6 to 12V conversion

This was posted on another site though maybe you could help


Converting my relatively stock 32 Model B 4 cal to
12v neg ground with single-wire alternator.

I have a 12v resisted coil from Napa, 12v bulbs, 12v distributor condenser, etc. No electric to gauges to worry about except dash light. Need to buy a higher capacity ammeter than the original 20 amp.

I'm trying to use a new original wiring harness I already had, and I'm going a little crazy in my hot garage trying to figure it all out since the printed diagram doesn't match the actual loom wires exactly(I think the diagram is more virtual then actual. The truck has been apart for years, so no existing wires to trace paths.

Attached is the service bulletin wiring diagram for the 4 cyl. I've got most of it figured out except for replacing the generator with the alternator.

Questions:
1. Does the new alternator single terminal get all the wires in the diagram that lead to the generator cutout? That is the YB back to the ammeter; the YR to the main light switch BATT; and the Y to the 12v horn?

If so, does the alternator charge the battery through the circuit running back to the ammeter and to the + side of the battery?

2. My 20 amp ammeter has the pass-through type of connector, not separate terminals, but my wiring harness has terminal connectors. I assume most/all new ammeters will have terminals? Is a 30 amp ammeter enough? I have a Nu-Rex 12v neg ground alternator, but it's been years since I bought it and don't remember the specs. Probably 60 amp max output or something.

I think once I know what to connect to the alternator, I can use a meter to trace the connections through the wrapped wiring loom to make sure I've got it all straight.

By the way, if it makes any difference, I have the foot starter rod, not the pull cable, so my starter switch mounts on the rear of the steering box and has two heavy gauge terminals on the underside.

Anyone willing to jump in? Also, please...let's not hijack this as to why I should stay on 6v +grnd.

Questions Questions, lets take them one at a time:


Questions:

1. Does the new alternator single terminal get all the wires in the diagram that lead to the generator cutout? That is the YB back to the ammeter; the YR to the main light switch BATT; and the Y to the 12v horn?

The main big single wire output lug could/would feed YES basically all (12 Volts) that was wired to the BAT side of an old Cutout Relay. That would be the LOAD (NOT Battery/Starter) side of the Ammeter,,,,,12 VDC to light switches BAT INPUT etc. Sometimes those loads are fed off the LOAD side of the ammeter but that's electrically the same as BAT on a Cutout Relay or the LOAD side of an ammeter. That's where the BAT on the cutout wires anyway but now the alternators main big output stud.


"If so, does the alternator charge the battery through the circuit running back to the ammeter and to the + side of the battery?"

The alternators charge gets to the battery to charge it VIA THE AMMETER. The LOAD side wires to the alternators output while the SUPPLY side gets to the batterys ungrounded post often where the big battery cable attaches to a starter switch or starter solenoids input. It needs wired at right polarity or would read bass ackwards.

2. My 20 amp ammeter has the pass-through type of connector, not separate terminals, but my wiring harness has terminal connectors. I assume most/all new ammeters will have terminals? Is a 30 amp ammeter enough? I have a Nu-Rex 12v neg ground alternator, but it's been years since I bought it and don't remember the specs. Probably 60 amp max output or something.

A typical new ammeter will have + and - terminals
which I call the LOAD (output and BAT on Cutout or new alternators output) and SUPPLY (input from battery) Sure ideally a 50 or 60 amp ammeter might be used but a 30 will suffice. It may peg for a short period after start up depending on battery condition. Trouble with a 60 is after start up the needle may not move much. A 20 amp may be a bit too small to handle an initial 50 or 60 amp surge but Ive used plenty of 30 amp meters on a 60 amp alternator never had a problem if you don't mind the needle possibly pegging after start up.


Anyone willing to jump in? Also, please...let's not hijack this as to why I should stay on 6v +grnd.

If you insist lol your tractor your choice NOT any of ours

John T

Thanks John,that will help him a lot