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Problem is on a 68 Chevelle. When the car is idling, the voltmeter jumps quickly between 14-15 volts. Measures constant 14 at battery. However, the dome light, headlights, any light for that matter flickers at idle. The lights don't flicker on and off, just a small change in intensity. Also, the turn signals are blinking at about MACH 2.

Alternator tests good, new voltage regulator, no change. Grounding problem somewhere? Not familiar with how car was wired, bought in this condition. Has vintage a/c installed. Volts drop a lot on the meter with a/c on, not convinced meter in car is accurate.

Any help would be greatly appreciated
 

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Think I’d start out by looking at the voltage at the back of the alternator. Check the large stud with a meter to see what the alternator is doing.

The slight flickering at idle is caused by the regulator. What you are seeing is the mechanical regulator switching and it’s more pronounced at lower engine RPMs. The best way to eliminate the flickering is to go to an electronic regulator, either external or internal.

The alternators, in older cars, were not very big. In later years, GM increased the size to about 94 amps in A/C cars. Older alternators, in my opinion, are too small to run A/C at idle.

First thing I’d try, with the flashers, is to change the flasher can. Since both sides are doing it, I don’t see it as a bulb problem. The can is under the dash between the column and the radio. Replace it with a cheap $3.00 one from the chain auto stores.
 

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It sounds like the regulator is maintaining fairly close under load. The readings are a little high. I run about 14.7 out of mine. You should get a more stabile output if you switch to an electronic regulator, either an external unit or an internal one. It switches faster than the mechanical unit and gets rid of the flicker effect.
I run a Wells #715 solid state regulator on my 64. It was around $11.00 at AutoZone. If you go that route, disconnect the battery before installing and be sure to provide a good ground to the case.
 
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