In Reply to: UN converting 12 volt posted by Zeke Central Oregon on April 19, 2022 at 11:43:30:
The Ford original electrical system was 6-volt/positive ground and works fine. Many have been switched over to the 12-volt/negative ground system and works fine as well. There are PROS & CONS to each system and either one will work fine PROVIDING they are wired correctly. That is the problem with a lot of folks. They don't know how a 6-volt system is supposed to be wired and then have non-starting issues. Ditto with a 12-volt system too. 99.98% of all non-starting issues are due to incorrect wiring setups regardless if 6V or 12V. You can get a wealth of information in the How-To's forum here, under electrical to start with. Scroll to Wiring Pictograms by JMOR and download a copy as he has shown how to wire these BN's correctly in both 6V and 12V. You also need to search for Bruce(VA)'s documents and posts. 75 Tips is a starting point. All 9N and 2N models after 1940 were wired the same: 1-Wire/3-Brush 11A generator, a roundcan cutout circuit, and a 1-Wire Starter Motor with no solenoid. The 8N model went to a 3-Wire/3-Brush, 11A generator (at first) that used a voltage regulator. The Starter Motor was a 3-Wire model that now used a solenoid. All 9n, 2N, and early 8N's (til 1950) used the front mount distributor. This has been a confusing part for a lot of folks and if not done right will cause problems. Guys screw it up and can't start so figure they have to go to 12 volts then end up with the same problems. The 8N after 1950 went to a 2-Brush/20A generator and a side mount distributor that were big improvements. Unless you have an early 9N or early 8N that you want to restore to all original, and your tractor now has a 12 volt setup, I suggest to leave it as is and verify it is wired correctly. Start with the correct battery. Verify wiring by the diagrams without the battery connected. One mistake folks make using both a generator and an alternator is they fail to have a fan belt tensioning device attached. Without proper fan belt tension, your system will never charge the battery. When all is right with world, invest in a Battery Tender to keep it at 100% at times when not running. Tons of info here in the archives and How to's.