Our cars did not come with a volt gauge, back then. They do on today’s cars – but not during the FMJ-body time frame.
The Ammeter detects a current draw – and for most applications – doesn’t give most people good data.
When car is at high idle, 14.4 volts is about right. The Voltage Regulator will charge according to the underhood temperature – for longer battery life (so charging voltage will be different when cold out (like say 30-) vs. hot out (110’, in the shade). Still, a voltage between 14 to 14.5 volts, at high idle, means the alternator is charging (voltage regulator is working, etc.).
At normal idle, 13+ volts is common.
The battery should between 12 to 13.2 volts when charged up (before cranking).
The starter quits working at roughly 9 volts and ignition will not work below 9.5 volts (but your mileage may vary).
Carbureted cars do have to have the throttle petal tapped (once) before cranking. That gives the engine a shot of gas plus resets the choke linkage. If you don’t tap the throttle – it will take longer for car to start up.
It is not uncommon for people to forget this important step.
There are not many things on our cars that can cause an engine off current drain.
Before starting: I would do this first (before diagnosing any electrical problem):
Find any underhood ground wire, remove its mounting bolt, take a wire brush and clean the dickens out of it, the bolt, as well as what it mounts to.
Common ground locations to clean, are the battery terminals (both), the large bolt on engine cylinder head (to negative cable), the ground strap on rear of engine to fire wall (which engine side can be fun to clean), as well as on (or close to) the core support (the chassis part radiator attaches too) there is a ground screw on both sides of car, for headlights and other electrical items. If you trace the small negative battery cable – it will lead you to one ground source. The other side will be in the same basic area.
The ground locations inside cabin or in trunk are not known to give that much trouble (but don’t rule them out).
The only things I can think of that would draw power when car is off (key in hand) are: dome lamp, glove box lamp, trunk lamp, head/park lights, hazard lights, clock (analog or digital) and radio station memory (and your car might not have all of these options).
Other components that have power when car is off (key in hand) would be: all of the lights mentioned above, stop lights, power door locks, cigar lighter, power antenna and source power for heated back glass (not for the control circuit, but power feed).
There are several ways to check if one of the above items is causing a problem.
The easiest one is "if you have a test light", is to disconnect the battery. Place the test light between the battery and battery terminal. If light is lit (but might be dim), then go to fuse panel and pull fuses for the above items, one at a time. The clock and dome light (if a door is open) will the test light to stay on. A person can pull clock fuse first and can push in the metal door ajar switch for testing purposes.
Process of elimination and taking your time will find your problem.
If test light does not light up, then you do not have a significant power draw.
Note: the test light test version works for our cars - but doesn't work on newer cars, very well.
BudW