Starting problem......sometimes dead!

[northerngmc]

I am having, what seems to be an intermittent starting problem with my 69 GMC.

Truck is a 1969 GMC halfton, 305 from the late 70's, 3 speed manual. The truck has HEI, and an alternator with the external regulator elminated.

The problem is it will start regularly and cranks just fine. They all of a sudden, nothing, I turn the key and absolutely nothing. It happened last weekend. I had been out at my wood lot cutting trees and then stopped on the way home for gas. Put $35 in the truck and then it was dead. Radio would work but it would not even turn. Seemed funny to me that it would go from starting and cranking fine to nothing. I called my wife and she ran over with the car and booster cables. Started fine with the boost. I drove home 5 blocks and shut the truck off, the it started right back up again.

I drove the truck on and off all week without incident again until this afternoon. Same thing, I had spent the morning in the wood lot and then came home for lunch. After lunch went out to start the truck and nothing.

So I grabbed my volt meter. Battery was reading 12.6 volts. I checked my cables and they both looked clean but a little loose. So I tightened them both up, then boosted it to get it going. When running the volt meter shows just over 13 volts and now I shut the truck off it is showing 12.7 volts and will start.

I hooked my battery charger on and it went right over to 6 amps.

One more piece of information, I had the starter rebuilt last summer.

Questions....

1) How many volts should a fully charged battery show?

2) How many volts should it show when it is running if the alternator is working properly?

3) Why would it go from starting to nothing? It seems like when the voltage drops below a certain point everything stops.

4) What should the charge meter in the gauges show? Mine sits in the middle no matter what? Could it be out of the curcuit with the internally regulated alternator?