Flickering Lights

Dana67Dart said

I re-read your first post.
Im rethinking about the pulley dia. At 1200 rpm the alt should not produce a flicker. Have you had your charging system checked for bad diodes? Auto parts stores should be able to test for free.

Also as asked is it a flicker or a pluse?

To me a flicker is rapid, a pulse is slow,

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Various changes in brightness and voltage can also be caused by various problems in alternators, not the least of which is intermittent caused by bad brushes, loose windings which are rattling around and shorting, or problems with diodes.

I had my share of problems such as that on the old 70RR. The pulley ratio crank-to alternator was about 4:1, which means that at 5G engine speed, the alternator is trying to turn at 20K. I rattled two of them literally apart. One of them, the stator frame pins wore little notches in the lands in the case, and the rotor would contact/ rub on the stator. Yeh. I used to run the hell outta that thing

With 3.54 gear and the tires I ran, it was turning 3K at 70