ballast resistor

kenneth house · Dec 27, 2011

when converting from 6 to 12 volts, it is said to install a ballast resistor before the coil. why is this necessary?

Wayne in MN · Dec 27, 2011

To "resist" the extra voltage to the points. Using the original 6 volt coil, the higher voltage will rapidly burn your points unless a resistor is inserted in the circuit between the switch and coil.

Use a 12 volt coil with a built-in resistor and you should have no troubles.

Janicholson · Dec 27, 2011

With respect, there are no built in resistors in 12v coils. The coil is just designed for 12 volts not 6. It is a common issue, but needs to be correct. The coil should say "for 12v no external resistor required" on it or the box. Or use the original coil with a Mid 1960s chevrolet ballast resistor. Jim

old · Dec 27, 2011

A ballast resister drops the voltage down to the level that the coil was made to work at so you get the faster spinning of the starter but at the same time limiting the voltage to the coils so as not to burn up the coil which in turn can/will cause the points not to last as long

mkirsch · Dec 28, 2011

(quoted from post at 16:09:57 12/27/11) With respect, there are no built in resistors in 12v coils. The coil is just designed for 12 volts not 6. It is a common issue, but needs to be correct. The coil should say "for 12v no external resistor required" on it or the box. Or use the original coil with a Mid 1960s chevrolet ballast resistor. Jim

There are also so-called "12V" coils that REQUIRE a ballast resistor. You can purchase them right off the shelf at Tractor Supply even. Says right on the package, "for systems with external ballast resistor" or something like that.

Supposedly this was to alleviate confusion about whether the coil would work on a 12V vehicle. The coils were all 6V, but 12V vehicles had a ballast resistor hidden somewhere to reduce the voltage.

greyfoxxca · Dec 28, 2011

Use the original coil with a ballast resister with a bypass of the resister on the starter circuit. You will get hotter spark when starting.

good luck
George

ballast resistor

kenneth house

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Wayne in MN

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Janicholson

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old

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mkirsch

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greyfoxxca

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