Strange Electical problem

[3lotus]

My lovely '69 +2 has a funny quirk. The only mod is an alternator which I was reluctant to do, but.. it seemed too weak to do everything.
If I've been on a long drive with the lights on when I come to a stop the AMP gauge will swing to the "-" side and things a bit dim a bit . If I put on the brakes light and use the signals the headlights will go out as the signals blink on. At the beginning of these drives the Amp gauge will be on the plus side or in the middle. Sometimes when we start out it will be on the neg side and then just snap over to the positive side , way over.
It seems to pretty much do the same thing with either a Generator or Alt.
So I feel like I'm missing something
Thanks, Paul

[stugilmour]

... If I put on the brakes light and use the signals the headlights will go out as the signals blink on.....
Thanks, Paul

This sounds like a flakey ground on the front side lights and headlights. Any time anything like this happens, nine out of ten it is within the grounding.

I believe in stock configuration both of these are handled by the front ground, so this should be checked & cleaned thoroughly.

I had a similar problem at one point, and it was a bit of a less likely ground fault. Check both grounds on the front side lights on the actual light housing. They are on a solder-on smooth brass bullet connector that fits into a ring clip affair on the housing. They can loosen and / or corrode a bit. This was my problem. The easiest way to check the front side lights is to unscrew the whole housing so you can see what is going on. Squeeze the clip ring with pliers after cleaning to make sure the connection is firm; mine fell off again when I was re-installing.

The same ground arrangement is present on the rear light assemblies, which also may be bad if the brake lights are causing issues as well. You may be able to inspect them by lifting up the panel covering the rear of the boot. If you need to remove the housings, be careful not to strip the phillips head mounting screws or break them off; mine were very frozen from corrosion and some broke.

What seems to happen is the ground being disconnected puts potential back to the ground of the other circuits (head lights, side lights, etc.).

I doubt this is the same fault as you are experiencing with the charging system, but should perhaps be remedied first.

To get help with the charging issue, suggest you clarify type of alternator used and whether it has it's own internal voltage regulator or whether it uses the stock regulator,

HTH