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Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Sinitro] #3061350
07/21/22 01:46 PM
07/21/22 01:46 PM
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Originally Posted by Sinitro
Originally Posted by Sniper
Originally Posted by Sinitro
The ignition system components should be matched to work the best...
Note that the task of the ballast resistor is to prevent damage by high current, as the internal coil windings are a smaller gauge wire which is more fragile......

Just my $0.02... wink


This is correct, it also limits heating of the coil.

The condenser is there to prevent points pitting, there are no points on an electronic ignition system and every mopar electronic ignition setup I ever seen, not counting EFI, uses a ballast.

Not sure why the OP is seeing 6v listings, go look at RockAuto, every coil listed for a 77 Fury that gives a voltage rating all say 12v.



Several years back..
MSD made (2) ECU boxes with the Mopar 4 pin OE connector, when installing these MSD recommended NO ballast resistor was required. In fact they actually provided a wire lead to jump and bypass the ballast resistor. In my install I took another ballast resistor, gutted it and put in a straight wire so when installed it looked OE.

Just my $0.02... wink

In 1978 I purchased an MSD5C. Here are some photos of the specs and installation instructions

IMG_1793a.JPGIMG_1791a.JPGIMG_1792a.JPGIMG_1794a.JPG

74 Challenger, bought it new. In 1978 I replaced the original 318 with a 446 and 727. Mild cam, Jardine headers, and Holley Sniper EFI.
New engine! 511" RB, Edelbrock Performer RPM heads, Eagle rotating assy, Comp hyd roller cam, Doug's 2" headers.
Re: 12 volt coil on an electronic ignition with ballast resistor [Re: randavis] #3061353
07/21/22 01:51 PM
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My 74 Challenger came with the one approved coil. I ran this setup until 1989 when I parked the car. The ballast resistor was jumpered per the instructions.
In 2016, I had the car restored and ran the same coil and MSD5C for two more years. It was still working when I took it off and installed the Holley EFI ignition box.


74 Challenger, bought it new. In 1978 I replaced the original 318 with a 446 and 727. Mild cam, Jardine headers, and Holley Sniper EFI.
New engine! 511" RB, Edelbrock Performer RPM heads, Eagle rotating assy, Comp hyd roller cam, Doug's 2" headers.
Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Sniper] #3061354
07/21/22 01:55 PM
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Meaning the ballast resistor has diddly to do with points pitting, that is the condenser's job.

Tell us why an electronic ignition system still uses a ballast if the ballast's job is to prevent points pitting.

[/quote]

Not completely true, you still have to limit the system current for the points. The ballast and coil combo did that. The condenser does absorb the voltage spike to protect the points, but system current was limited too.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: dragon slayer] #3061375
07/21/22 02:40 PM
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Originally Posted by dragon slayer
...As far as the application to electronics, as another person asked, the reason it is applicable is because mopar used the same coil. Including a ballast. So in an apple to apple comparison it explains what is going on. The points replaced by the reluctor and the electronic transistor. Rest remained the same. The ballast limited current to the electronic box and to the coil via the double ballast. Later the electronic changed and only the coil ballast was required...

OK, but it would seem the major benefit of the resistor was to limit the potential arcing arcross the points...in the meantime, in a pure electronic system you generate an impulse when the reluctor passes the magnet in the distributor pickup, and so there really is no actual direct current flow here, no need to avoid an arc across the contact points type of a situation.

So anyways, that has always been a point of confusion for me as applicable to this "do you NEED to, or NOT" to run the ballast in an electronic (non-conctact) setup.

Otherwise, yes, I do understand the overall big-picture theory here.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Cab_Burge] #3061385
07/21/22 02:50 PM
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Well, I can see this is one of those topics that will never be agreed on. But, what some of you are saying is we have been living for decades with insufficient coils and NOBODY bothered to improve on one. And, the idea that MSD doesn't put more energy in a coil that those old points is one I can't agree with.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Diplomat360] #3061404
07/21/22 03:18 PM
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Originally Posted by Diplomat360
Originally Posted by Bob Stinson
I have seen and heard many people say you do not need a ballast in a Mopar electronic system if you have a coil capable of operating at a full 12v, such as an MSD Blaster. Is that true or not?

Well, I'll tell you this: what Dragon Slayer wrote emphasizes the points-based "duty-cycle" limits, which is all great, but since I've never actually ran a points-based system I'm still not sure how this applies to a pure electronics based setups?

