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When my car is running the ammeter bounces around across the guage. I’m assuming the voltage regulator may be the problem as I’ve ruled out loose grounds and bad wiring. Is there a simple test to confirm this before I install another regulator?
 

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The 66 ammeter is known for being an unreliable design from the factory, few actually work, others have evidence of burning on inspection, and some have been converted to voltmeter duty. If yours worked before, and the charge is steady at the back of the alternator, the regulator would be a good place to look.
 

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The 66 ammeter is known for being an unreliable design from the factory, few actually work, others have evidence of burning on inspection, and some have been converted to voltmeter duty. If yours worked before, and the charge is steady at the back of the alternator, the regulator would be a good place to look.
The "AMP" gauge is not connected in any way to the CVR on the back of the instruments.

I'd be thrilled if any 66-73 AMP gauge "bounces around". Usually they just lay there.
 

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The "AMP" gauge is not connected in any way to the CVR on the back of the instruments.

I'd be thrilled if any 66-73 AMP gauge "bounces around". Usually they just lay there.
Yeah I actually meant the main voltage regulator on the radiator support, if the alternator is doing what it's supposed to. The gauge itself is probably what's shot.
 

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Try and associate why it might be moving like something going on or off. If not i would suspect the wiring first, loose nut on back of it.
Ive had 3 early cars, only 1 the AMP gauge ever moved. it would move with anything, the radio, headlights, brakes lights and it would flutter and keep time with the turn signals.
 

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My factory ammeter never worked and when I installed a Voltmeter in it's place, I had a constant "flutter" in the needle. I traced it to an inadequate ground from the engine to the body. After adding an additional cable from the engine ground lug to the chassis/sub frame, the fluctuation disappeared.
 

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The 66 ammeter is known for being an unreliable design from the factory, few actually work, others have evidence of burning on inspection, and some have been converted to voltmeter duty.. . . . . .
My ammeter. . . .
741836
 
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