VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 6v Alternator Installation Questions

I am considering installing a 6 v alternator to replace the generator on my 1948 Chevrolet Fleetmaster Wagon. Any issues with the conversion? How do I wire the new alternator, do I need to do anything with the amp gauge. Any suggestions on vendors for the alternator and bracket.

Here are items to consider.

Is the wiring 3 wire or 1 wire?

Will the alternator will overload the ammeter enough to damage it?

I assume that any alternator you get these days is internally regulated. So you will need to bypass the regulator on the the firewall.

Does the alternator have the correct pulley to match your crank and water pump pulleys?

I've converted both my 38 and 53 to one wire alternators. I also converted my 53 to 12 volts. The smallest output alternator I could find is a 60 amp. The 38 is designed for a max of 30 amps. I did destroy my ammeter. I have a replacement if my son ever decides to go back to the generator. I put a 6v voltmeter under the dash in it's place. I believe the 53 is designed for 60 amps so it's not been an issue. You will need an alternator bracket because the generator bracket will not work. To bypass the voltage regulator with a one wire alternator simply disconnect all wires from the regulator except the BAT wire. Tape them together and ignore them. Connect the wire from the alternator to the BAT terminal on the regulator. You'll need a new belt. Keep in mind one inch length of the belt makes a large difference in the position of the alternator so you may have to make more than one trip to the parts store before you get the right one.

I have found a 37 amp 6v one wire alternator, will this damage the ammeter? How high of amp alternator before damage to the ammeter?

The 1948 standard 6 volt generator is rated at 36 amps. i would not expect a true 37 amp alternator to damage the ammeter.

If I install the 6v 37 amp alternator 1 wire will the ammeter still work? Is there any hints on how it should be wired?

Connect it the way I described and it will work normally.

. Put a shunt on the original amp meter. When it reads 20 Amps you'll know it means 60 but you won't burn it out. Chevrolet offered many generator options. In 1937, a 12 volt alternator was one of the options. One of my 37 Chevys has an original 6 volt alternator and designed for two 6 volt batteries in parallel.
. The first picture is from 1937 truck accessory book showing 12 volt option. .
. Second photo is a 1954 instruction manual showing how it's mounted.
. Third photo is my 37 Chevy with original working 6 volt alternator. They didn't have diodes in 1937 so you can see the rectifier plates in front of radiator. (Since it has air/hydraulic brakes, it has an air horn as well as electric horn.) .
. . Lou

Barring some catastrophic electrical short the gauge will be fine.
If you go 3 wire you can bypass it completely and use an idiot light.

This should clear up the mystery some...

http://www.madelectrical.com/electricaltech/onewire-threewire.shtml