The 1947 - Present Chevrolet & GMC Truck Message Board Network

Assuming that you're talking about a Chevy truck and your fabric covered wiring is in reasonably good condition.

1. Your 6 volt wiring is plenty heavy enough to accommodate the conversion to 12 volts.
2. You'll need to install either a 12 volt generator or better yet a 12 volt 3 wire internally regulated alternator with conversion bracket. (See#11 below)
3. Assuming you have the footstomp (6v) starter...no change is necessary...it will work fine on 12 v...just spin a little faster. Your current flywheel (6v) has 139 teeth....if you change to a 12 volt flywheel (168) teeth you would have to run a 12 v starter. If by chance you were running a car 6v solenoid controlled starter on your truck, you would have to convert the solenoid to 12v.
4. A voltage reducer (6v to 12v) would need to be added to your gas gauge. Available from most mail order Chevy truck vendors for less than $10.
5. All of your bulbs, including the instrument panel, dome lite, lighted heater switch, headlights, tail light (s) will need to be changed to 12v.
6. Your ignition coil will need to be upgraded to 12 volt. I prefer an internally regulated coil. I also add a 1955 up 12v condensor. The ignition points stay the same.
7. Your heater blower motor could be replaced with a 12v model or you could use a variable resistor to retain the same motor. I just disconnected my blower wire!!!
8.You'll need a 12 volt battery...your 6 volt cables, if in decent shape, are heavier than 12v cables so there is no need to change them out.
9. Your ignition switch, headlight switch, ammeter will work fine without modification.....don't forget to add the voltage reducer to the power (+) post on the fuel gauge.
10. Depending on the width of your current fan belt you may need to go with a 3/8" belt to accommodate the new alternator.
11. With the built-in regulator in the alternator you will need to run a heavy 10 gauge wire from the red lug on the alt. and tie in to either the starter switch lug or directly to the battery. The 3 wire alt has 2-14 gauge wires that need to run into the cab...one to the ignition switch and I run the other to an idiot light as an added safety feature. Your alt will come with some specific directions to where you tie into the ignition switch. The 2-14 gauge wires are marked "Field" and "stator" and go to a plug in the alternator that you need to purchase seperately. (Not included with a GM 3-wire internally regulated alternator) I use an alternator from a 77 Grand Prix, 8 cyl.,5.7 L..350R with a/c+HBL. from Azone.
12. On the firewall is a 6v horn relay that will have to be changed to 12 v. I upgraded to 12 volt horns. Don't think a 6 volt horn will last long on 12 volts.

Hopefully, I've covered everything.......you'll find that the conversion will give you much brighter lights and that the starter will really spin your engine over quickly. I also have added relays for the headlights and made a bunch of additional modifications to my little truck. Feel free to browse my webshots albums and fire any additional questions you may have. I hope this helps you get started on your conversion!!!

Dave