Ballast Resistor Why?

-
D

Denvermike

Well-Known Member
Joined
May 21, 2010
Messages
506
Reaction score
187
Location
Denver
I have read the 1966 FSM that I have and understand the Ballast Resistor changes the amount of current and this helps extends the contact life. I went thru some GM tune up training classes in the early 70's. They didn't have anything like it. I don't think Ford did either. Any real ideas why Mopar used them? Also why not just remove them, do a little rewiring and have one less thing to worry about and or go wrong?
Mike
 
Chrysler used them on their contact and electronic ignition systems. If you're running the electronic eg. orange box you need it. You can delete it if you go to any of the new ignition systems. I always stuck with orange boxes so not sure the brands of other systems.

Terry
 
Because the way Mopars are wired is different from GM/Ford! When the ignition switch is turned to "start" the circuit bypasses the resistor, sending 12 volts to the coil for a hotter spark to get the engine started. In the "run" position, only 6 volts is sent to the coil. As "demon seed" said, many aftermarket ignitions like MSD get rid of the resistor totally.
 
I read an article at one time that said the ballast resistor was first implemented on points ignition to lower the voltage and extend the life of the points.

Every time I mention it I get told I'm wrong.

I guess I didn't read it.
 
I always thought they were to reduce point arcing with 6 volts from the ballast. I don't believe the old 6 volt systems had them or needed them. And yes Ford and GM used ballast resistors or resistor wire on their 12 volt point ignitions. tmm
 
GM used a ballast resistor similar to the mopar,, with the resistor bypass being the second small wire on the starter solenoid, at the starter...

Ford used a 1.4 ohm resistor wire (pink) in the harness to reduce voltage,, with the resistor bypass being the second small wire on the black solenoid mounted on the inner fender or similar..

The resistors knocked the voltage down to approx 9.6v.. to lengthen point life..
 
inertia said:
GM used a ballast resistor similar to the mopar,, with the resistor bypass being the second small wire on the starter solenoid, at the starter...

Ford used a 1.4 ohm resistor wire (pink) in the harness to reduce voltage,, with the resistor bypass being the second small wire on the black solenoid mounted on the inner fender or similar.

The resistors knocked the voltage down to approx 9.6v.. to lengthen point life..
Click to expand...

Yes sir!
 
Primary intent of a Ballast resistor, is, to limit the current going to the coil. Reducing the voltage, is a secondary effect.

Ballast resistors are related to the coil, not the type of ignition system (whether points or electronic).

Ballast resistors change their resistance as they heat up, they run hotter at slow engine speeds, thus limiting the current to the coil stopping the coil from overheating at low speed. As engine speed increases, so does the current as the Ballast resistor cools down, to keep the spark voltage high.

Most systems have a bypass while cranking feature, to ensure good voltage to the coil when the battery is not at it's best.

Most British cars didn't use a Ballast resister (not one you could see), as, it was already incorporated in the coil, until about 1970. About that time, they went to a resistor wire, and, 12v bypass system to improve starting in cold climates.

These early Ballasted coils are known as 12 volt coils. Ballast resistor coils are 8-9 volts rating.

Prolonging point life was the job of the condensor, not the Ballast resistor. The condenser is there to reduce the voltage spikes (arcing) that would otherwise eat the points.

Al(BWA)
 
Ballasted coils can be found on Chevys from the 50s and early 60s.It used to be printed right on the coil;"not for use with external ballast resistor" or something like that. Its a little fuzzy up there today.
 
Trying to remember if my 59 Chebby Appache 3500 had a 12v coil, or, Ballast resister.

I'm pretty sure it didn't have the 12v cranking bypass, so, I'm betting on no external BR.......


Like you say, fuzzy days ahead......:violent1:
 
inertia said:
GM used a ballast resistor similar to the mopar,, with the resistor bypass being the second small wire on the starter solenoid, at the starter...

Ford used a 1.4 ohm resistor wire (pink) in the harness to reduce voltage,, with the resistor bypass being the second small wire on the black solenoid mounted on the inner fender or similar..

The resistors knocked the voltage down to approx 9.6v.. to lengthen point life..
Click to expand...

Exactly right!
 
Denvermike said:
I have read the 1966 FSM that I have and understand the Ballast Resistor changes the amount of current and this helps extends the contact life. I went thru some GM tune up training classes in the early 70's. They didn't have anything like it. I don't think Ford did either. Any real ideas why Mopar used them? Also why not just remove them, do a little rewiring and have one less thing to worry about and or go wrong?
Mike
Click to expand...

66 model year
Plain and simple to reduce voltage to the coil / points so they don't fry the points.
 
Not so. It controls the current to the coil.

The condenser is what protects the points.
 
There is a lot of technical writing about this and a lot of talk of ballast resistance and keeping the coil cool so it doesn't fail. It is all very interesting that the engineers discovered the resistance change could benefit coil heating and prevent failure. It apparently works because coils can last for decades. I learned something tonight. tmm
 
In 65 GM Pontiac and Chev used a resistor wire instead of an actual resistor to limit the current through the points. The resistor wire was bypassed for starting only.
 
You are incorrect to say that GM did not have "anything like it" because GM most certainly did. ALL pre HEI GM products used a resistor WIRE that went to the ignition coil and reduced voltage, much the same as the ballast does for Chrysler.
 
You must log in or register to reply here.
-

Back
Top