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I took my car for a 54 mile ride to the upholstery shop and the ammeter needle was left of center all the way there (discharge). The headlights, radio and heater motor were not on. The wiring is all new and I doubled checked the connections to the ammeter. Dielectric grease was used on all the wire connections. I did a bench check on the ammeter and it works correctly. The battery is brand new - manufactured 9/20. The positive battery cable is heavy duty gauge #1 (Filling Station #SA-101). The ground cable is also brand new. There is a brand new AC Delco 35 amp voltage regulator (Chevs of the 40's #1118301A). The generator was rebuilt and tested by a professional. When I get the car back, I was going to install the old voltage regulator to see if that will solve the problem. One thought is to adjust the new voltage regulator, BUT, I never did that before and I am very concerned about damaging any of the the new components. Any suggestions?

Was it charging before the trip to the upholstery shop?

If this is the first time it has run since you installed everything... you may just have the ammeter wired in backwards.

If it was charging before... your cut out may not be closing. If this is the case, give the cover on the voltage regulator a sharp rap with the handle of a screw driver while the engine is running.
If it starts charging again... shut the engine off and try again. If it doesn't charge... check the voltage at the gen/arm terminal of the regulator. If it's low you have a generator problem (probably brush related). If it's within spec... your cut out adjustment may just need a little tweeking, the points on the cut out may need a little polishing, or you may need to replace the regulator.

There are lots of things that could be wrong, but these are the most common.
I can't tell you the number of times I've seen a sharp rap on the cover of the regulator "fix" a charging problem.

Either the generator is not charging or the voltage regulator is defective. Do not screw around with it. See the generator section of the shop manual to see the simple generator test.

Did you polarize the generator after putting it back on?

Dave

Excellent question!
One of the easy things often missed.

I touched a wire to the Bat terminal and the Arm terminal briefly on the voltage regulator. I thought that polarized the charging system. Never heard of polarizing the generator. How is that done?

there's no such thing as polarizing the charging system.
When you flash ARM to BAT you are magnetizing the Arm with a little residual magnetism that serves to get the generator started making power before the regulator takes over.
You can test your meter hookup by turning on the headlights, engine off, and observing the meter deflection.
It should go left, to indicate discharge.
WL

Respectfully Wilson, I beg to differ...

You DO polarize the generator, but it is the FIELDS you polarize, not the armature.
The direction you run current through the fields will determine the north/south orientation of the residual magnetic field you create. It MUST be the right way.
If you touched bat to fld on the regulator you would magnetize the fields... but the wrong way. The generator will then try to start charging in the WRONG direction.
You are right that the residual magnetism gets the generator to start charging, but it is the generator itself that takes over as it starts pushing current through it's own fields. Not the regulator.

Hawkeye...
You did the right thing.
Even though you do the deed at the regulator... what you are doing is polarizing the fields in the generator as above.
When you did what you did, you sent current from the battery back to the armature terminal on the generator. The fields take their current from that terminal but INSIDE the generator, run it through the field coils, out the field terminal on the generator and back to the regulator, through which it is eventually goes to ground. What goes on inside the regulator before it gets to ground is another story for another day.
Remember this... you need to run current through the field windings the same way it will go when the generator is charging to create a magnetic field with the polarity that will then start the generator charging in that direction when it is restarted.

To be more precise...

It is the poles or pole shoes that the field windings are wound around in the generator that we are magnetizing.
And magnetizing with the right north/south orientation so the generator will start charging in the right direction.
Remember the "right hand rule" of electromagnetism? :-)

Also...

Voltage regulators can not be polarized or re-polarized. The cores in them do not hold "residual" magnetism. If they did, they wouldn't work.
And contrary to what some people say, you can not use a regulator designed for a positive ground system on a negative ground system or vice versa.
The cut out will not work.

Indeed the lack of polarizing is a common problem with charging systems that have been disturbed and there are many past posts about it. Here is a link to an early post that covers it and the Delco process:

https://vccachat.org/ubbthreads.php/ubb/showflat/Number/45175/Searchpage/7/Main/6507/Words/%2Bpolarizing+%2Bgenerator+/Search/true/re-polarizing-the-generator.html#Post45175

I appreciate all the information. Needless to say, a lot of it is giving me the "deer in the headlights" effect. When I get my car back, I will run a test on the generator and see what is going on there. If that shows the generator is charging correctly, then I will install the old working voltage regulator. Start the car and see where the ammeter is at. Then turn on the headlights and see what that does. I'm a visual guy who needs pictures or the real part in front of me to make sense of things. Thanks again for the information.

Unfortunately just because a part is "new" does not necessarily mean that it is "good". Especially if NOS or a battery. Batteries are consumable so if you get a bad batch or just old stock, it can run you in circles so always check the most obvious things from scratch as though you've never seen this car before...