The problem is with a 305 computer controlled quadrajet. When the engine starts the voltage across the battery terminals read 12.8 to 13.2 volts. Did a quick check and removed the negative cable and the car continued to run and without the battery load the voltage on the cable ends read about 15.4 to 16. Reconnected the negative cable to the battery and slowly increased the rpms to about 2500. Voltage began to drop in a linear fashion to about 10.5 volts at which time I terminated the test. This is a junk yard "85" 305 I put into my stepsons "83" Monte Carlo after his old 305 threw a rod. Then engine runs really smooth, starts right up with just a pump or two on the accelarator and it holds right around 40 lbs of oil pressure. I checked the grounds from frame to block to body and they all give good continuity. It started last night when he called and told me the car died on him at an intersection. Brought my battery from the Formula down and it started right up. His battery only shows about 10.5 volts, it obviously has been getting slowly drained since he started driving it 2 weeks ago and the bout of subzero temps we've been having here in the Northeast hasn't helped. Oh yeah and there is good tension on the alt. belt so it isn't slipping. Anyone have any ideas as to the cause? Thanks for any replies in advance!

 

Have you had the alternator tested?

 

Yes I did Trickster. I had it checked at Advanceautoparts after we got the motor in the car just to verify that it was good. It tested good, but I wonder whether their test can determine how well an alternator will perform when under a real load such as when in a running vehicle.

 

I don't know about the store where you took it, but at the store where I work we can test the alternator on the car as well as on a machine in the store. If done right on the car it will test the alternator under load and show what the peak amperage is under load. being tested in the store it will only show voltage being produced and not amperage and it won't be under a load.