Coil supply Voltage

[Barry_Calgary]

Hi All,
I recently realized that the ballast resistor
Was still utilized in my RR although it has
A newer style Electronic Distributor.
I understand that the ballast resistor is only
Needed on the old points style systems to
Limit the amount of current through the points,
I soldered a peace if wire to eliminate the resistor.
Question is should I be recieving 12VDC at the
Coil with the ignition on because I am only
Reading 9?
Thanks in advance for your help!

 

[Mopars & Missiles]

Mopar Performance electronic conversion distributors and original coils REQUIRE a ballast resistor in circuit for proper operation. The ballast resistor is there to protect the ignition COIL from excessive current which in turn causes excessive HEAT which in turn, KILLS coils. Yes, on the original breaker point system, the ballast resistor also helped to reduce breaker point arcing and prolong point life, but it was still protecting the coil from overheating as well.

If perhaps you are using some OTHER brand of distributor with the corresponding coil, THEN you very well may be able to eliminate the ballast resistor without damaging the coil. That information will be contained within the INSTRUCTIONS for the conversion kit.

But just eliminating a part because you HEARD this or that without fully understanding the complete circuit is just asking for more trouble later on.

The next thread you will be starting will be titled: WHY IS MY IGNITION COIL REPEATEDLY FAILING?

 

[383man]

What Mopars & Missiles said is correct. But if you jumped the ballast you should read about battery volts at the coil + with the key on eng not running. Let us know what ign system you have so we can tell you if your coil may burn out or not. Ron

 

[440+6]

I run the ballast on my MP electronic conversion but I found this article a while back and it makes me wonder if I should.

http://www.moparmusclemagazine.com/...110_ballast_resistor_guide_ballast_blast_off/

 

[bm02tj]

What would work better for life and performance is to have transformer to give you full needed amperage at the maximum voltage the coil will live at as the voltage drops with a resistor as current rises
and to set minds strait the condenser is what protects the points and is sized for the voltage

 

[Barry_Calgary]

Thanks for the responses, I have installed
A Mopar performance distributor, the installation
Instructions say ground the neg side of the coil turn on the ignition
And measure the voltage at the coil. If less than 12 volts remove the
Resistor. I initially had 5.6VDC now without the resistor I have 9 volts.
I would have thought I need 12 volts to make a 12 volt coil work effectively?

- - - Updated - - -

440+6 I also read the same article that basically
States that if you don't have a points style
Distributor you don't need a ballast resistor.

 

[A383Wing]

well, you better read it again....unless you got a coil that is internally resisted, yer gonna burn 'em up without the ballast. Makes no difference if you got points or Mopar electronic ignition. Look at all the cars and you will see on original units, all had the ballast when the cars were made

 

[383man]

I saw that Mopar Muscle article also and it is wrong from all the teaching I have had as a tech all my life. I agree it will let the coil put out higher voltage if needed but if anyone tries it see how hot your coil gets after awhile. The Mopar electronic ign is still made to use the ballast. After some years they eliminated the 5 ohm side of the ballast that went to the ECU as it was just an auxilary circuit to turn on the ECU as thats why they had the dual ballast for years as the coil side was about .75 ohms and the auxilary side was 5 ohms. It will run if you bypass the ballast but you may burn the coil up after a bit. Many people dont know that Ford and GM cars up into the 70's also had resistance in the primary ign circuit as they used a resistance wire in the wire harness to drop the voltage to the coil also and Ford still used it on the first electronic ign they came out with in the early 70's. Thats why both Ford and GM have a resister bypass circuit on their starter solenoids to put a full 12 volts to the coil when cranking the eng. Mopar did the same as we bypassed the ballast when cranking by the ign switch which is "ign 2" terminal. I can tell you one thing and that is we took the Mopar ign off my sons Dart and put MSD on it with no ballast as you dont need it with MSD and his car started the same as it did with the Mopar ign and it ran the same et in the 1/4 as it was no faster with the MSD.
If you run it without the ballast I would carry and extra coil and Mopar ECU in the car with you. Are you sure you jumped across the ballast right with good connection. Because with the key on eng not running you should have battery volts (12 volts) at the blue ign wire at the ballast and if you jumped it right you should also have 12 volts at the other side of the ballast and at your coil + side if the wireing is good. But I would use the ballast as I would think your car has run fine using the ballast ? Now you do know they make different ohm ballast from about .25 to about 1.75 is what I have seen over the years. Ron

 

[Mopars & Missiles]

......and to set minds strait the condenser is what protects the points....

