once again I had to answer my own question because of all the nonsense.

I dug through my on-the-road toolbox that I carry spares in because I recalled seeing a ballast in there. The one in there was another thick molded type, but this on had a part number...5206436, which is a very late Mopar number. With about 2 minutes of searching on the net and a trip outside to my '83 D150 to confirm, here is the actual answer to the question that was posted by the OP-

The thick molded type ballast is used on later trucks and vans, probably from about '81 on up. Those use a single ballast even though they have electronic ignition. There is one mounted right on the firewall of my truck, with the same part number.

The CARS use the single ballast with the metal bracket attached and the short bolt.

Question answered.
 
TylerW said:
I know this is dragging up an old thread, but I wish people would simply answer the question that asked, if they know the answer, and if they don't know, don't insert opinions unless prompted.

To refresh...the question that was posted was, in essence, what is the difference in these two ballast resistors? One has ana attached bracket, the other has no bracket and requires a longer bolt. I have the same question. I have a new to me 1972 Valiant that has the thick style resistor installed with what is clearly the wrong bolt...which isn't tight either. I also have a 1971 Scamp that has the bracket-style resistor with what looks to be a shorter, very original bolt.

Allow me to provide a quick demonstration regarding how to provide useful answers to forum questions instead of lecturing people on what you think is right or just talking to hear your head roar. Once again I had to answer my own question because of all the nonsense.

I dug through my on-the-road toolbox that I carry spares in because I recalled seeing a ballast in there. The one in there was another thick molded type, but this on had a part number...5206436, which is a very late Mopar number. With about 2 minutes of searching on the net and a trip outside to my '83 D150 to confirm, here is the actual answer to the question that was posted by the OP-

The thick molded type ballast is used on later trucks and vans, probably from about '81 on up. Those use a single ballast even though they have electronic ignition. There is one mounted right on the firewall of my truck, with the same part number.

The CARS use the single ballast with the metal bracket attached and the short bolt.

Question answered.
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Thanks for the correct answer, but in doing so, you also just had to chastise others as well as hear your own self "roar". Welcome to the club.
 
The shape/mounting of the BR being different means the external design was changed &/or different manufacturer. The single BR should be 0.5 ohm, & it is very hard to accurately measure with a standard DVM.
I have a special low-ohms meter that is made for low resistance readings.
 
Uhh......

d1970 said:
it doesn't matter what style the ballast is, all that matters is the Ohm size. I was told years ago by a Mopar mechanic for Mopar electronic ignition systems using a stock coil you should use a ballast that has 1.2 - 1.4 ohms resistance.
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From Halifax Hops...

ECM ch 2.png
 
Yes. Thank you for investigating and finding an application for the 5206436 ballast resistors.
RustyRatRod said:
Thanks for the correct answer, but in doing so, you also just had to chastise others as well as hear your own self "roar". Welcome to the club.
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Well it can be annoying when the answers go way off track but that is the nature of public discussions.
TylerW said:
To refresh...the question that was posted was, in essence, what is the difference in these two ballast resistors?
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Actually, No. The initial question was was which is "correct" for an upgrade kit.
Princess Valiant said:
So I am shopping around for an electronic ignition upgrade kit for my 71 scamp and I am noticing that some kits on the market have the bracket style ballast resistor and some have the thick style one that takes a longer bolt.

Which is more correct and which one should I get ??
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While you can interpret that as which one will fit, correct can also be interpreted as which one will function correctly with the kit.
It looks like I tried to answer both. Since we did not know the kits being looked at, a definative answer could not be provided.
In general, Chrysler ECU systems from 1971 through the end of the A-body era, along with Chrysler's aftermarket and MP kits used a 1/2 ohm ballast resistor in the coil circuit.
So the next question is whether the 5206436 resistor measures 0.5 ohms or 1.2 ohms cold?
Because many of the current aftermarket resistors that are single piece molded ceramic measure 1.2 ohms and are not a good match for a factory or P-part ECU and coil.
 
Mattax said:
Well it can be annoying when the answers go way off track but that is the nature of public discussions.
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I cannot disagree, however, a lot of times some of those ramblings can contain some good information.
 
So the next question is whether the 5206436 resistor measures 0.5 ohms or 1.2 ohms cold?

I wrote down 1.0 - 1.2 OHMs many moons ago
Definitely not 0.5

If individuals insist on running the single ballast resistor for upgraded electronic ignition systems on factory points type cars because of there wiring harness , why not just buy the 0.5 OHM Single Ballast Resistor from Hops and BEE done with it - Problem solved


It’s not period correct anyways because the factory used a 0.5 OHM Dual Ballast Resistor through the early to mid 70s on Chrysler Electronic

If you want a period correct Mopar Dual Ballast Resistor with the coil side of 0.5 OHM
Look for this , pretty simple as it’s clearly marked and has the OPEN ceramic back

However the same Mopar part number was used on the later ignition systems of the 70s 80s , and also was clearly marked 1.2 OHM and had the ENCLOSED ceramic back

You will not find a jobber or aftermarket Dual Ballast Resistor with a 0.5 OHM Coil Side



Like you said either way Single or Dual Ballast

0.5 OHM is the way to go

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This is the ballast resistor I got from a NAPA store. The application? 1970 Charger with a 318.

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Fifteen bucks. Cold, it tests at .7 ohms.

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I'm told that once it warms up, that number should read .5 ohms. I haven't tested it hot though.
 
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Kern Dog said:
This is the ballast resistor I got from a NAPA store. The application? 1970 Charger with a 318.

View attachment 1716291450

Fifteen bucks. Cold, it tests at .7 ohms.

View attachment 1716291451

I'm told that once it warms up, that number should read .5 ohms. I haven't tested it hot though.
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1970 Charger would be for points. There might be .1 ohms in meter leads. Its difficult to get super precise with a standard meter at these low resistances. Looks like all of the 70 engines have the same spec.
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Like you posted, the compensating resistor was about the same for the ECU equiped engines. see MTSC 1972 Browse MTSC by Model Year – 1972 – MyMopar
 
You CANNOT accurately measure very low resistances with a std DVM. They are inaccurate. Chrys made sub-one ohm BRs 0.25, 0.5 ohm & 0.7 ohm.

You need a special low-ohm meter [ below ] which has a zeroing function & reads to 3 decimal places.

Alternatively, use an ign system such as HEI which does not require a BR, gives more spark energy, is simpler to hook up & allows for 0.060" plug gaps.

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