Flickering or pulstating Headlights

Mattax said

Could be ripple voltage or a regulation issue.
Also possibly a poor connection or loose plate etc.

This is a good check.
Also, what is the voltage at idle? and is it steady?
How 'bout with lights on?


Yes and no.
You can see what the brushes in post 15: Alternator repair, a little show and tell.
In the photo below you can see where the brushes come through.
View attachment 1715319078
(The yellow arrow points to the output stud. If its loose it needs to be snugged up from the inside.)
The two copper rings on the rotor is what the brushes contact.
View attachment 1715319079

When electricty flows through the rotor windings, it creates a magnetic field. That's why the brush connections are called field terminals.

Click to expand...

Thanks for the link I read through your write-up, still not understanding fully what all the internal parts do so I'm gonna read my 1970 Plymouth FSM about it. I doubt the alternator is in that bad of shape it's only a few years old but it is a reman'd unit from O'Reillys. Also no the voltage is not steady at idle, it never has been... only when it's revved above 1300-1500ish RPM does it start to charge steadily (but the voltage still fluctuates). This is with the headlights off too.

This battery is toast btw I went yesterday to start the car and had to crank it a bunch to fill the carb back up after taking it apart, I couldn't have cranked it more than 15 seconds total before I heard the starter (which is a modern mini-starter even) slowing down and the voltage went well below 12 on the gauge which was too low for my Mallory ignition box to energize and fire up. Annoying!