My thinking for a quasi-standard Mopar Chrome box configuration is as follows:
- if I have a coil that supports the full voltage and will NOT burn out early, I might as well do so
- I therefore gutted the factory ballast resitor and soldered in a straight wire
- the coil is the Accel Yellow Tower, ECU is the MP Chrome Box

RESULTS: I have been running this way for about 5 yrs now (summer cruising season to be clear), the spark is hot enough to let me run a 0.045" gap on a 10:1 motor (street), plugs stay clean, motor does not load up or break up at higher RPM. In other words, here it seems to work.

Now, to prove it out I had actually picked up a KAL Equip 'Spark Tester', model# KM2969. This thing is supposed to be able to measure Spark: Peak (Kv), Burn (Kv) and Burn Time (ms). The problem was that this was an eBay purchase and subsequently I have no manual to rely on, nor do I know for a fact that the results are correct.

Anyways...tried a few things, but results were pretty much the same regardless of whether I was running the resistor or not.

BTW - If anyone out there does actually have the manual for this thing, please, please...send it my way!!! LOL


Thanks. This is a link to the manual you need https://www.manuallib.com/file/2628282


69 road runner A12 ex-racer
71 Duster w/ a 400

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Re: 12 volt coil on an electronic ignition with ballast resistor [Re: SportF] #3061556
07/22/22 07:58 AM
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Originally Posted by SportF
Well, I can see this is one of those topics that will never be agreed on. But, what some of you are saying is we have been living for decades with insufficient coils and NOBODY bothered to improve on one. And, the idea that MSD doesn't put more energy in a coil that those old points is one I can't agree with.


I don't think I saw anyone say that. Certainly not my intention. Mopar did make some better coils for electronic ignition under mopar performance. But you still ran a ballast, the values were just different. The sought-after race one was .25ohms. There is a chart floating around on A and B body only that would match the box, ballast and coil.

But why did you need an improved system in the late 70s when motor size, horsepower were going down. These were passenger cars. If you look at the GM mod guys do, your using a GM coil, not the mopar oil filled ones.

When the super stock cars moved to the prestolite box, it was the box, a low ohm ballast, and a special coil. Now the points only interrupted a very small current to fire the transistor, and they removed the condenser in the distributor and went with the very small point contact pad with heavy spring pressure to prevent point bounce and handle the higher 6400 to 6800 RPM of the hemi in 64/65.

So full circle, if a manufacture of the box today, states no ballast needed, they also specify a coil meant to work with the system, and they control current flow inside the box. Either with an internal resistor, or circuitry. But it still is an induction system. The coil is charged with current, and that takes time to reach the necessary charge to fire the plug. As RPM goes up less and less time to charge coil. If you significantly raise current than coil charges faster and at low rpm overcharges (saturates the coil), and coil temperature rises.

MSD is a totally different system. You are not charging the coil, you are charging Capacitors in the MSD box via a step-up voltage. Basically, charging the capacitors to 500V. When triggered the capacitor discharge through the coil which now acts as a step up transformer and creates the high voltage, low current discharge to the spark plug. Now you can multi spark because you are no longer relying on the coil to charge, your stored energy is in the MSD box.

From an MSD article, ""Up to this point we have mostly covered stock ignition systems which are classified as a inductive system because they rely on the coil to do the heavy work. These ignition systems do a decent job of creating combustion within an engine. However, if high horsepower is your goal then MSD suggests you should look at a capacitive discharge (CD) ignition. “The biggest advantage of a CD ignition system is its ability to produce full-power sparks through the engine’s entire RPM range with no fear of a weak spark at the top end,”

The CD ignition draws voltage supply from the battery and steps up the voltage to 500 volts and higher, it then stores the voltage in the ignition’s capacitor. Once it receives a trigger signal it will then slam the coil with this voltage and the outcome is a current that could reach the 30,000 to 45,000-volt range. The result is more heat in the cylinder which creates improved combustion."

Take the last sentence with a grain of salt. Engineering results are that 20-25KV is sufficient to fire a FOULED plug in testing. As long as the spark is sufficient to fire the plug and ignite the proper mixture, the extra volts does not mean more horse power, just more heat on the plug, and more wear and wasted engery.

Also not they say current, but describe voltage, so even the writer is miss using terms.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Bob Stinson] #3061564
07/22/22 08:32 AM
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Bob!

Originally Posted by Bob Stinson

Thanks. This is a link to the manual you need https://www.manuallib.com/file/2628282

Thank you kindly...this is exactly what I needed to find.

In hindsight I probably should have at least tried searching for "model 2969" instead of "model# KM2969", as that KM and 2969 don't always appear together!

Well, once the new motor is up and running I'm certainly going to give this a "go"...

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: dragon slayer] #3061575
07/22/22 10:03 AM
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I'm not buying these discussions. Also, no one has correctly described the function of the capacitor. You've described side effects, but not the primary function. And, if the coil is not a transformer, then there is a different definition for coil than I have ever heard.

