Ballast Resistor gets hot suddenly

[James B.]

Put a 1965 Coupe 327/300 HP manual transmission on the lift today to place the two green brake line brackets on the rear crossmember today. Capped off the rear differental with gear oil and dropped the car down, started it up to move it and took notice to the smell of burning under the hood. Further investigation, I found the ballast resistor bracket very hot, but found no wires hot or burned anywhere from the ignition switch to the ballast resistor, to the coil, its connections, and wires to the starter. I placed a spare coil and ballast resistor, started the car and in a few minutes the same result.

Over the winter I had the distributor rebuilt and have the Breakerless SE electronic ignition installed. The starter was rebuilt along with the solenoid. All original components. Plug wires are the Lectric Limited dated wires. I checked wiring for breaks as I have all the Ignition Shielding in place, all is good. Ohm meter checks out good with the coils and ballast resister.

I am thinking grounding may be the reason, I did install those brackets and attach the rear brake lines to them? Any help is appreciated.


Jim

[Michael W.]

Re: Ballast Resistor gets hot suddenly

It's supposed to get hot. Being a resistor, it converts electrical energy to heat.

[Ray G.]

Re: Ballast Resistor gets hot suddenly

For peace of mind suggest you check everything you wired or rewired.
Are the engine and body properly grounded to the battery? Grounding cables all in place ?
Is the "large black ground wire end " at the battery on a starter bolt ? Not the positive cable of the solenoid.

[James B.]

Re: Ballast Resistor gets hot suddenly

All grounding at every location are in place, and all cables to the starter are correct. I have been driving the car without any issues now for two years after these components were refurbished and not touched the wiring since then. I guess during my initial investigation when I touched the bracket of the ballast resister, I did not realize how hot that they get. I am going to start up the car again and observe the wiring, and hopefully no more wire burning smell. Also, during my initial investigation, no smoke was observed.

[Michael G.]

Re: Ballast Resistor gets hot suddenly

Here's some assurance James, the ballast reisistor on my '63 gets 'purdy durn hot' as well.

[Dan D.]

Re: Ballast Resistor gets hot suddenly

Jim, do you have an IR gun so you can measure just how hot it gets? Then we can compare it to others.

-Dan-

[Stuart F.]

Re: Ballast Resistor gets hot suddenly

Dan;

Do you know whether the breakerless SE electronic ignition requires you connect to the resistor or not? My PerTronics II requires a full 12 volt input so I have to by-pass the resistor. At least check the specs in with the kit.

Stu Fox

p.s. no comment on my 63 crankcase explosion? That's ok. I just thought I'd throw it in (FYI) there for your consideration on your PCV connection.

[Duke W.]

Re: Ballast Resistor gets hot suddenly

The ballast resistor uses a special alloy wire that has an increasing resistance with temperature function. The late Dale Pearman referred to it as an "analog computer", and he was correct.

Worst case is if you leave the ignition switch on and the points are closed, which means the primary circuit has about 4 amps steady state current. When the engine is operating average current is less because the points cycle open and closed. The higher the average current, the more heat is generated by the ballast and coil, and the ballast is mounted in a ceramic housing because of the heat it generates.

Duke

[Dan D.]

Re: Ballast Resistor gets hot suddenly

Hi Stu,

No, I do not know for sure, but I think probably no. An electronic ignition is a completely different configuration, and probably uses the full 12V. Perhaps someone else can say for sure.

Hope you weren't offended by my dry humor this morning. Just feeling a little porky this morning and thought I would have a little fun. I know this was very serious for you and not funny in the least.

I am considering adding a flame arrester just to be on the safe side.

-Dan-

[Dan D.]

Re: Ballast Resistor gets hot suddenly

Yes, and this is known as a positive temperature coefficient. Resistance increases as temperature rises.

It is some type of a nichrome wire embedded in souer risen(sp?). An old compound used for securing parts and heat dissipation.

In a V8 engine the distributor indexes every 45*. Dwell is 30* or 2/3 of the 45 total. So the resistor is passing current 2/3 of the time.

Like I said, get an IR gun on it if you can.

-Dan-

[Jack H.]

Re: Ballast Resistor gets hot suddenly

The breakerless SE doesn't give a hoot about the presence/absence of the ballast resistor. Most of the other SS ignition systems need the full 12 VDC for them to power their logic circuitry properly. Hence you route a dedicated power wire to them that bypasses the ballast resistor.

The breakerless system manufacturers its own power supply rails inside the module using the complex waveforms that result from the switching action of power flowing through the ignition coil's primary side. This is why the breakerless is a 'single wire' system.

Also, the system is 'smart'. When the engine stops running (no tach pulses from the distributor), the breakerless module automatically turns OFF. That stops current from flowing through the ballast resistor and ignition coil primary which can/does happen in the conventional ignition system IF the engine happens to come to a halt with the ignition points closed versus open.

So, a selling point for these 'smart' electronic systems is many (including the breakerless) automatically thwart electrical stress on the ballast and coil when the engine isn't running and the ignition switch is left in the ON position.

[James B.]

Re: Ballast Resistor gets hot suddenly

Dan,

I do not have an IR gun, but a friend of mine has one. I will post the results as soon as I get it from him.

Jim

[Michael W.]

Re: Ballast Resistor gets hot suddenly

Dan,

I do not have an IR gun, but a friend of mine has one. I will post the results as soon as I get it from him.

Jim

Get ready for a surprise!