I am submitting the following paragraphs, on ballast resistance, that are
located on the http://www.cranecams.com website for review before submitting
them to the TR FAQ. If the list does not believe further explanations are
required, please let me know.
BALLAST RESISTANCE: All vehicles with original equipment ignitions are
factory equipped with ballast resistance. This can be found in the form of
a ceramic ballast resistor or a resistance wire between the ignition key and
the coil terminal. It can also be found in the form of internal resistance
within the coil, such as Lucas coils found in older British cars.
HOW CAN I TELL IF MY VEHICLE HAS BALLAST RESISTANCE? Run engine at fast
idle and measure battery voltage, between the two terminals, with a
voltmeter. It should be about 12 plus volts. Then measure the voltage at
the coil plus terminal and the negative terminal of the battery (or ground
to the engine or chassis). If there is a difference of more than three
volts, a ballast resistor is present.
CHANGING COILS: If you are changing coils and your original coil has
internal resistance, you must add a ballast resistor to the new after market
coil. Use a volt/ohm meter across the two terminals of the original
equipment coil. Coils with internal ballast resistance will read three or
more ohms.
I know Dan Master has a pretty good explanation on the TR FAQ. Maybe the
above will add to his explanations.
I am submitting the above to help novices like me get a better understanding
of coils and ballast resistance.
Martin
73 TR6
San Jose, CA
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