ammeter needle flucuating / erratic bouncing 73 duster

[beerboy]

tech ?? here my 73 duster 340 ammeter gauge needle moves around from full 18 then back to 14.2 after car runs a bit needle hangs around 14.2 same with my after market volt gauge, battery is pretty new . fusible link is good , no heat issues around bulkhead. could it be alternaor going ? orange box regulator? u tube tells alot of guys to by pass ammeter, whch i get mixed answers with the more electrical type pros say as long as its the stock bulkhead and there are not a ton of add ons dont mess with a bypass.it probably isnt the gauge if the volt gauge is doing the same exact thing, this is frustaing as im no means and electrical engineer , any help would be appreciated thanks

 

[RustyRatRod]

If it's more steady once the engine is started and has run for a few minutes and going down the road, it's probably normal. When the engine is started, energy from the battery is used and the ammeter will show a strong charge until the battery recovers, then the ammeter will become more centered. Also when coming up to a stop at idle, some fluctuation is perfectly normal. It would still do you well to check all the connections going to and coming from the ammeter, including the firewall connector. You might even unplug them and clean the connectors, as this is sometimes a point of contention.

 

[67Dart273]

It's not where you simply have "more stuff" it's whether the bulkhead connector terminals/ ammeter wiring is damaged, ALONG WITH whether you have a much larger output alternator and of course more and heavier loads.

If the wiring is factory, and the ammeter and voltmeter are "jumpy" you need to get into it and examine it

One related "thing" that is rare but does happen, is that there is a factory welded splice in the black ammeter wire a few inches from the ammeter, all wrapped up in the harness, behind the cluster. That CAN break and will cause "jitters." First one I found was in about 1970-73 on a friend's 68RR in his apartment complex. We were both in the Navy in San Diego. Since then I've been privy to about a dozen of those failing, several members on this board

BUT THE VOLTMETER SHOULD NOT show anywhere near 18V. It should run right around 14

 

[4spdragtop]

Be very careful 18V is melting "stuff" territory.

 

[Oldmanmopar]

Take a temporary wire from the battery and splice into the blue wire going to the voltage regulator. That is what controls the voltage regulator. If the factory blue wire is not showing correct voltage. It will over charge and bounce. That would be a way to eliminate if its the harness. Many times the bulk head is compromised. or there is a break a the solder joint of the blue wires in the harness . That joint is located between the bulk head and the voltage regulator. Usually 4 wires soldered together . Could also be the ignition or the harness there. The Blue wire controls the regulator,

 

[CrazyBlaize]

make a shunt wire from the alternator to the battery. Does wonders.
If you want more info I can send you the video I watched.

 

[MOPAROFFICIAL]

Clean your cables and grounds, you may have a regulator going out or you might want to loosen retighten the bolts holding it and grounding it to the car. If the battery is good and it draws that much voltage to start ... your starter could be on its way out , putting out a bunch of resistance. You can test whether it's a battery issue or just the starter Itself by having the headlights on and starting it ..if the headlights dim a bunch then you know it's the battery, if they don't dim at all.. it's your starter.