Yes, I will give you that, the condenser does PLAY A PART in prolonging breaker point life. The breaker points are the ON/OFF switch for the primary ignition circuit. When the points are closed (switch is on), current begins flowing through the ballast resistor (which limits current to the coil) into the primary winding of the coil saturating the winding and flowing on through the points (resulting in arcing of the points as they make contact) and then flowing to GROUND.

When the points are opened (switch is off) current is interrupted (resulting in more arcing of the points as they break contact). This results in the collapse of the magnetic field in the primary winding of the coil which induces a voltage PULSE into the secondary (HIGH Voltage) side of the coil. This high voltage in the secondary circuit of the coil (about 30-40K volts) is then discharged through the coil Hi Voltage wire to the distributor cap and then routed to the appropriate spark plug by the rotor which aligns with one of the Hi Voltage towers on the distributor cap. The Hi voltage jumps the air gap of the spark plug to ground creating the "spark" that ignites the air/fuel mixture in the cylinder.

So, each time the breaker points OPEN or CLOSE an electrical arc is created which, over time destroys the breaker points. By limiting the circuit current (ballast resistor in series) point life is extended as well as coil life by reducing the heat build-up in the coil. The condenser does NOT pass DC current, it blocks it. So, the condenser is placed in PARALLEL with the breaker points. The condenser then acts as a "shock absorber" to the points as they OPEN and CLOSE which in turn ALSO helps to extend the breaker point life.

Below info is taken from my 1969 Factory Service Manual (FSM).



So you say, what is the difference between a "breaker point" system and the Mopar Performance Electronic conversion system? Not as much as you would think. The "Orange Box" that so many have on their cars is simply a "Transistor Switch" that has replaced the "breaker points". The "Reluctor and Magnetic Pickup Coil" inside the conversion distributor is now the "Trigger" to turn the transistor switch ON and OFF in the ECM or Orange Box. The big advantages of this system are that the Transistor switch does NOT have any arcing or burning of the contacts, so life is extended tremendously. Also the transistor can supply much more consistent, accurate pulses at high engine speeds because there is NO contact bounce as there was with "breaker points". The transistor switch is also chosen specifically to match and handle the expected amount of current in the circuit and is mounted on a "Heat Sink" to dissipate the heat built up due to the current flow in the primary ignition circuit. When you upgrade from Orange to a "Chrome Box" or the race "Gold Box", you are getting an even better "Transistor Switch" which is capable of faster switching times (think higher engine RPM's) and is also capable of withstanding even higher amounts of primary circuit current, and heat dissipation.

 

[383man]

Very well said Mopars & Missiles. I will also say I remember some years back a guy who burnt out a few of the chrome MP ECU boxes as he was not using the ballast. He also wanted more coil output and thought that would work but he put a ballast back on the car. Another thing to remember is the coil on an average electronic ign like the MP that most of use use will usually put out 25k or more but it only puts out near that if it needs to as the coil will fire and once the spark jumps the rotor and plug gaps it wont put out any more. At idle most coils only put out about 5 to 7k as thats all it needs to in overcoming the resistance in the secondary circuit at idle but at wide open throttle it might want 15k or more since the eng is taking in much more air and fuel and running comp is up some so it will need more voltage to overcome the resistance and gaps. Your ign should put out more then enough for your car. Myself I have been using the orange MP ECU and an older Acell coil since 2006 with the stock ballast and it never misses a beat pushing my 3700 lb 63 into the 10's. But like I was saying if you decide to run without the ballast like Mopar Muscle said which is wrong make sure you carry a spare coil and ECU. Ron

 

[sleepar]

I have a msd coil and it came with a ballast.... for the above reasons. I prefer points but the ballast UN hooked will do more harm to the coil than the points will ever see
How many sets of points can be had for the price of a ecu and can you adjust the dwel on an ecu.... there is a lot of performance in a set of points the boxes don't allow...... go to a jeweler and have the contacts platinum plated and they out last the car for around $80