If its only at idle you may be set too low, you need preferrably 800rpm for a stock alternator to put out a constant.
If its at cruising I'd lean more towards the voltage regulator or loose belt or even an alt brg just starting to seize.
First thing I would do is the simple thing: check your belt (no more than 1/4 to 1/2 inch up/down movement. Next would be to have your alternator checked/test for output(underload) and wear from an alternator rebuild shop, not your local yahoo's outlet that have students learning and doing system checks.
If above checks out ok, I wld then check all the gounds (and I mean ALL). I'd also check the feeds to your horn relay and its ground as well.
Start there for now & let us know what comes of it.
It sure is a pain doing an electrical prob trace on these old girls with wiring over 30yrs old, but you'll find it. Just trace your grounds systematically so you don't miss anything.
If the lights are "pulsating" at a steady rate, it's your mechanical regulator cycling. If they are "flickering" (there is a difference!), then look for a bad ground or a bad connection on the horn relay, although bad grounds or corroded connections in this circuit usually show up when trying to start the car because of the fairly large current draw. An easy way to find out is just replace the regulator with a Wells solid state unit from Auto Zone. For under 10 bucks, it's a cheap fix AND a direct plug-in!
My car did this for a long time because I didnt notice it other than idle (I figured that it was idleing too low) but my dad saw me coming down the road and said it was doing it. I put on a different regulator and it changed nothing, put on a new rebuilt alt and its all gone. Just a little more info for ya
1970 Chevelle Malibu dark blue 350/TH350
~Big blocks make your Heartbeat faster. Too bad I dont have one.... oh wait, yes I do!!!
~"We always take my car cus' its never been beat, and we never missed yet with the girls we meet, I get around!!" Beach Boys
The original type voltage regulator uses mechanical contacts, or relay type coils, if you will, to regulate the output of the alternator. The Wells unit I spoke about is a solid state unit with no moving parts. The pulsating you are seeing is actually the "relay contacts" opening and closing causing the voltage to actually oscillate up and down. If you measure across the battery terminals with a VOM, you'll see the pulsations in the meter deflection. Try to find the Wells regulator, model VR715, under 10 bucks. It's the cheapest AND easiest thing to change before you go for another alternator.
Thanks everyone, I bought the Wells VR715 today. I was sitting around thinking about this and I apologize for not mentioning it, but last summer I installed a MSD distributor, coil, 6A ignit. box, and a Holley elec. fuel pump. I believe this is when my pulsating lights started. I read about the cs alt. conversion. This should my next step right? I have one of those autozone alt in there now(stop laughing). Thanks again
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