positive ground

I assume you mean that the engine is not turning over after you finished the carb install?  With a 12 volt alternator, the negative ground would be correct.  Just switch the cables.  The starter will work either way, positive or negative.  If the starter still does not work, check all of the connections.  

yes, just like a truck... Positive to the starter lug ( assuming you have the old push rod/ starter switch setup... negative to ground..  Do you have a magneto or distributor ? Mag will start, no problem.. If its a distributor, you need a positive wire from key or on switch, to the coil, and a wire out of the coil to the distributor point... then it will start.

May also find that the way it is wired is draining your battery and that is why it won't start. My 12V WD has a cutoff switch on top of the key switch to keep it from draining the battery, and once tractor is started I have to pull the switch to engage the alternator charging.

I don't know about that, I just bought the tractor and found this trouble.

Reversing the battery polarity with the normal negative ground alternator (prescribed by SAE standard since about 1963) will run the battery down very rapidly and likely destroy the rectifiers inside the alternator.Neither is likely to survive.

Gerald J.

Somewhere I have a Delco manual on alternators and it admits making positive ground, but the SAE standard pretty much makes all easily found alternators negative ground. That SAE standard change came along about the same time as transistor radios. Tube radios survived wrong polarity, just didn't work sometimes. Transistor radios burn up transistors faster than the fuses blew.

I have  Leece-Neville alternator that has the negative post circuit insulated so it can be either polarity and there were some of those with external rectifiers to be easily used for positive ground. Its big, probably made for a truck, rated something like 130 amps.

Gerald J.

Okay, progress report on the B.  Gave up on the battery and got a different one installed.  Cleaned all the cable connection (especially the grounds) and tightened all.  It started right up but the alternator does not seem to be charging.  No great surprise there.  I have converted Cubs but never an Allis so if someone could post a wiring diagram for a single wire alternator I would be very grateful.  Since I have to have the choke about half open for it to run, I am thinking my used carb could use a good cleaning at the least.  Lot of smoke when it first started but I had added a half can of SeaFoam to about a gallon of gas so that is partly the reason for that.  It soon quit smoking but occasionally it would send up a small puff of white smoke.  What could be the reason for that?  Thanks for all the info and help from you guys.

The B and the C are VERY much alike, so hope this helps....
Here's one;



Here's two;



HTH's...... if not, just ask again and I'll see what I can come up with.

starter button with a solenoid to the battery.  Looks like a addon box with a button to twist  to turn on and twist further to start.  Never saw one like it before.

An ammeter is the best indicator of battery charging and discharging.

Gerald J.

Yes the voltmeter is very much easier to install. But in my experience (going back to adding a lab grade voltmeter and ammeter to my '64 VW) the information from the ammeter is much more benefit than the voltmeter. The ammeter shows the real current in and out of the battery (except for starter current) and shows that the battery is connected and is taking charge and when the battery current tapers to zero (with the proper charging voltage) the battery is fully charged. A voltmeter would be best if connected directly to the battery but rarely is and has to have two decimal digits precision to be of value. Connected anywhere else it shows the system voltage and when it is suppose to be charging that system voltage is nearly always higher than the full charge battery voltage simply because of voltage drop in the wiring. But the voltmeter unless connected independently to the battery posts can't detect if the battery posts are connected. And because of the voltage drop inherent in the wiring its impossible to detect if the battery is taking charge or is fully charged.

With a plug in voltmeter in the front accessory jack in my 2015 Fiesta SFE I'm finding the voltage varies from 12.4 to 14.4 while driving down the road. The wiring diagram shows its supposed to have power all the time. Very often soon as the engine is shut down the voltage drops to 12.4 volts but it should stay at 14.2 (12 volt battery full charged voltage) for a while only drooping from stray loads. Shouldn't drop that far in seconds. Just indicates there is voltage drop in the wiring between the battery and that receptacle.

Wiring the ammeter safely isn't difficult and hasn't any more fire hazards than wiring for the loads and the charging circuits.

I have three degrees in electrical engineering and was a registered professional electrical engineer in Iowa for about 40 years so I have a super electrical background.

Steve and I don't agree on the benefits of voltmeter vs ammeter. Until I can convince him the ammeter is the better instrument we sure won't agree.

Gerald J.

I can see why they used ammeters in the 40's and 50's. The tractors were equipped (as we all know) with the two position light switch to charge the 6 volt battery with a generator. How many batteries were "charged to death" when people left the button in the charge position forever?

With the introduction voltage regulators (either internal or external), most of us didn't care how much it was charging, as long as it was keeping the battery charged. A volt meter tells us a lot more. If I shut the tractor off yesterday and it is reading 13.5 volts and I turn the switch on today and the volt meter is reading 10.5 volts, I know I either have a heck of a parasitic draw or a battery that has a problem. All an ammeter would tell us is that is charging a lot, which is normal after cranking the engine.

If you are leaving a tractor completely original (6 volt generator with the generator cutout), an ammeter probably has some advantages. If you are upgrading to either a voltage regulator or converting to 12 volt and charging with an alternator, the volt meter has more advantages (to me).

Stan IL&TN wrote: Well since I'm a border line genius I like them both. Now can't we just all get along?

We aren't fighting, we're discussing. You get to do your tractor any way you like.

Over about 65 years around lead acid batteries, I don't remember one every going down with a shorted cell, but several had gone down with an open cell, and almost every one has had corroded connections. Hence my advice that 6 volt battery posts and connectors need to be cleaned to bare lead twice a year and 12 volt battery posts and connectors need cleaning every couple years. A voltmeter won't necessarily show these failures as well as an ammeter, and many automotive voltmeters do not have the resolution needed to detect charging or failure to charge. A voltmeter not connected directly to the battery can indicate a proper charging voltage but if the battery circuit is open from corrosion or a broken cable the battery isn't getting charged.

Then there is the voltmeter part of the dash of my '98 F150. It has two calibration marks, 10 volts and 18 volts, its not as useful as a light bulb for indication electrical system health.

Gerald J.

The most important think is that a standard alternator is for negative ground. If you hook up the battery positive ground, it will be discharging the battery.