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My 39 120 had been converted from 6 volt, positive ground to 12v negative with an alternator. When I rewired it, I changed it back to 6 volt positive and put a generator and a regulator on. I tested the engine, and it registered a negative charge, so I switched the leads on the amp meter, thinking that was the issue. I also grounded the regulator again. Still no luck - the engine shows a discharge when running at a fast idle, and if I disconnect the battery, the engine immediately dies. The generator was tested at the local shop and it showed that it worked well. The new wires are setup correctly to the generator.

Question - did I mess up the regulator? Or is there something else I need to be looking for?
Thanks

Did you polarize the generator after installing? If so, there may be more going on but if not, that is generally a necessary first step when a generator or regulator is changed.

FYI, dis-connecting the battery while the car is running is not a good way to check the generator. It can actually create a voltage spike and damage other components in the electrical system.

Assuming you are dealing with a local auto electric shop, I would take the generator and regulator to the local shop and have them tested together as on the car, 6 volt positive ground. If both check ok, I'd ignore the ammeter and get a volt meter to check the voltage. Report back and we can try and help you from there. Feel free to contact me if you want.
-Jason
Advanced Electrical Rebuilders
www.aerrebuild.com
jason@aerrebuild.com

Thanks - it helps to talk to someone who knows what they're doing! We have a good, old time generator shop here in Billings, who doesn't ask "Who makes Packard?" Would it help to check the voltage at the battery while the car is running? If I remember correctly, it should read more than six volts if all is well.

Check voltage at battery while not running should read 6.4 volts +/- a few tenths and should jump up to 7.5 volts or so once running/charging although any jump would indicate a charge of some sort.
-Jason
Advanced Electrical Rebuilders
www.aerrebuild.com
jason@aerrebuild.com

Hi - still having problems with the generator. I've checked the wires to the generator and regulator, and have installed a second ground from the generator to the bracket in addition to the stock one going to the screws on the regulator. I took both the generator and regulator to the local generator shop and both checked out and are working well. I touched the A post on the generator to the negative post on the battery for a second to polarize it just in case that was an issue. The car will start and run, but no movement on the ammeter; just stays on full discharge. I swapped the leads on the back of the ammeter, just in case I wired it up wrong. The ammeter will jump momentarily when I turn on the headlights, but then just goes back to discharge. I'm completely baffled. Any suggestions?

Jason, re-read your suggestion. Hooked up a digital ammeter to the battery, which read 6.5 volts (had the charger hooked up just before testing). Upon starting, the ammeter still showed a discharge, but the voltmeter went up to 6.92 volts.

Next question - can I take a modern ammeter and install it using the old face? I suspect that is my next project.

thanks

In post 6 above u indicated swapping ammeter leads and it STILL showed a discharge. Thetefore the ammeter is bad.

Ok, finally got the 39 out of the garage and out for a drive on a beautiful 54 degree day. Charged the battery up well the night before. Drove to my friendly mechanic's house and we installed a ammeter out of a 50 Chevy pickup, letting it droop below the dash. Testing it, we also checked out the battery with a digital voltmeter. The battery was reading just over 6 volts with the engine off. Repolarized the regulator and generator, but still barely any charge with the engine at a fast idle. My friend had a spare brand new voltage regulator on the shelf - we installed it and now things seem to be working ok.

The flack master is looking for a 39 junior series ammeter for me. If anyone else has one floating around, let me know. I can modify the Chevy gauge and make it look like the correct one, but that be a pita project. I would rather have a Packard one. I think the 39 and 40 gauges are the same.

I don't understand why the old regulator tested ok in the shop, but didn't on the car, but anyway the parts swapping worked. Thanks

David,
I may have a 38, 39 or 40 ammeter. I can't recall how the ammeter is built into the ammeter/fuel gauge.

I can look tomorrow.
Pat