Ballast resistor

[airlifter]

Does my car have one and if so where is it located? It is a 69 TR6. I was adjusting the carbs this afternoon and the car had been running for a while at idle. It quit once and I suspected a fuel problem so I checked to make sure fuel was getting to the carbs. The coil must have cooled down while I was doing this because the car started.

In a few minutes the car quit again. I checked for spark from the coil and there was none. The coil was so hot that there was fluid coming out of the top.

The wiring diagram does not show a ballast resistor. The dist. Is a new rebuild from Jeff. The positive post on the coil is connected to 12v and the negative side to the points.
The coil is an Accel Super Stock from Universal Performance.
I read 4.7 ohms across the low voltage terminals. The car had a Petronix electronic ignition when I bought it but I changed it back to points.

Just a bad coil or other problems (I mean challanges)?

 

[poolboy]

Not until 1973 did the engines have a ballasted ignition.
It was just an additional wire attached to the positive terminal of the coil. The length and composition of that wire created higher resistance.

 

[airlifter]

Not until 1973 did the engines have a ballasted ignition.
It was just an additional wire attached to the positive terminal of the coil. The length and composition of that wire created higher resistance.

Any idea what would cause the coil to get so hot?

 

[poolboy]

I'm not familar with that Accel coil, but if it's one designed for a ballasted ignition, it will get hotter than normal..
You should have a 3.0 ohm coil such as the Lucas DLB 101 or the Lucas Sport coil DLB105 or the 3.0 ohm Pertronix Flame Thrower


If this is the ACCEL coil (8140) you have...it's the wrong one,

https://www.amazon.com/ACCEL-8140-Performance-Universal-SuperStock/dp/B00064P99W

 

[TR3driver]

There are several different models of Accel Super Stock coil; but AFAIK all of the "points" models require an external ballast. You'll need to either add a ballast resistor, or get a coil that does not need one.

Using a "ballast required" coil without a ballast means the coil is seeing twice as much voltage as it expects, which means twice as much current as well, for four times the power dissipation. That's why it gets hot. The heat will shorten the life of the coil and I've even seen it melt the points!

Your FLAPS should have a generic ballast resistor available. If you have to give them "make, model & year", tell them it's for a 1963 Plymouth Valiant.
https://www.rockauto.com/catalog/moreinfo.php?pk=933069

Seems like there is likely something wrong with your ohmmeter as well. Should be around 1.4 ohms for the "points" version, or 0.7 for the "electronic" version.

 

[airlifter]

The coil is the 8140 model. I will get a new coil tomorrow. Is there and advantage using the ballast resistor? I would rather stay with the non-ballast type.

I am considering going back to the Petronix ignition. Can I use the same coil for the points and Petronix?

 

[poolboy]

I know you can use the DLB 105 with the Pertronix and of course the 3.0 ohm Pertronix Flame thrower. Thats' the combination I'm using now.

Without getting too technical, the advantage to a ballasted igntion is that for faster engine starting, the coil is supercharged by feeding it 12 volts while the starter is being used..kinda like what you've been doing full time.
Then once the engine starts and the starter is disengaged, the ballasted wire feeds the appropriate lower voltage for that particular coil to produce spark.
You can google ballasted ignitions if you want and get into primary and secondary windings and all that stuff

 

[TR3driver]

Can I use the same coil for the points and Petronix?

Yes, in fact Pertronix warns to only use a "point type" coil. But if it is a ballast-required coil, then it still needs a ballast, with or without the Pertronix.

As poolboy notes, the ballast gets shorted out during starting. But the battery voltage is not 12v at that point, and may be as low as 6 or 7 volts on a really cold morning with a somewhat tired battery. The main advantage is easier starting in cold weather, for engines with a lot of smog equipment (that tends to make them hard to start). In general, unless you drive in weather well below freezing, I doubt you'll notice the difference.