Farmall C wireing

[BPDive]

I have a farmall c that was in desperate need of a rewrite had more bare wires then insulated so before I started I noticed that it was hooked up negative ground it starts and runs I polarized the generator and it seems to charge. My question is if the battery was hooked up backwards would it start and run or was it converted. Thanks. Bruce

 

[old]

+ ground or - ground they don't care unless they have been converted to 12 volts and have an alternator on them. Starter will spin the same way either way. Coil will work just fine either way and on most if polarized the generator will change the battery

 

[John T]

If battery polarity is reversed BUT YOU POLARIZE before starting (so you don't damage any Voltage Regulator if so
equipped) sure it can still charge.

The starter still turns the same direction regardless.

If it has an ammeter it needs its leads swapped or else it would read bass ackwards

If its a battery coil ignition the leads should be reversed to match the Ground, Pos or Neg, even if it still runs in the
wrong polarity. Its more efficient if the coil is wired correct, thats why it has those + and - labels

John T

 

[old]

Many coils I have sen don't have the + or -. Some do how ever say distributor or D on them but those have been one made for cars/trucks

 

[John T]

That's right Rich, I agree, Ive seen one terminal labeled BAT which is understood to get hooked to the BAT via a turned on ignition switch. HOWEVER in years of buying and selling (I was a used tractor dealer for years) and using hundreds of those darn old tractors, most (NOT saying all) coils have + and - terminal labels.

Take care Rich

John T

 

[old]

Yes the older ones on tractor did tend to have the + and - but the newer or replacement ones might have had bat on them if lucky and even then one cannot be sure what bat was saying as in + or -

 

[BPDive]

Yes I polarized before starting and when I rewired I switched the leads on the amp gauge and it did show that it was charging when I ran the throttle up showed a slight discharge when at idle. Being that it runs and starts should I leave as is or change to positive ground. Thanks
Bruce

 

[rustred]

john just told you. u wont turn his reply around to make yours right.

 

[John T]

Rich, Best I recall some of the old Farmalls are among those coils that were labeled BAT and DIST ??

John T

 

[old]

Yes but that did not fill in the big blank as in what the ground side might have been. Yes if say older then say 1962 + ground was the common thing but still it comes down to knowledge of things back then and now

 

[old]

So John. Here is a good one for you. Say you have a coil with no markings as to + or * side so how do you tell which is correct?? I know due to which way the spark jumps but few others are likely to know

 

[BarnyardEngineering]

(quoted from post at 15:41:26 04/12/21) Yes I polarized before starting and when I rewired I switched the leads on the amp gauge and it did show that it was charging when I ran the throttle up showed a slight discharge when at idle. Being that it runs and starts should I leave as is or change to positive ground. Thanks
Bruce

From a technical perspective it does not make any difference. If you want the tractor to be "original" then switch it to negative ground.

Some owners converted the tractor to positive ground, either because they didn't know any better, or to keep it consistent with everything else they owned.

 

[John T]

Rich, you sure ask fun and interesting questions, there is a way to determine the best way to connect a coil polarity (if not labeled). Ive seen video and pictures but cant find them. Here is basically how its done AS I BEST RECALL NO WARRANTY !!!!

You pull the plug wire about 1/8 inch off the plug,,,,,,,,,You place the very tip of a lead pencil lead in that gap,,,,,,Hook up the coil one way and cause that plug wire to fire (a bit in the dark helps) ,,,,,,,You will see a few carbon sparkies moving towards the plug or away from it,,,,,,,,,The CORRECT coil wiring polarity is that which makes the sparkies (electrons with a mass and carbon) MOVE TOWARDS THE PLUG

This is about Thermionic Emission in which its easier to emit electrons off a hotter to a cooler surface IE the reason vacuum tubes have a heater under the Cathode from which electrons are emitted to the cooler Anode/Plate....

In a spark plug the tip exposed to the combustion chamber is hotter then the plugs ground strap and the coil polarity should be so the electrons (charged particles having a mass) are emitted off the hotter tip to the cooler ground strap

There ya go Rich but remember NO WARRANTY this is my best recollection of videos and pics Ive seen explaining why coil polarity makes a difference and why its better if they are wired correct even if they can still spark if not.......

Take care my sparky friend

John T

 

[John T]

Its YOUR choice. The Correct Police (they can kiss my grits) like them original while many out there are so used to NEG
ground they convert them. EITHER WAY WORKS if you correct coil and ammeter polarity and re polarize.......

John T

 

[old]

The way I was taught was to watch the spark jump on a spark plug. If it jumps from the center area of the plu to the strap you open up to gap the plug it is hooked up correctly. If it jumps from the strap to the center part if is hooked up backwards

 

[John T]

Thats the same theory and is right but if you can tell just by looking (NOT using lead pencil) you have better eyes then I do

John T

 

[old]

Well my eye site is going down hill but that is pretty much normal as one gets older.

Here another one for you. If the ignition coil is mounted to the side of the block and say it has a thermostat that is 180 degrees doesn't the coil also get up to or close to that 180 and if it does one cannot hold there hand on it for more then a couple seconds?? Am I right on my thinking with this?? I know one cannot hold there hand on the side of a block after the engien has been run and hour or so

 

[Janicholson]

Just the reverse. originally it was positive ground. Some changed them to negative. if done including the amp gauge and coil, it will be
fine. Jim

 

[John T]

The 180 thermostat controls the temperature of the internal coolant, the block (or coil) isn't any 180 degrees just because the coolant is..The ambient temperature plus air flow and heat transfer cools that huge mass of iron moreso then the internally trapped cooling fluid.......

The physical location of the coil in relation to any hot surfaces like the head or block or especially exhaust manifold does contribute to the coils temperature as well as its metal mounting strap and how much heat it conducts away from the coil.

Its my experience sure a coil (subject to mount and location) will normally run HOT but NOT so hot you cant lay your hand on it. However if you apply 12 volts to a 6 volt coil it will get EXTREMELY HOT and may even boil out the nasty oil YUK

Best wishes Rich

John T

 

[John T]

Jim, I agree, it was my understanding most all the old 6 Volt Farmalls were originally POS ground but changed to NEG on or about the time they went to 12 Volts.....

John T NOT any Farmall expert but believe this is so......If polarity is reversed as you state change the ammeter and coil then re polarize and you should be good to go yayyyyyyyyyyyyyy

 

[old]

I have had a 6 volt coil explode because of 12 volts being put to them. Back decades ago I had a 196? VW bug that was 6 volts. I didn't know that at the time so had a 12 volt battery hooked to it. I had for some reason left the key turned on. My dad was walking by it and the coil exploded as he was. He said at first he thought someone had shot a shotgun close by till he saw the smoke coming out from under the hood of the bug. Talk about a real mess. Oil and wire piece all over the place under the hood of that bug. At the time I was 16-18 and was just starting to learn the internals of bigger engine then the lawn mower I had worked on. That is just one of a number of coils that I have had explode

 

[gene bender]

ORIGINAL WAS POSITIVE GND

 

[gene bender]

THE REGULATORS WERE POSITIVE GND

 

[John T]

Yep if it was POS Ground they would have used the correct POS Ground VR's to match.

John T

 

[gene bender]

the leads on the ammeter must have been changed also and it probably has a cut-
out because the reg doesent like the wrong polarity