What is this wire

I have rewired my 51 8N one wire at a time, restoring needed items, but seem to have an errant orphan. It looks to be a ground. It attaches to a screw in the back of the dash, but where does the other end go ? This 8N has a one wire alternator and a ballast resistor. Instead of a terminal block I put everything except the positive battery wire on the negative side of the ammeter. Thanks for the help.

It may have provided ground to the old voltage regulator.

That makes sense, Jim, it doesn't have a voltage regulator anymore, and the PO wasn't very tidy, concerned or meticulous. I replaced the light switch because someone had cut a piece of copper tubing and jammed it into the light switch where the fuse should have been. So I'm trying to undo the stupid as much as I can. Thank you so very much for the help. I'm very grateful.

A 51 would not need a ballast resister, maybe an inline resister if you still have a 6 volt coil. I got rid of the 6 volt coils and went with napa 12 volt coils, no register needed.

Your 'extra wire' is no doubt from a previous incorrect wiring job. A '51 8N would have the angle (side) mount distributor and thus NO Ballast Resistor in the circuit. Don't confuse the OEM Ballast Resistor with an external white ceramic 1-OHM resistor -they are not the same. The OEM Ballast Resistor is only used on the square-can coil front mount distributor. There is a junction block that connects a few wires. Did you go with a good wiring harness or are you as you say replacing each wire one by one? On an 8N 12V switch over job, you take the Generator and Voltage Regulator out of the circuit and replace with a an alternator. Your 12V batter should be a GRP 25 or GRP 35 robust brand and with new, correct 12V battery cables. Don't use the OEM 6V cables. The OEM AMMETER was the 30/30 Induction (LOOP)style. OEM wiring will show wire feed. Aftermarket AMMETERS have two screw terminals. There is no polarity but if you mean when reading a charge it is backwards, simply switch the wires around or feed the wire the other way if a LOOP style. Just to be clear, your 12V battery and alternator should be wired with a NEG GRN. See if this helps:

FORD OEM BALLAST RESISTOR -USED ONLY WITH FRONT MOUNT DISTRIBUTOR:

HELP: The LH resistor Terminal Post connects to the COIL Stud Terminal Post as you face the back off dash. OEM Wiring is RED.

FORD 8N TRACTOR EARLY OEM DASH PANEL WIRING, RESTORED:


EXTERNAL 1-OHM CERAMIC RESISTOR - USED ON FRONT MOUNT ONLY AND
ONLY IF COIL IS 6V:


FORD TRACTOR AMMETERS ? LEFT -OEM INDUCTION/LOOP STYLE; RIGHT ?AFTERMARKET SCREW TERMINAL TYPE:


CORRECT FORD 8N ELECTRICAL SYSTEMS - 6V & 12V:


*PICTOGRAM courtesy of JMOR


[i:654c4848f0][b:654c4848f0]<font size="4">Tim *PloughNman* Daley(MI)</font>[/b:654c4848f0][/i:654c4848f0]<table width="100" border="1" cellpadding="0" cellspacing="0" bordercolor="#000000"><tr><td height="25" colspan="2" bgcolor="#CC0000"></td></tr><tr><td></td><td></td></tr></table>

Oh boy - I'm in over my head here. I believe you're right. It is the ceramic resistor. It has been converted to 12V, there is a side mount distributor and the mounting block is gone. Only the screw holes remain. The said "extra wire" is long enough to reach the headlight on that side so who knows ? I did the one wire at a time because I had the spool of wire and no $. I can see that I put entirely too much faith in the PO, although it was running......Thank you for the photos. I am so grateful for you taking the time to send pictures and advice, and sitting on a bucket next to me here in the barn. I need it and this is a very kind thing to do.

I used the 3rd wiring diagram shown, with the voltage regulator in the "delete" box in the center. Another advice post said you can skip the terminal block and just wire it all to one side of the ammeter so that's what I did since my terminal block is absent. Does this diagram make the ground correct ?

Tim ,where do you get redone original style regulators?looks great.Paul