I have a 1940ish ford generator on my flathead. it's a 6v positive ground car. I can get the generator to motor on my workbench. It makes about 7 volts at idle and will climb to about 14 when I rev it up. I just got a new voltage regulator from napa. I polorized the generator by disconnecting the field wire and touching the battery terminal for 1 second. when the car is running I get 7.8 volts at the arm post on the v.r. but just 6.0 on the bat post on the v.r. also when I raise the rpms the volts stay at 7.8 on the arm post , the volts dont rise like they do when the wires are disconnected and I'm checking at the generator. Why wont my battery charge? is the voltage regualtor bad ?
When I first installed my generator and Napa regulator I made a simple mistake that made my system have the same symptoms that you are having. Somehow I installed the regulator cover on backwards which made me hook the wires to the wrong terminals. I guess what I'm saying is, don't make the same mistake I did.