Why do lights dim off and on?

May have something to do with old wiring with new wired alternator . A simple design is 2 wires , the voltage is read at the source while in a better design the voltage is read at the end of any circuits getting a more accurate reading , also check for proper grounds and motor to chassis grounds , one wire has to provide an initial voltage for the " exciter " in the regulator to even work aside from the heavy batt. wire ., That's as good as I can explain it with the knowledge I have . U-TOOB has videos that could help you understand the basics of these systems giving you a better idea of what the problem may be .

I could have sworn I posted something yesterday , I think you need to get an understanding of how the charging system works , U-TOOB has videos on it , Perhaps you're mixing old and new technology and it's not working . ie. 2 wire alt system with a 3 wire alt.

The following is from my 1967 Chevrolet Factory Shop Manual. I would make sure you have the correct alternator (Delcotron) and voltage regulator to begin with. The transistor voltage regulator was optional and almost nobody ordered it. The alternator should have a square connector on the back of it. Not a rectangular connector on the top. The rectangular connector is for newer GMs with an internal voltage regulator and is wrong for your vehicle! Hope these pictures help!! Jim

Diagram from the 67 Shop Manual

Another

Voltage regulator showing connections

I dropped my timing from 10 to 8 degrees and i retuned my carburetor to adjust to the new timing and so far no clicking and lights stay solid. Im going to wait about a week and update my status.

That's interesting! I don't know what one would have to do with the other. Maybe a grounding issue? Thanks for the update! Please keep us posted!! Jim

Yes doesnt make any sense. Ive struggling with this for two years. Ive bought two different alternators with two different amps, two voltage regulators and a new wire harness. Ive done different combinations and nothing changed. Right now im using my original harness the alternator with the lower amp. It sounds weird on the highway but i think im just not use to the new setting. Drives fine but i will give an update later.

So far this is where im at. Lights still dim off and on when the the car starts on a cold engine but not as bad as before the tuning. When engine warms up the lights get better but dimming is still visible. The dimming completely stop when im at a red light but continues when i step on the pedal. When the engine is hot the dimming stops but does dim once in a while. A few side notes like i mention before when the lights dim the voltage regulator clicks also when lights dim the RPMs drop which means the charge on my battery drops which also means the sound of my car goes high and low due to the idle speed rising and dropping. Does anybody have any clues of what this is?

Double check the wiring going to the starter, especially the positive battery cable. Make sure it's clean and tight at the starter. Years ago I had a 1970 Pontiac Catalina (same charging system) and for months the lights would flicker, get dim and bright, and the voltage regulator would chatter while all this was going on! I couldn't figure it out. Then one day the car was completely dead! I found the nut on the starter that holds the positive battery cable on had loosened up and created a bad connection! I tightened it down and I never had any more electrical problems with the car! Make sure the two ground straps, one on each head, are securely attached to the engine and the firewall. If your negative battery cable bolts to the frame, move it. Attach it to a convenient location on the engine. I did that on my Pontiac and a 66 Cadillac that I had years ago too. Hope that helps! Jim

The belts, grounding straps, positive and negative battery cable are new. I'll double check everything and give an update.

All of the wires seem good but do you think im gonna need a bigger belt??

I usually shop at autozone so if you can get me a part number or a cross reference number thatll be great

What engine do you have? Air conditioning? Power steering? California Emissions (smog pump)? Jim

Its a 327 no A/C with power steering and no Cal emissions

The belt alignment is straight. It has all the correct brackets. I will check the fan and grounds but i thought the belt has to grip the pulley? Like the belt has to be above the grooves?

The one thing i do notice is when i rev my engine the belt squeaks and it never did that when i first bought it

I tried moving the fan and it does not move. I will checkthe grounds

The Napa part number for your belt is 25 7312. The belt should not squeal. Check your belt deflection midway between the two pulleys. It should be one half inch on a used belt. One quarter inch on a new belt. If you replace the belt, adjust it for the proper deflection then drive the car a few hundred miles and adjust the belt again. The second adjustment is often overlooked after a new belt is installed. Hope that helps! Jim

Im not sure if i mentioned this before but its not just the head lights that dim. Its also the dash, interior dome light and tail light that dim all at once.

Have you tried changing the voltage regulator again? You might have a defective one. Hope that helps! Jim

Yes. I still have the original one then i bought one a while back then i recently bought one but the reason why i bought another one was because i bought the first one from an unkown site. This new one is from classic industries. So im sure its not the regulator and its not the alternator. How many grounds should a car have in total?

I dont think ever seen a frame to engine ground. The engine harness is brand new so i know that ones good but i am using the original front head light harness. I will take a look at that. I will also send pictures of all my grounds.

Battery to engine

The small wire is battery to body

Engine to body on driver side

Engine to body on passenger side

Voltage regulator to body

Front head light harness to body and theres another ground on the other head light socket.

And alternator to engine. Thats all i have so that's a total of 8 grounds.

I found the problem. Its my light switch/dimming switch. You pull the nob out to turn on the lights and twist to dim the dash lights. When i twist it to a certain spot the dimming stops

That's amazing!! Glad you found the problem!! Thanks for letting us know too!! The good news is that headlight switch is still readily available! Jim

I was wrong its not the headlight switch.

I officially found the problem. Earlier in my posts i said that the dimming stopped when the engine was warmed up. It turns out that the electric choke was set a little too rich even though i had it set right in between lean and rich. So i leaned it out and the car warms up fast and doesnt dim. I never had a starting issue which made it hard to diagnose.