electrical issues, dimming lights, occasional stalling, rough idle at stop

Evan Frucht said:

Ok I identified another voltage drop that isn

New ignition switch did not fix it. A voltage drop test is a very similar test to a resistance test. Bas9ically instead of measuring resistance when the wire has no current passing through it. You measure the difference in voltage between two points on the same side of a circuit while the system is under load (such as car running or a switch on.)The reason I was told to so a voltage drop instead of a ohms test is that supposedly wiring can sometimes pass an ohms test but then fail a voltage drop test. So a voltage drop test is actually better at showing you if voltage is getting "stuck" anywhere in the wiring or electrical system.

I'm at my witts end here. I'm gonna try a new alternator and see what that does.

Do these ammeters go bad? I'm pretty sure the ammeter is a very simple mechanical coil or metal loop that just physically moves a needle. I dont think they go bad unless they get shorted out. My ammeter returns to middle of gauge when the car is off which is what it's supposed to do

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Voltage drop is a better test, you are correct. Ohms test works in MOST test, however, if you have multi strand wire, it can pass ohms but not handle current

At this point, what about running jumpers to everything charging related? I'd be curious if it still acts up. If it doesn't, take each jumper off and hook up the stock wire till it acts up

As far as ammeter, they can to the point they can't handle the current, and really can cook the wires. I believe you drop tested AND bypassed?

You definitely have a crazy one here

I have a new alternator from napa. It's there "pro series electrical" whatever that means. description says it's 60 amps w/ single pulley. Hopefully that does something.

I identified a voltage drop of 0.6 from battery positive to the "IGN" terminal on voltage regulator. So there is something causing a a voltage drop somewhere in the ignition circuit.... It's not that significant of a voltage drop so I dont think it's the primary cause of my symptoms but maybe. Already replaced ignition switch... still no change.
Checked the resistance of ballast resistor and it was 0.6 ohms which is within specs as per my service manual.... But when I run a jumper from battery directly to IGN terminal on regulator nothing seems to change either. I'm gonna look more into that.

I would really prefer not to open up the "in harness splice" since I vaguely remember fixing it when the harness was on the work bench but may have to if this new alternator doesn't fix things and wiring checks out. I definately remember that splice when I opened it up. I even have a memory of re- soldering it and cleaning it up. I'm pretty sure I checked resitance on the whole dash harness at that time as well. It was almost a year ago and with so much other stuff going on I cant recall exactly what it looked like or what I did.

The only thing left other than the "in harness splice" to check is the 5 prong block connector that goes into the igntion switch. And I think that's really it... the bulkhead connection has just been redone with new connectors and no reason the connections should not be good.

Just to state again my problems are
- IDLE drops to much when I put into gear (was told by a member here it should only drop about 50 rpm when put into gear. Mine easily drops 150- 200 rpms when I put into gear..
- flickering lights and unsteady ammeter that also ticks sometimes and makes a very faint "doink" sound
- sometimes it wants to die out or stumble when its idling in gear and problem used to always get worse if the car was really warm after driving for a while. Other than that it drives fine.

bearman said:

You have a stator getting hot and causing a short in the alt. Start the engine then take the main feed wire off the alt and cover it up so it doesn't hit anything then go drive it and see if the problem is gone.

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IMO...
NEVER disconnect the output wire from the alternator while its running or the alternator will be damaged. The alternator must be connected to a load (cars battery and accessories) or the diodes will be or possibly be damaged due to excessive voltage.
The stator windings if shorted to ground will be manifested as burn or arc marks to the case if the slot insulation is faulty. Bear in mind that that there is a common stator windings connection that is UN-grounded. The output connection of EACH of the stator windings get connected to the junction of one of the positive and negative diode junctions. All negative diodes have the anode connection grounded and all positive diode cathode connections are grouped together as the output of alternator. This is how the three phase full wave bridge rectifier circuit is designed.
Have you checked the rotor connections and windings for short circuit to ground and continuity? IF there is a loose or intermittent connection in the rotor, which can be effected by rotor RPMs, this would account for erratic voltage AND current output which varies with engine speed. Just my opinion of course.
BOB RENTON

Well I disconnected the 4 wires going to the wiper motor. It was two block connectors with 2 wires each. When I disconnected one of the block connectors the wipers turned on... then when I disconnected the other block connector I saw a small spark like some kind of short

Anyway the ammeter fluctuation seems to be gone now. Cant tell quite yet if the other symptoms are fully resolved

Evan Frucht said:

Well I disconnected the 4 wires going to the wiper motor. It was two block connectors with 2 wires each. When I disconnected one of the block connectors the wipers turned on... then when I disconnected the other block connector I saw a small spark like some kind of short

Anyway the ammeter fluctuation seems to be gone now. Cant tell quite yet if the other symptoms are fully resolved

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Interesting, I wonder if it was drawing the power, but if you ran separate wires ( I think you did) to the alternater and voltage regulator, that shouldn't have affected the problem, as long as you took the original wiring all out of the equation

Im very interested if this is the final fix

Someone mentioned to try to disconnect wiper switch earlier, thank you. I'm not sure why I didnt get around to that until now. My wipers always did act funny.

Yes the ammeter fluctuation and tick with faint "doink" sound is completely gone now when the ignition switch is on. It still bounces a little bit with car running at idle, then steadies out when the RPMS rise.... which is less concerning that what it was doing before..

Also I'm not sure exactly what I did but the voltage drop I was getting from battery to ING side of regulator has now dropped from ~0.7 to 0.4 so I'm thinking that is all good.

Looking at the wiring diagram it seems the ignition switch does in fact feed the wiper switch so maybe that's why the meter would act funny and tick with ignition switch turned on (didnt matter if engine was off OR running) ... it was just easier to notice the sound especially with the car off. Something was going on and disconnecting the wiper motor fixed it. I'm going to remove wiper motor and switch to try and isolate the problem further since I wouldn't mind having wipers.

I will put on this new alternator and see if that steadies out the ammeter even more when I'm at idle

Iirc, in my 67, there is a circuit breaker within the wiper switch and power for the reverse lights goes thru that switch.
The switch also grounds to the dash just by it being held on in the front by a nut on the plastic dash bezel.

Just throwing that out there, some strange factory wiring.

New alternator doesnt seem to change much but my charging mysteries seemed to be solved for now.

Still trying to fix the low idle when I put into drive. It drops about 200 rpms and starts to run bad. In neutral it's fine. I may start another thread for that.

Glad the wiper motor fixed your problem.
As far as the poor idle goes, a couple questions:
1. Have you done a recent compression test?
2. Carb is clean, particularly primary idle passages?
2.a Mixture screws are set properly.
3. No vacuum leaks?