Correct ballast resistor

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Riff Raff

Riff Raff

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I'm going to be running the Mopar electronic ignition with an Accel super coil. I've done a bit research and the answers are all over the place as far as which ballast resistor to use. Anybody with real world experience or just the right answer would be cool. Thanks, Jeff
 
Is this on a car with original electronic ignition?

The single ballast is for the coil, nothing to do with ignition.
The dual ballast is only needed with OEM 5 pin ignition modules, one side ignition, the other coil.

So the question to does the Accel super coil need a ballast or what one? I don't know.


Alan
 
I'm adding a reproduction ecu engine harness to my 71 Demon. I'll be using the super coil. So yes the question would be which is the proper resistor to use with the super coil? Thanks,Jeff
 
When you start using aftermarket coils, then you have completely changed the engineering. There is no guarantee that some other coil will work. Only way I know is "what has worked" for others and "what has not" caused coil/ box failures. There are several possible issues........

1....The ECU may not be able to handle additional coil current
2.....The box may not have low enough resistance to cause the coil to saturate
3.....A given resistor/ coil combination may cause coil or box failure or not allow enough current to generate even as powerful spark as a stock coil

There are some coil combos over the years---the big old rectangular Mallory was one---that used your stock resistor AND the supplied Mallory resistor. So they actually drew LESS current than stock
 
Well back in the day, DC had the system worked out.
This is from the Speed Secrets (Carrol Shelby cover) version of the engine book.
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P4120534 was the Chrome Box version sold in the later 80s.
Notice it could be used with a 1/4 Ohm resistor and Accel's chrome coil, but only for short periods of time (drag racing).
Same box with a production coil in theory would survive general use with a 0.5 or 0.7 Ohm resistor.
With the Accel Super coil they show any resistor between .5 and .8 Ohms will work up for applications up to 6000 rpm.
I was using that combination for a while. Then on a moderately long trip the coil began to seep oil. That was enough for me. Was it the coil? Looking back, I'd say maybe, but maybe not. Didn't know enough then to do a more thorough investigation.
 
Can’t advise on which resistor to use but I have tested a half dozen or more from local auto parts stores. None of them tested to specs listed in manual.
If you are getting one from them take your ohm meter with you.
Yote
 
The specs are hot actually they will never test proper out of the box. FSM has the testing temp usually 80 or so. Testng combos on different ECU's Resistance should be matched to have the optimum output and cooler ecu operating temperatures.
hence where does the coil get its ground from? The ecu of course one reason guys running .25 ohm resistors on chrome boxes burn them up on the street and if they run say .8 ohm they run forever but will never hit 10K rpm like they should it is a trade off really. Go with the manufacturers recommendation on the aftermarket coils.
 
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The key is to compare the resistance specs of your new coil with the oem mopar coil. If they are the same, you are ok. If your new coil is a little higher, you are still probably ok.

If your new coil is lower resistance, then you will need a larger value ballast to keep the current through the ecu the same.

Mixing ignition components is not the best idea unless you have some verification that they will work together.
 
The only thing 'super' about the Accel super coil was the price you paid for something that was nothing more than a dressed-up canister coil. It had a high turns ratio to throw a nice, long [ impressive! ] spark, but that reduced the spark current, the heat in the current being what actually ignites the mixture.
A production coil with an easy to get bal res is the best choice.
 
Lots of confusion about this topic, I have had coils leaking and overheating. I put an finned aluminum heat sink strapped to the coil, so far
OK.
 
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66jim said:
Lots of confusion about this topic, I have had coils leaking and overheating. I put an finned aluminum heat sink strapped to the coil, so far
OK.
Click to expand...
Yes there is. I have been testing different ECU and Ballast combinations If I ever get it in a spreadsheet I will post it. But in a nutshell the lower the ballast/coil ohms the higher the amp draw the higher the coil/ballast ohms the lower the amp draw and also lower heat in the components. Aftermarket you really have to match the coil/ballast to the ecu used. for ideal conditions.
 
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halifaxhops said:
View attachment 1715920166
Yes there is. I have been testing different ECU and Ballast combinations If I ever get it in a spreadsheet I will post it. But in a nutshell the lower the ballast/coil ohms the higher the amp draw the higher the coil/ballast ohms the lower the amp draw and also lower heat in the components. Aftermarket you really have to match the coil/ballast to the ecu used. for ideal conditions.
Click to expand...

That is really clever. Do you have the plug wires connected to a distributor not in the picture?
 
Yes to a cap that I can see the phasing on in a distributor on the sun tester. I can also physically see when the ecu starts to break up. I do it in the dark usually the wife thinks I am Hoppy Frankenstein!:lol:
 
Changing parts around on an ignition system is kind of like taking vitamins. Everybody “knows” they are good for you, but there is really not a lot of objective evidence. Most of the time people say they “feel better”. What does that mean? Everyone “knows” their car will run better with that cool new aftermarket coil….
 
The Accel Super Coil has a primary resistance of .7 Ohms
Similar to the MSD Blaster 2 coil

Factory Chrysler coil has a primary resistance of around 1.6 Ohms

Chrysler used the same ignition coil running there points distributors of the 60s/70s and a single ballast resistor with an .5 Ohm rating and that same part #ignition coil was used thru the mid 70s running the electronic ignition / ECU and a dual ballast resistor with an .5 Ohm rating on the coil side

Chrysler changed the Ohm rating of the dual ballast resistor to the coil side at 1.2 Ohms around mid 70s also
 
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Thanks for all the detailed advice.

I am in the process of changing over the '89 318 TBI system over to a simple one wire 1969 Replacement Points Distributor, 2 pole ballast resistor, and matching coil, all for the '69 era ignition.

Now I have a perfectly good 12 volt tower coil with the '89 TBI system, but knowing it will not be proper for the Point Ignition, decided on the '69 era ignition parts to all work together.

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☆☆☆☆☆
 
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