Just got a rebuilt flathead V-8 running and the generator isn't charging. We flashed the field by disconnecting the field at the voltage reg. and touching the battery terminal on the reg. I'm pretty confident in the wiring. We used a new wiring harness. I was thinking of touching the field with a jumper from the battery for just a moment while it is running at about 1000 rpm's. Then see if the voltage jumps above 6 volts. Then that would bypass the voltage regulator. Is that a bad idea? Does anyone have any advice? I might end up removing the generator and take it to a repair shop.

 

Generators have been known to wear and need rebuilding - mine, for instance. Have a shop rebuild it, after testing to check condition.

 

If You're sure about the wiring, then only the voltage regulator and the generator remains as a cause of not charging. I'd replace the volt.reg. at first and try
it that way. If this doesn't work, You'll have to repair or to replace the
generator.

 

If you've rebuilt the motor, it stands to reason you don't want a clapped out generator on it. One option: Take it to a motor shop that has experience with automotive generators. Want a fresh voltage regulator as well, solidly grounded. Not the new manufactured junk, find NOS, or maybe the shop you took the generator will have good used. They can spool up the generator and regulator together on the bench and adjust cutout, voltage, and current settings so they will work perfectly when installed.

 

Try introducing a slight bit of vibration onto the case of the VR and the generator while the vehicle is running. The VR points may be stuck or corroded or the brushes in the generator may be stuck. No guarantee either of these procedures will work but they are quick and cheap. A screwdriver handle on the VR and a hammer on the generator would be my tools of choice.
Search for "generator testing" for a quick test. The tests involve what you mention and testing the generator to run as a motor.

 

That's a good point. Recently I bought a new one and after installing I found out it didn't work. When I opened that part I was surprised to find one of the bimetallic strips mounted upside down, meaning the wrong way. Now I know why they sell theese parts for under 20$

 

I would follow the test procedures in the Ford shop manual. That might be the procedure to full field, but I can't recall. Generator tech is real simple but different procedures are used depending on the type of system. GM and Chrysler is different than Ford, and most of us don't have generator troubleshooting procedures commited to memory. Using the procedures designed for type "A" generators on type "B" can let the magic smoke out of the regulator.

 

Hello Krustiy; what your suggesting is on page 250 of the Ford (48-51) manual except they use a ammeter to check for output of the generator. If your battery was sitting at say 6 volts and when you did the jump it went up to 6.7 your generator is working. Wiring or regulator left to be the problem.