Running at fast idle or above generator and battery voltage should be about 7.5 volts. You have a charging system problem. If the generator output is 3 volts it's time for a rebuild.

Hi Bruce

Tiny is right, you have a charging system problem.

But you haven't told us what you are running.

Is your charging system a 3rd brush system, or do you have a voltage regulator?

@ole-olson 

it has a voltage regulator.

@bruce-bernhjelm 

Okay

The first thing I'd do is connect your volt meter between the armature terminal of the generator and a good ground, run the engine at a fast idle, and MOMENTARILY ground the generator field terminal.

The generator should charge at least 7.5 volts with the fields grounded.

If it does, you have a problem with something other than the generator, probably the voltage regulator.

If it doesn't, you have a generator problem.

PS

Probably the FIRST thing to do is make sure the generator is polarized.

With the engine off, use a jumper wire to spark across between the BAT terminal and the ARM terminal on the voltage regulator.

It only takes a little spark.

@ole-olson 

thanks Ole, 

I now have 6.9v at the generator,

6.5v at the battery with the car running

and 6.23 at the battery with nothing on. 

@tiny 

thanks Tiny,

I now have 6.9v at the generator,

6.5v at the battery with the car running

and 6.23 at the battery with nothing on. 

That's better but the generator should be closer to 7.5 volts output at fast idle and up. Are your measurements at idle or fast idle? If at idle bump it up to a fast idle and check again.

@bruce-bernhjelm What happens when you are fully dressed? Couldn't pass an opportunity to comment on a literal interpretation.  A fully charged 6 volt battery should be 6.4+ volts.

@tiny today I checked and is is 7.1 volts at 2300 rpm’s. The car seems to run fine. 
I turn it off and it won’t restart.

Check all the connections to the battery and between battery and starter. Likely there is corrosion or dirty connection that reduces the power to the starter. If all that is determined to be okay take the battery to a local part supplier for a battery load test.

@tiny thanks tiny it was the timing.

@chip thanks Chip it was the timing.

Thanks ole it was the timing

We need to remember to ask the question Is the starter speed slower than normal? If we don't then we fall into the slow starter assumption.