1948 Ferguson TO-20 Electrical System

[Randy Roberson]

Hi, I'm finally getting my tractor running again, now that the weather has cooled off. The electrical system was converted to 12V negative ground some years ago, and it is about 1/2 missing. There is a solenoid switch mounted on the battery tray, and a ballast resistor in the circuit to the ignition coil. Rather that spend time restoring it to positive ground, etc. I am just trying to get her running for now.I have bought and installed the reproduction switch which is activated by the shift lever, and I plan to use it in place of the old starter button, along with the solenoid, so at least I will have the neutral safety feature this provides.
What is the correct polarity to install the ignition coil for negative ground: neg to dist, or pos to dist? I think neg to dist, is this correct? It is a 12 Volt coil.
I also am trying to connect the ballast resistor bypass on the solenoid for more ignition voltage during cranking: is this as simple as it looks (connect this terminal on the solenoid to the coil side of the ballast resistor)?
Also, I will probably do away with the key switch (On-Off) as it is broken, and use a toggle switch. Any problem, functionally speaking? I might include a pilot lamp as a reminder to leave the switch off. Depends on if I get her running pretty soon, etc. Thanks for all the advice!
 

[old]

The points ground the coil so when it does it fires the plugs so what ever side of the battery ground that is in turn the same for the coil. So yes + on the coil goes to the distributor
 

[Randy Roberson]

Ok, thanks, I should have put this in the Ferguson section; sorry.
 

[Jerry/MT]

The primary wire running to the distributor from the coil should have the same sign as the battery ground. In your case 12V (-), that means the primary wire to the distributor from the coil should be on the coil(-) terminal
 

[old]

I did sort of say things back wards. When the points open is when the spark fires off but other wise the coil is grounded. As for which forum as long as you get your answers what does it matter
 

[JMOR]

[Randy Roberson]

Solenoid has two high-current (large) terminal posts: one from the positive side of the battery, and the other from the solenoid to the starter. It has three small posts: one goes to the key switch, then to the ballast resistor, to power the ignition; one activates the solenoid by giving it 12V from the pos battery post, and usually the third one is a ballast resistor bypass. It becomes energized when cranking (when the solenoid is energized) and sends the full 12V to the ignition system, bypassing the ballast resistor, so the ignition has more power for starting.
Looks like it was not connected and all the ignition was going through the ballast resistor all the time, so it may not be necessary. You used to see this setup on Ford products.
 

[Randy Roberson]

I may have it wrong, I'll look at it when I get home and see how wrong.
 

[JMOR]

[Randy Roberson]

My tractor;s solenoid has two large terminals adn two small. One of the small terminals should connect to the "crank" switch adn will activate the solenoid and starter when it gets 12V. The other small terminal becomes energized with 12V when the solenoid is activated (i.e while cranking) and should be wired around the resistor in the power circuit to the coil; purpose is to provide a temporary hotter spark while cranking. the solenoid grounds via the body and contact with th etractor frame where it is attached.
I think I have it now.
Thanks, everyone,
RR