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Ballast Resistor

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capitalcitycars

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My engine will run fine for about 10mile. Then, the engine will cut in and out. Once I stop and let Murphy sit, the car is fine. A club member told me it sounds like the ballast resistor is not connected. My car didnt come with one. Can someone tell me what it is? Is it needed, I have a dual point dist? And how is it wired? I like a second opinion. You guys have been better with these questions than my club is. Thx!
 
Bad condenser in distributor caused one of my B's to do the same thing.
 
They can be bad right out of the box!
 
On the later Midgets, the ballast resistor is built into the harness. If you have a connector with two white and green wires connected to the (+) post of your coil, you should be good to go. One of the white and green wires goes to the ingnition switch and the other goes to the ballast resistor.
 
It might be the coil. They get hot after a while and open up inside sometimes and then cool and work again. Also, clean the distributor cap with laquer thinner or something inside real good and also look for any moisture, etc. in there. I worked on a mini once that had anit freeze or something absorbed into the distributor cap and when it heated up this would condense inside and make it cut out.
 
yea, coil sounds reasonable, if it is a points dizzy, condensor is another good bet.

You're looking for something heat sensitive. Cap, rotor, wires, plugs generally aren't heat sensitive and can probably be ruled out. Coils, resistors, capacitors (like the condensor), and ignition modules on the other hand are all temperature sensitive....
 
Yes, and what causes coils to get hot people? Anyone... Anyone.... Bueller...

Survey says....

NO BALLAST RESISTOR!!!

DING DING DING DING DING

We have a winner!!!

JACK
 
[ QUOTE ]
What is the purpose of the BallastResistor?

[/ QUOTE ]

When you start your car, you get 12 volts directly to your ignition coil (during cranking). This give a good spark but the full 12 volts may overheat your coil in time.
When you release the key (key still "on" but not cranking) the electrical supply for the coil goes through a "ballast resistor", which cuts down on the current (so the coil doesn't get so hot). Spark is sufficient for running in this mode.
Some coils (like the Luca Sportcoil) have a ballast resistor built in while other cars have a "ballast wire" or seperate resisitor.
I'd suggest you check the schematic in your shop manual, since some of these cars can vary from year to year.
To keep things simple in my racer, I wired the ballast resisitor through the coil all the time (even when starting). It works fine for me, but maybe not for street cars that sit outside in the cold.

You sure you don't have a clogged fuel filter, weak fuel pump or clogged fuel tank vent?
 
Hey Aero,

Thanks for providing the explanation. I was going to give the explanation (because I think most people ignore this problem mostly from a lack of understanding. I know I did!! /ubbthreads/images/graemlins/wink.gif) but I didn't have the time. I think you did a better job of explaining it than I would have anyways /ubbthreads/images/graemlins/grin.gif

I will add that the most common "conditions/symptoms" of a ballast resistor issue are:
white powdery burnt points
burning condensors out rapidly
overly hot coil
cutting out after 10-15 minutes (time for everything to heat up)

JACK
 
Hello all,

just to expand on Aeronca65t, when starting the car the battery voltage drops due to the load from the starter motor, maybe 8 to 10 volts which would give a weak spark with a standard 12 volt coil. So Triumph fitted an 8 volt (approx) coil and linked that to an auxiliary contact on the starter solenoid. So on starting the coil is getting its full voltage. Once the engine is running the system voltage goes up to 12V + (Usually 13 to 14 volts) so the 8 volt coil would overheat due to too high a current as it is fed at too high a voltage. So a ballast resistor is fitted in series with the feed from the ignition switch to drop the coil voltage back down. It is actually a very simple idea but harder to fully explain in a couple of words.

Alec
 
Brian, I don't know when the ballast resistor was introduced, as I don't have any diagrams for the rubber bumper cars. One quick test to see if you need it is to use your Ohmmeter. Disconnect the wires from the coil and meter across the two small terminals. If the resistance is 1.5~1.9 ohms, you need a resistor. If it's in the neighborhood of 3.0~3.4 ohms, the coil is internally ballasted, and doesn't require a resistor.
Jeff
 
Coil just blew up. Should I give up since it appears i'm over my head and pay a pro? What wires should be connected to the coil on the pos and neg sides? I have a Mallory Dual Point. What wire should hook to the condensor? Jeff, If I treated you to pizza , beer and gas money, could I bribe you to come down? Is Lucas still in business and where should I send my hate mail to? Thanks to all!
 
might be mistaken, but I'm pretty sure my balast resistor is mounted adjacent to the coil, just to the front of it to be precise....
 
Brian, just send me your address, and let me know when. I'm about 15 miles east of I-96, and pick it up between Howell and Fowlerville. Gas money not required, but Labatts Blue is nice.
I'm not much of a rubber bumper guy, but the negative post of the coil goes to the distributor. I can bring both a ballasted, and non ballasted coil with me. (with the appropriate resistor.) I'm about an hour or hour and a half away.
Jeff
 
Brian, I'll see you tomorrow afternoon. I'll bring a couple of coils, a resistor, and probably a good stock distributor with me, as well as my meter. More than likely, I'll be driving the Volvo wagon.
Jeff
 
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