The Ford Barn - View Single Post - difference in 6 volt and 12 volt ignition ?

Mike51Merc · 11-15-2020, 05:04 PM

OK, so I don't want to get into the weeds of electrical theory, but a resistor doesn't limit or reduce current, it limits or reduces voltage.

You cannot use 6volt coil for 12volt system or the reverse. Well actually you can and it might work poorly or fry the coil, but that's your choice.

Coils are rated in ohms, which is the measurement of resistance. Typically you want a coil around .5 ohms in a 6 volt system, and around 1.5 ohms for a 12 volt system.

Ballast resistors are used to lower the voltage to the coil, and most particularly to the ignition points, because points last longer with lower voltages. In theory, you could use a 6 volt coil in a 12 volt system if you used a big enough resistor to lower the voltage from 12 to 6, but again, that 's not the best way to build an ignition system.

11-15-2020, 05:04 PM	#5
Mike51Merc Senior Member Join Date: May 2010 Location: Northeast Pennsylvania Posts: 1,582	Re: difference in 6 volt and 12 volt ignition ? OK, so I don't want to get into the weeds of electrical theory, but a resistor doesn't limit or reduce current, it limits or reduces voltage. You cannot use 6volt coil for 12volt system or the reverse. Well actually you can and it might work poorly or fry the coil, but that's your choice. Coils are rated in ohms, which is the measurement of resistance. Typically you want a coil around .5 ohms in a 6 volt system, and around 1.5 ohms for a 12 volt system. Ballast resistors are used to lower the voltage to the coil, and most particularly to the ignition points, because points last longer with lower voltages. In theory, you could use a 6 volt coil in a 12 volt system if you used a big enough resistor to lower the voltage from 12 to 6, but again, that 's not the best way to build an ignition system.