hot ballast resistor

[shifty]

I got the rat ('68 1600) to start today!

But the ballast resistor is getting really hot. Do these go bad?

I'm pretty sure all of the wiring is correct. Any suggestions?

[exit64]

Do you have a stock coil in the car? Or one with the correct resistance? Also, clean the terminals and look on the back side and make sure that there isn't an insect nest that could be shorting it out. Don't ask me how I know about that one Does the ignition switch get hot? Also, open the hood at night with the ignition on and the lights off and wiggle wires around and look for shorts. THey will be the cool looking flashes of light that shouldn't be there. Good luck. I know my methods are unorthodox but they usually give me the results I am after.
Mike
AKA Exit64

[Datsundude]

Hi Leigh,

I had this same issue before and fixed…my ignition coil and ballast resister would get so hot it would burn my finger if I touch.
What cause it to get hot was the distributor point, the point was incorrectly set too close….when the point set too close it would continuously feeding power to distributor.
It should be open and close, open no power going through and close power flowing through so my case was It have power flowing through at all time.

Try readjusting the point on your distributor…open it as much as it can and fire up the engine and let it run for a few minutes, feel the ignition coil and ballast resistor to see if it still hot.
If it still hot open it up some more….I had to do it a few time to get right.

Let us know if this fixed your problem.


Vinh

[spyder]

Disconnect the wires on the coil and check its ohm value. Mine are around 3 ohms. If it is much lower it will draw more current and cause the resistor to heat more than it should. I checked several resistors I have and found the average value around 3 ohms. Therefore a 3 ohm coil and resistor will give a total around 6 ohms. 12 volts into 6 ohms equals 2 amps. Since the voltage is split between the coil and resistor each ons will get 6 volts. Ohm's law says watts is volts times amps. The amps are 2 and the volts are 6 which equals 12 watts. A ballast resistor should be able to dissapate 12 watts. It might get hot but this should not be a problem. Now to further complicate, these calculations are assuming steady state as in the motor not running and points closed. When the motor is running the current is not allways flowing so the resistor should not get as hot.

Bottom line? Wrong or shorted coil.

[shifty]

Thanks guys! I will check all of that out (been down with the stomach flu for a few days).

The coil is stock, as is the resistor. Funny thing is I had the same problem with my '69 2000 before switching to a Boone dizzy. Makes me think I'm doing something wrong, but I have checked the wiring over and over. I'll look for shorts and check the points and bust out the multi-meter.

[itsa68]

I took a look my ballast resistor awhile back an found that the connections between the screws and resistor coil were corroded.
Removed the screws and spade connectors and gave everything a thorough cleaning.
Also found that the ground wire inside the dizzy was hanging on by a single strand but I couldnt initially see it because the insulation still looked intact. Replaced the dizzy ground wire.
That seemed to do the trick for me.

Ray B.

[shifty]

And the winner is:

Bad coil!

[ppeters914]

Funny thing is I had the same problem with my '69 2000 before switching to a Boone dizzy.

And the winner is: Bad coil!

Reviewing Zippy's upgrade, you also replaced the...TA-DA!.....coil.

[shifty]

Yep, the old memory ain't what it used to be! I just turned 40, now I have to take off my glasses to see things up close and can never remember where I put that wrench I just had in my hand.....

[dynaguy]

Hey Leigh, Just wait until you hit 50yrs old. I've had a terrible case of the 'Here After' disease. That's when you walk into a room, look around a bit and say to yourself "What was I 'Here After'". Pat Mahoney p.s. aging not so gracefully at 52.