Wiring a CA for 12V

First of all, one wire Alternators do not work well with early Tractors. Most one wire units need 1200-1400 rpm to excite the VR to charge. That means you rev the snot out of the engine to get it to charge. Tough on the engine. Change it to a 3 wire, where the Alt starts charging as soon as the engine starts. Most one wires can be changed to 3 wires.
Second- Alternator's, (especially one wires) should not be directly wired to the Battery. When the Tractor sits, the one wire Alt will draw on the Battery, eventually draining it.
Third- Alternators should not be used with Ammeters. Especially a 20/20 sweep OEM Ammeter. Use a Voltmeter in lieu of the Ammeter. Its safer. If you insist on using an Ammeter, use a 60/60 sweep unit, just in case a short develops on board somewhere and a king size draw occurs. That Alternator will smoke that 20/20 sweep Ammeter in a heart beat!
Lastly, CA's are usually Distributor fired. With 12V's, you need to establish 2.7-3.3 ohms of resistance in the Ignition circuit. You need to change the coil over to a 3.0 ohm coil with the 4 cylinder, and use an Ignition key to control power on board the Tractor to the Ignition. Don't forget to change the wiring around to Neg. ground. That means the - Neg side of the coil goes to the Distributor. OR you can purchase a wiring only kit from us (less the Alt) which gives you everything needed to wire the Tractor safely along with step by step instructions and color coded CAD wiring diagram. If you're gonna wire it yourself, do it the correct way. This way it makes the Tractor reliable, as well as safe... HTH
Steve@B&B

Put 12 volt on my B .It would not rev enough to charge . Run wire from alterator to dash to make it excite. Put a toggle switch on mine ,shiould have used push button. Crank  flip switch on and back off, will charge untill motor stops.Will run battery down if you leave switch on , reason for push button . Over two years and no problem.

I'll throw a twist in here. If you don't have lights then you really don't need a charging system IMO. Especially if you go to 12v. It will start your tractor maybe 50-100xs before it needs charged. Or like I do I just convert everything I own to mag and be done with the wires all together. I really don't like the alt conversions and would rather see a 12v genny. Personally I think the original 6v gen was perfectly adequate and I am very surprised at how bright my one CA is with the original bulbs.

Edited by wkpoor - 29 Jun 2011 at 8:33am

I really appreciate all the help. I may rethink the single wire alt theroy and go a different route. Thanks again, Nat

 Gerald, are you saying that is the switch has the acc position you don't need the diode or a lamp? My switch has 3 positions, the center is off, to the left is run and to the right is run and lights. It seems from your post that I don't need a lamp or diode, is this correct? Thanks, nat