fine tuning the charging system

[4404spdcharger]

I'm trying to get the last few quirks out of the charging system on my 68 Charger RT.  The system works OK except the ammeter flicks back to zero (or slightly negative) occasionally.  The charging voltage at idle is 12.5 V and increases to 13.9V at 2000 rpms or so.  I checked the voltage between the positive post on the battery and the alt output stud and it reads about 0.6 V.  not bad.  All connections have been cleaned and wire brushed (some were filed a bit) to get good contact, I sprayed and blew out with air the firewall connectors, and the fan belt is tight.  I've swapped out voltage regulators (no change) and the battery and generator are new (I know, no guarantees).  The ammeter reads positive (5-10 amps mostly) while driving above 2500 rpms but has the annoying flick back to dead zero.  I keep a battery tender on the battery at night so the battery is always topped off.  It looks like an intermittent or a loose connection but all are tight, double checked.  Any comments would be helpful.  Thx. 

[b5blue]

Check the back of the gauge connections.

[RECHRGD]

Unless your running an electric fan or high watt stereo, the ammeter should read right at or slightly above zero under normal driving conditions.

[Dino]

Check the back of the gauge connections.

Agreed

The gauge reading is within parameters but flicking back to zero implies that either the gauge has an issue or it loses continuity.  If one of the connecters is anything less than solid tight it can do this and as a result it can also burn that car down to the ground. 

Disconnect your battery and check the connections.  Also check the bulkhead connections, smother them in dielectric grease if you haven't done so.  Make sure the fusible link is  in place and the correct size as well.  If nothing changes then it may be the gauge itself.  Sometimes it needs a bit of tweaking as the needles are a real pita.  My oil temp gauge used to drop and come back up and it would repeat this over and over until I tweaked and recalibrated it.