TR2/3/3A Pertronix on TR3 Ballast Resistor or no?

[newmexTR3]

Hey guys,

I have a question about installing a pertronix kit.. There are two options for installing it- one is if the car has a ballast resistor and the other is without. This is probably a stupid question, but I hooked it up as if my car didn't have one and it works fine, but I just want to double check.

DO tr3a's have a ballast resistor? What is it anyway?


Cheers,
Gavin

 

[martx-5]

You can check the coil itself to see if it should have a ballast resistor. The TR3's didn't require one originally, but just to be sure, remove one of the small wires going to the coil (either one), and check the resistance between the two small terminals. It should be about 3 ohms. If it's abour half that, then the coil requires a ballast resistor. The ballast resistor is in there so it can be bypassed when starting the car so the coil can generate higher voltages while cranking when battery voltage is lowered. During normal running, the resistor is in play.

 

[newmexTR3]

Btw, it's a Lucas Sport Coil.

 

[TR3driver]

Lucas Sports coils come in both flavors, both "external ballast required" and not.

As Art says, TR3s did not originally have ballast resistors (though mine does now). The resistor limits the current through the coil when the engine is running and battery voltage is high; but can be bypassed when starting to provide more spark when the battery voltage is low (cranking voltage can be as little as 9 volts). (I added one just so I could use a coil from K-mart

)

Most likely, if it's working fine, you are OK. But I'd want to check anyway, as the first sign that anything is wrong will be that the Pertronix quits working and has to be replaced.