Hi, i talked to a fellow Mopar guy, he has a 1971 dart 340. he is running his Mopar electronic ignition with out a ballast. is it safe to not use any ballast with his Mopar ignition system and if he neededs one what ballast should he use?
Ballast
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replicaracer43
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The ballast is to reduce voltage to the coil, you can buy coils that do not require a ballast from any napa store. But running no ballast with a coil that requires one is asking for a overheated coil and trouble......
67Dart273
Well-Known Member
I would "get back" to a more street traditional setup. You can create a situation where the coil runs hot and fails, and you can have a situation where the ECU is switching too much current and fails
Additionally, I disagree with the idea of running a coil designed for no ballast. The reason is that these were designed originally so that during start, when battery voltage is lower, the ballast is bypassed to provide a hotter starting spark.
Additionally, I disagree with the idea of running a coil designed for no ballast. The reason is that these were designed originally so that during start, when battery voltage is lower, the ballast is bypassed to provide a hotter starting spark.
replicaracer43
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So........running a coil DESIGNED for constant 12V, you don't recommend? That seems strange. And to clarify, I wasn't suggesting that it SHOULD be done that way, just that it "can" be
You are a smart guy, no question, BUT if I am using a coil not needing a ballast, then the coil will have the full voltage avalible at all times, even when cold. And of course an ignition system not needing reduced voltage, like I am using, needs to be used as well. No ballast works fine in my setup.
nm9stheham
Well-Known Member
It is not so much the voltage at the coil for cold starting but the current through the coil; spark energy from a coil is proportional to the square of the current, so more current is better when cold. So, a ballasted coil with the ballast bypassed for starting will give you more coil current and thus more starting spark energy.
(HEI is a very different situation so this discussion is only for a 'standard' ignition system, like the Mopar electronic or points.)
For the OP and his friend, the 'no ballast' is OK if the coil is a 3 ohm coil; it just won't have the cold start feature mentioned above. If a standard 1.5 ohm coil, then a correct ballast is needed. The MSD 0.8 ohm ballast is a pretty good choice; I'd prefer the the Mopar 2095501.
BTW, for racing, when the use is not continuous, it is common to use a very low ballast resistances to get the coil current up, especially at higher RPM's when dwell time is short. But these are not meant for street use, and will overheat the coil after some time, like 20-30 minutes. Some folks think that if it is good for racing, it must be good for everything...LOL
(HEI is a very different situation so this discussion is only for a 'standard' ignition system, like the Mopar electronic or points.)
For the OP and his friend, the 'no ballast' is OK if the coil is a 3 ohm coil; it just won't have the cold start feature mentioned above. If a standard 1.5 ohm coil, then a correct ballast is needed. The MSD 0.8 ohm ballast is a pretty good choice; I'd prefer the the Mopar 2095501.
BTW, for racing, when the use is not continuous, it is common to use a very low ballast resistances to get the coil current up, especially at higher RPM's when dwell time is short. But these are not meant for street use, and will overheat the coil after some time, like 20-30 minutes. Some folks think that if it is good for racing, it must be good for everything...LOL
67Dart273
Well-Known Member
That isn't the thing. When the car is cranking, battery voltage is low. So coil voltage (and current) is reduced. Part of the reason the system was designed as it was, originally, is so you have higher voltage to the coil during cranking THAT YOU WOULD HAVE if there was no ballast there to bypass.
I'm sure using a no ballast setup works fine "most of the time." But, "on that day," when it's -20F, the oil is molasses, and the battery is down from the cold, you want all you can get. Bear in mind, "originally" these girls were not meant to be "fair weather friends."
This scenereo also holds true when you discover, upon returning to the car, that you left the radio or dome light on, and once again, to get the thing to fire, you need "all you can get."