Check out the spark you get without a capacitor. Weak at best. Ah, but why?

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: SportF] #3061624
07/22/22 01:13 PM
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What specifically don't you agree on?

The condenser does 2 things. It helps the coil generate higher secondary voltage because it speeds up the collapse of the magnetic field in the coil by providing a path for primary current to flow to ground, since the condenser is in parallel with the points which are now open. Second, it reduces the arc across the points contact which reduces wear on the points and extends their life.

The coil is a transformer, but it operates as an inductor not a typical transformer, like a power pack. If it did the spark plug would fire as soon as the voltage got high enough. The coil (like an inductor) stores energy in the form of magnetic field. When the primary current stops flowing the field wants to collapse. But an inductor resists instant changes in current flow. The coil does step up the voltage through the winding count, but it is the collapsing magnet field that is looking for a path to discharge back to battery ground. Jumping the gap of the plug does that. Have a bad cap, or wires it could jump there and never spark at the plug.

The ballast actually is a variable resistor based on current flow and heat. At low engine speeds the ballast warms up and its resistance increases. This reduces current flow in the system which limits the arcing of the points and extends their life. At high speeds the ballast stays cooler and has a lower resistance. This allows higher current to flow but for shorter periods of time because you're firing quicker at high rpm. The ballast does limit the current at low speeds and this prevents the coil from overheating and breaking down.

It is a system and all the parts match to the need. They do have dual purpose.

That is why the box maker typically specifies the ballast resistance (if needed) and the coils that are compatible. It is not just the coil resistance which controls current flow, but the coil has an inductance value too, and that determines how fast it saturates for a given current.

It is not that points can't interrupt a higher current, but they do wear much faster and that did not meet a passenger car longevity criterion. The manufacture had to consider poor Maintenace practices. Excess wear with no points gap adjustment, and the gap widens, the dwell decreases and the ignition starts to misfire, foul plugs, and then stop working.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: dragon slayer] #3061630
07/22/22 02:07 PM
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Actually, when the points got pitted they grew closer together, not wider apart. scope
Same thing on the rubbing block, it wore and allowed the points to grow closer together scope
The condenser acts as a storage device for the coil's voltage, it is supposed to help level the voltage flow to the coil when it is getting charged up to fire.
The condenser body is not grounded to the storage material inside it, you can charge a condenser up and let it sit overnight or longer and then ground the input wire and it will discharge the condenser.
My high school auto shop instructor taught us that on the first day of school in his shop, he had charged up condenser on every desk and told us to not touch them, of course some did and got shocked by them, me to when another student tossed one to me later out in the shop whiney rant Hurt like heck, dang it rant: down:

Last edited by Cab_Burge; 07/22/22 02:08 PM.

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Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Cab_Burge] #3061638
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Originally Posted by Cab_Burge
Actually, when the points got pitted they grew closer together, not wider apart. scope
Same thing on the rubbing block, it wore and allowed the points to grow closer together scope
The condenser acts as a storage device for the coil's voltage, it is supposed to help level the voltage flow to the coil when it is getting charged up to fire.
The condenser body is not grounded to the storage material inside it, you can charge a condenser up and let it sit overnight or longer and then ground the input wire and it will discharge the condenser.
My high school auto shop instructor taught us that on the first day of school in his shop, he had charged up condenser on every desk and told us to not touch them, of course some did and got shocked by them, me to when another student tossed one to me later out in the shop whiney rant Hurt like heck, dang it rant: down:




Guess what is on both sides of the condenser when the coil is being charged? GROUND. It does NOTHING "to help level the voltage flow to the coil when it is getting charged up to fire." What it does do is take some of the current back flow from the coil's magnetic field collapse to charge itself as the points open thereby reducing the amount of current going thru the arc made when those same points open. This lessens the pitting on the points.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Sniper] #3061652
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A condensers ability to hold and discharge has a great deal to do with the points longevity. Points will pit on one side or the other depending on the condensers ability. I do not remember the exact term but to keep it simple if the condenser is under capacity it will arc on one or the other points contact and start a metal transfer. If over it will do the opposite on the other side of the points contact.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Sniper] #3061653
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Ignition condensers have a thin flat metal piece inside hook up to the wire with an insulator separating them from the case and wire, correct?
The outer case is not grounded to the storage devices so they will hold the stored charge, correct?
'If you touch the wire to the case on a charge condenser it will fire the stored charge back into the case, correct shruggy
Inductance is one of the mysteries of electrical components I never got deep into, there was no need for that in my job shruggy
Speaking of that I just remembered hearing the electrical term of Joules and mini-Joules in the classes I took on Electonics years ago
I'll see how the internet describes those terms and its application to us today luck
Bing says it is a unit use to measure energy and the amount of work it will measure according to the International Systems of Units according to Bing shruggy


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Re: 12 volt coil on an electronic ignition with ballast resistor [Re: Cab_Burge] #3061777
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Cab, you need to think about what you're saying. Does a spark plug gap grow or close (no fouling)? Does an arc welding tool increase the rod length when welding? When points arc, it wears away metal and the gap grows. But yes as the rubbing block wears the gap closes.

