When you get your meter, set it on DC scale and place the leads across the battery terminals. You should see between six and seven volts. Now, start the truck, bring it to a fast idle, and measure across the battery terminals. You should see an increase in voltage, up to 7 plus volts. If you see 7volts, you have a six volt generator. If the voltage measured across the battery is in the range of 10---13 volts, you have a 12V generator and can figure the system has had some kind of conversion to 12v. If you see the higher voltage, it will soon cause the 6v battery to boil. If you don't have a meter of your own, go to a hardware store and buy one. Cheap tool and necessary for playing with this old stuff. We wish you luck.

 

Ok I got a meter and just tested across the battery terminals. Tested a little above 6 without the truck running. I cranked the truck and tested again at fast idle and it went up just a tad but still below 7.

 

Doc, I am looking at the wire you pointed to in the pic above and don't see any designation of + or -

 

As I suspected, nothing has been converted to 12v except the battery and a light bulb. But to be sure, you need to disconnect the battery while it's running at +/- 1200 RPM and read generator output at the battery cables.

 

It will be cast into the top of the coil next to the terminal.

 

One terminal of the coil could say "IGN" and the other be the ground symbol.

 

The wire from the coil to the points is on the negative terminal.

 

If I understand what you say, that indicates someone has switched the wires as in partial conversion. In the stock positive ground configuration, the wire from the + side of the coil should run to the distributor which carries the circuit to positive ground when the points close. It will run either way, just not as well if reversed. IMO, don't worry about that right now although you can change it if you desire.

 

Jacnat, if you decide to go back to 6-volt, we can walk you through the steps involved. The only thing you'll have to buy is a 6-volt battery (Tractor Supply sells them) and whatever 6-volt bulbs (and headlights) that are needed. If you go back to 6-volt, I'd recommend that you go back to positive ground. You'll have to re-polarize the generator and possibly reverse the direction of the wire going through the ammeter.

 

Good discussion! My first time running thru an entire thread and I learned alot. I too am just starting a restomod on a 1948 Ford F-1 and this really helps me with my plan.

Thanks!

 

Yes, I want to second this. This discussion has helped me a lot. I plan to tackle my first big project soon which is to completely rewire my truck. It's encouraging to be able to ask a question and get this level of feedback from people who obviously know what they are doing. Thanks to all.

 

Not to muddy the waters but there is a 3rd alternative to 12 or 6 volt. You can install 2 - 6v batteries and a 12 volt alternator. This allows you to run all of your original gauges etc on 6 volts and all of your new accessories ( radio, AC etc) on 12 volts. Motor homes do this with 2 -12 volt batteries to run 24 volt systems. However, you still have to change over to negative ground.

 

Jancnat
Rewiring is a great way to get familiar with your truck. While there are harness kits available, you can replace one line at a time if you want to make your own. The Shop Manual and Operator's Manual have wiring diagrams with the color coding and guages. Be certain that the turn signals are correct - the turn and tail lights can be combined with dual filament sockets/ bulbs.

 

I have been following this thread, I just checked my truck and the wire from the coil to the distributor is on the negative poll......6 volt battery positive ground......does anyone recommend changing the coil wire?
Ed
near Philadelphia

 

Well.....considering you just made a thousand-plus mile round trip with that truck back in June, I don't really know what to say. It's supposed to be on the positive pole. I switched my dad's car back to positive ground once and re-polarized the generator. But I forgot to put the distributor wire on the positive pole of the coil. He drove it to town a couple times and shut it off. Both times, he was stuck sitting there for 20-30 minutes before it would restart. I turned it around, and it never happened again. I'm surprised it will restart after it gets hot. If you swap it, polarize the generator again just to be sure, and then watch your gauges.