I agree with 71 dart and the ballast "limits" current draw because the voltage drops when the starter pulls heavy current when starting. The ballast resister actually drops voltage across it and helps keep the voltage up when the ignition coli field collapses and produces the spark-producing a little hotter spark. The ohm value is .5 ohm on cranking and switches to approximately .5 ohms when the ignition switch is released and the engine runs and the alternator builds voltage to around 13 volts.
ir3333
Well-Known Member
yes... by- passed during start up because of the the voltage drop.(9 or 10 volts)
..originally the ballast was used to reduce voltage on the early points style distributors.
this is a grey area with many theories.
if you have electronic ignition, i think you can operate without a ballast...you can run without an air cleaner too,but why would you?
..originally the ballast was used to reduce voltage on the early points style distributors.
this is a grey area with many theories.
if you have electronic ignition, i think you can operate without a ballast...you can run without an air cleaner too,but why would you?
67Dart273
Well-Known Member
Actually from my point of view the solution is to use an HEI module
This operates without a ballast and even can use the factory coil (I do) but you can get more energy out with a better coil.
There is even members here who have gutted old Mopar boxes and mounted the HEI inside the Mopar box.
This operates without a ballast and even can use the factory coil (I do) but you can get more energy out with a better coil.
There is even members here who have gutted old Mopar boxes and mounted the HEI inside the Mopar box.
roccodart440
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The "original" intent for ballast resistors was to cut the voltage to the points, thus making them last longer. The coil will also get hotter without one.
at you know who. 
at you know who.
nm9stheham
Well-Known Member
nm9stheham
Well-Known Member
If that were the case, then a regular resistor would be used, not a ballast type that changes resistance with temperature. 'Ballast' has a specific meaning and function in electronics; it is a basic form of current regulator. The 'resistance' (pardon the pun) to using actual electronics knowledge in this matter is perplexing ..... ??
67Dart273
Well-Known Member
X2, From the dictionary:
: a heavy substance placed in such a way as to improve stability and control (as of the draft of a ship or the buoyancy of a balloon or submarine)
2
: something that gives stability (as in character or conduct)
3
: gravel or broken stone laid in a railroad bed or used in making concrete
4
: a device used to provide the starting voltage or to stabilize the current in a circuit (as of a fluorescent lamp)
These ballast systems were and are antiquated! We dont need them any more with technology available. They DID serve a function on old fashioned ign. systems. IF you are keeping old system on your Vehicle, then you still need a ballast.
The original one wire ballast when cold allowed full current for cold starts, when warming up it starts to "resist" the voltage thus dropping it.
In an attempt to keep a numbers car looking stock under the hood. I solder a 12 ga wire at the rear of the 2 post ballast to provide constant 12 volts. Then I use a pertonix Electronic ign system inside the stock distributor, also to keep stock looking appearance. There are two wires exiting the distributor, but I use a shrink wrap to hide the 2, and make it look more like 1. Here is a pic, although not a great one.
Nice!
Pete in NH
Well-Known Member
I'm with 67Dart273, Not using a ballast resistor will likely cause an early coil and /or ECU failure and you loose the cold temperature start boost when the battery voltage is really down.
The correct value of ballast resistor for the Chrysler ECU systems is 1.2 ohms. The GM HEI type systems don't use a separate ballast resistor but do have an electronic circuit mechanism to limit the final ramp up current value to the coil. For those who are electronically inclined look up the Motorola MC3334 data sheet on line for an explanation of this circuit. The GM HEI system was based on the MC3334.
In any of these systems it's a fairly safe bet to assume they were designed by competent engineers and tested extensively before being put into production on millions of vehicles. I would tread very lightly on second guessing what was done on these systems and making changes.
The correct value of ballast resistor for the Chrysler ECU systems is 1.2 ohms. The GM HEI type systems don't use a separate ballast resistor but do have an electronic circuit mechanism to limit the final ramp up current value to the coil. For those who are electronically inclined look up the Motorola MC3334 data sheet on line for an explanation of this circuit. The GM HEI system was based on the MC3334.
In any of these systems it's a fairly safe bet to assume they were designed by competent engineers and tested extensively before being put into production on millions of vehicles. I would tread very lightly on second guessing what was done on these systems and making changes.
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