While I have had only one minor issue with my 50 year old original external points style voltage regulator on my 68 Chevy II Nova. Turns out someone not knowing what they were doing adjusted it internally to where the headlights were VERY bright and it burned up the aftermarket radio as the voltage a lot of times was close to or a little over 18V when the motor was running. Once I adjusted the regulator, it has performed very well over the last few years since the adjustment.
I found it interesting that it's been said that the stock point regulator alternators have headlights flickering up and down, and up and down and I never noticed this on my car so I decided to do some tests.
Below is the video I took the other day on my 1968 Chevy II Nova with the original 50 year old external voltage points regulator and the 50 year old 37A alternator, as well as it's original 50 year old wiring except for the main battery cables. I also have installed reproduction T3 headlights that when I tested them years ago produced 65.5 watts with a 13.4V input while originals I had and did not put in with the same input voltage only had 48 watts.
And here is a chart of my results from the video:
I can see from my chart from the test that the voltage does vary but I'll comment on what I see.
When the car was started and running, the voltage was on average 13.7V between the times of 1:45 and 1:49 and while the voltage between these 4 seconds varied 0.02V, I REALLY doubt this would affect anything major.
If you then look at the time of 1:50 the voltage did sag going down to 13.41 due to the load of the headlights high beams as well as the additional load from the parking lights being added to the electrical system.
At 1:51, or one second later the voltage was increased to 13.57V coming up from the lower 13.41V abd then at time 1:52 the voltage went to 14.04V and then a second later went up an additional 0.02V to 14.06V
Now with the load of the headlights being on high beams as well as the parking lights being on, the voltage DID eventually drop to 13.87V but it was after 30 seconds and I NEVER measured no peaks or dips that would then allow me to see flickering in the headlights output.
As far as anyone saying that once the point style regulator is replaced with a solid state style that this will stop the oscillating of light intesity up and down, this could be true and I have not changed out my old style points regulator to see how much of a change would occur with an electronic regulator. My original points regulator is only allowing on the one test a variance of a high of 14.06V down to a voltage of 13.87V over the time of 30 seconds. The whopping fluctuation was 0.19V and to me this very small variance of voltage over 30 seconds and will not have my headlights flickering. Granted the headlights will be dimmer with a lower 0.19V but while I have not done the math, if it reduced the headlight output by let's say 2 watts and the headlights at the higher wattage are putting out 65 watts, then the change to me between 65 watts down to 63 watts I will never see. Double this up since I'm running two headlights and now if the wattage went from 130 watts down to 125 watts, I probably will never see this difference. It's just not any type of large change.
Another observation of my chart from the test is when the car is running the points system is supplied with a battery voltage of 13.71V to 13.69V and then once the headlights and parking lights are turned on the battery voltage increases to 14.06V to 13.87V which to me is good as now the headlights instead of possibly getting 13.69V, they are getting a higher voltage and the charging system is doing what it should with providing the additional power for these things.
A last observation of the chart does show a dip when the headlights and parking lights are first turned on and this is due to the delay of the voltage regulator sensing this additional load but then as quickly as it can, it brings the voltage back up.
I'm not wanting to start any arguments but to provide some good information but one also has to look at what happens when a voltage regulator get's changed. We remove a connector on the old points regulator and then plug it into a new one and when this happens better or worse connections can occur from this action. Could this weigh in on the results ?. Yes it can just like I have unplugged headlight connectors and put them back on only to have sometimes the headlights become brighter, or stay as how they were or be dimmer or not functioning at all. The old style points style regulators also have contact points inside that after cleaning and adjustment can then start working better than how it was before or the performance could be worse.