g741.org

Well now being poor folk, I rewired the ol' MayWalk by making my own harnesses, using fuses instead of the original breakers (Yea I know...sacrilege, but I have done a bunch, and it was way cheaper). After a little head scratching, I realized that I did not see a ballast resistor in the old and much deteriorated although still intact harness... so I did not include one in my distributor wiring. I guess my question is... Should there be one??? If so what type of "off the shelf" resistor should I use.

I think you'd only need the ballast resistor if you swapped voltage fro 24 to 12?

Very early 37's ( 1951 ish) came with a seperate ballast that sat under the ( short ) coil but I doubt you'll ever see one as the military went to a (longer) coil with a internal ballast resister soon after. So to answer your question there is no inline ballast resister, its 24v to the coil

I blew a 12v coil on mine by failing to install the ballast resistor when I rewired mine with the Painless kit. It smoked and sprayed fluid all over the driver's side of the engine compartment. $30 for a new coil and readding the resistor solved the problem (which was my own stupidity....)
Gary

My 2cents: If you are running a 12 volt system then just buy a 12 volt coil. and no resistor is needed. I have been running a 12 volt coil for years in my 75 bronco. Works great.

I believe if an external ballast resistor is used in a 12v system a 9v coil is being used. During start up the ignition switch shorts out the resistor sending 12v to the 9v coil for a hotter spark to start the engine, after start up the resistor is back in the circuit running the coil on 9v and unstressed. A 12v coil will need no ballast resistor but will have a weaker spark at startup.
Greencom

The standard coils over the years have been the nominal 6 V and 12 V (either 12 volt with builtin resistor or 12 volt with tag "Use with external resistor)(the secong is reaaly just a 6 volt coil). I never heard of a 9 V but you are probably thinking the actual rating of the standard 6V coil is really 8 volts. 12 volt systems really don't need the extra punch of a unresistored 6V coil during startup since they turn the engine faster than a 6 volt system leaving plenty of voltage over for the coil. I think most of the early 12 volters (1950-60) just figured it was easier to just add the resistor then confuse the coil listings.