Coil points 12 or 6 volt

I have gotten several answers to .. what kind of coil to use
Some say I need a ballast resistor on a 12 volt coil for 6 volt - others say
all 12 volt coils have a build in resistor ..
also .. I am thinking of putting Petronix electronic ignition in my Jubilee which is
converted to 12 volt already .. . it has a 12 coil and alternator on it now.
Do you for see any problems with using the Petronix electronic ignition .. I have the
parts for the 4 cyl Ford Jubilee ..
any info would help .. (especially about the 6 volt system and what kind of coil) please
Gary (gdtractor)

(quoted from post at 11:12:18 06/14/21) I have gotten several answers to .. what kind of coil to use
Some say I need a ballast resistor on a 12 volt coil for 6 volt - others say
all 12 volt coils have a build in resistor ..
also .. I am thinking of putting Petronix electronic ignition in my Jubilee which is
converted to 12 volt already .. . it has a 12 coil and alternator on it now.
Do you for see any problems with using the Petronix electronic ignition .. I have the
parts for the 4 cyl Ford Jubilee ..
any info would help .. (especially about the 6 volt system and what kind of coil) please
Gary (gdtractor)

Click to expand...

Some 12v coils require an external ballast - consult the catalog or data sheet for your particular coil.

EI is a hot button topic with ardent proponents an opponents. It is fundamentally a matter of personal preference. It won't turn an NAA into a powerhouse nor will it turn it into an unreliable paper weight.

TOH

See tip # 30.

No automotive coil has an internal resistor. Internal coil resistance is determined by wire gauge and the number of turns. Higher resistance is provided by smaller gauge wire with greater turns. If the coil is marked or sold with a notice requires an external resistor that simply means it has a low internal resistance and will be damaged by excessive voltage. It does not mean the coil has an internal resistor. Yes, plenty of coils are advertised as having an internal resistor. Thats called advertising, not electrical engineering. To be both accurate and precise, every automotive coil should simply state the internal resistance of the coil. But that would require a basic understanding of the Kettering Ignition system. So to keep it simple, ANY side coil with an internal resistance of 3.25 ohms will work fine on your 12 volt NAA w/o any external resistor. Like the NAPA coil, p/n IC14SB. Many folks just add a 12 volt coil rather than dealing with trying to find an external resistor to work with their existing 6v coil. Too much resistance gets you a weak spark; not enough and the coil melts.

The key advantage to EI is that you do not need to gap & lube the points every year & replace them every 4 or 5 years or. If you perform annual maintenance on the points & change them every 4 years or so using quality parts, you will see no difference whatsoever between a points ignition system & EI on an NAA. The key disadvantages to EI on an NAA are initial cost, nearly impossible for the average owner to repair, will not work w/ low battery voltage, & easily damaged beyond repair by polarity reversal & other common mistakes If you have a well running tractor & just don't care to fool w/ points anymore, EI is a perfect alternative. If you expect EI to cure any significant ignition problem you may have other than bad points, it won't.
75 Tips