The condenser does go to ground. The case is grounded to the plate. Current cannot flow into an electrical device and less it can get back to the source (battery) via ground.

When points are closed the voltage at the points terminal (the moving arm) is near zero. Grounded to battery. The metal lead from the capacitor sees no potential voltage and the current takes the path of least resistance and flow through points.

As the points just start to open, the coil, acting like an inductor on the primary side, resist the change of current. The primary current has to go somewhere. It won't instantaneously go to zero. So it starts to jump the contact gap. But this generates a resistance, and the voltage rises at the terminal, and the capacitor starts charging and the current flows into the capacitor raising voltage, allowing the primary current to collapse faster, which collapses the magnetic field in the coil faster, which causes the secondary voltage to rise faster. The drop in current caused by the condenser taking a charge and the resistance of points growing as the gap increases (air poor conductor) cause the arc on the contact to collapse faster and current stop flowing across the contact arc. Less wear on points, faster collapse of magnetic field. If the condenser was not there the only path for current back to the battery would be the points. Current would flow longer to the points, and the magnetic field in primary would collapse slower. A slower collapse would mean a slower secondary voltage rise as the magnetic field collapsing needs that stored energy transformer to current to go somewhere? That somewhere is a jump across the spark plug gap when the voltage reaches 10-15KV.

The circuit is a series circuit, except the condenser which is in parallel across the points. It does connect to ground just like the bottom arm of the points through the breaker plate.

For those actually interest in the details, just do a google search on ignition types, and go deeper into the 3rd page of google past the ads and bs.

Also the Master training documents from chrysler are available on web and do a great job of basic electricity, magnetism, and ignition system, among all the other typic like combustion, mechancial, pressure etc....

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: dragon slayer] #3061797
07/23/22 09:43 AM
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I'm surprised to see this talk of "points" is still going on. Who in their right mind still uses points? If you are building a 100% bone stock ride then it's different. The ballast resistor cut's the voltage because the coil and condenser are not designed(100% duty cycle) for constant 12 volts plain and simple. As you see in the MSD list of coils some are made with heavier gauge wire and can handle full 12v where others will heat up to the point of failure(shorting out).

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: dragon slayer] #3061804
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"The condenser does 2 things. It helps the coil generate higher secondary voltage because it speeds up the collapse of the magnetic field in the coil by providing a path for primary current to flow to ground, since the condenser is in parallel with the points which are now open. Second, it reduces the arc across the points contact which reduces wear on the points and extends their life."

The first part of the first sentence I agree with. The second sentence I agree with totally. The wire going into a capacitor is NOT connected to ground in any way internally. The key to getting a good spark is the speed of the field collapse.

It would be fun to sit around and discuss this personally, not as much fun doing it here. I am sure you would agree, when Charles Kettering invented this system, there was a lot more engineering going on than most people realize. This system, among a few others, made Charles Kettering a rich and reasonably famous person.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: SportF] #3061824
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Look at a capacitor definition on the web. It is plates with a dielectric between them that can collect and retain a charge. You need a positive and a negative terminal. The case is the negative terminal. Otherwise, it could not collect a charge as current would not flow into it. Several have made this error.
Don't believe me. Take some insulated material and a nylon washer and isolate the condenser when you mount it on the breaker plate. See what happens. No return path to ground. You can't have a single lead condenser. Just like the transistor emitter on the original electronic box is the case of the transistor that shows. It attaches to the box case which is grounded. Some devices are made that way. Same as the diodes in an alternator. A single lead, but the metal diode case is the second lead. No return path. No worky up

Last edited by dragon slayer; 07/23/22 12:11 PM.
Re: 12 volt coil on an electronic ignition with ballast resistor [Re: dragon slayer] #3061832
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Yes, the case is the ground. But the wire going into the cap has No connection to the case, or ground.

Re: 12 volt coil on an electronic ignition with ballast resistor [Re: SportF] #3061842
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Man, I love a good discussion up boogie grin
What amazes me Is how two different hotrodders looking at the same information come away with two different ways of describing what they learned shruggy work


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