Slight electrical issue with our B... Need help

How to wire it, depends on the alternator you have. This would be best to delete the resister and use a 3 ohm 12 volt coil. It also gives a recommended wire size. The warning light can be replaced by a diode but I don't know what diode.



Edited by CTuckerNWIL - 06 Jul 2016 at 6:59pm

You need at least 8 gauge for a 50 amp alternator, preferable 6 gauge. The original generator wire can't stand the heat from the alternator current and has melted the insulation.

The power wire from the alternator (presume negative ground as positive ground alternators are uncommon) goes to the + terminal on the new 60-0-60 ammeter. Another piece of the same large gauge wire goes from the negative terminal on the ammeter to the battery positive probably at the starter switch connection to the battery.

Then to excite the alternator without spinning it fast, you will want a wire from the ignition circuit to the proper connector on the alternator with an indicator lamp, a resistor, or a diode to keep that circuit from backfeeding the ignition circuit and preventing it shutting down by merely opening the ignition switch. Providing you have a distributor ignition not a magneto. That's not a problem with the magneto but you need a switch to apply initial power to the alternator. It could be a momentary push button or a switch (not grounded) that was closed by rising oil pressure. I know NAPA has such a switch.

Gerald J.

step 1) remove 100% ,yes ALL, of the original wiring

step 2) buy a harness from Steve at B&B and install

step 3) have fun for the next 50 years and NOT have wiring 'issues'!

Now you can wire it yourself but by the time you get the proper wire,connectors, 2-3 pots of coffee and all the TIME spent redoing this end or that end you'll actually SAVE coins by going to Steve. I've rewired 3 of my 4 D-14s and it's an all day job to do it right. Not a lot of wires but weaving them in and out, checking lengths, oops, too short, cut anothter,dang STILL too short....well, you get what does happen. Life is too short.

Jay

You might need to do some other wiring because you have a distributor...... 

If you use a 10 gauge wire on a 60 amp 10SI you need to use silicone insulated wire because PVC insulation won't handle the high operating temperature from the current even when limited by the wire resistance. That's what I did with my 4020 and the wire size definitely limits the peak charging with the one wire alternator with the voltage sense terminal connected directly to the output post of the alternator.

The charging current would be greater (and so faster) if the voltage sense terminal of the 1 wire alternator was connected near the battery to compensate for the voltage crop in the power wire, but then that power wire will need a NEC current rating equal to that of the alternator, like 50 or 60 amps to keep it from overheating. Its likely to be close to the hot engine block which also tends to melt low temperature wire insulation. The worst place is near the exhaust manifold. Silicone fiberglass wire is a good option.

Gerald J.