I've got a 350 with an AC Delco 321-161 ( 51 amp) alternator. I've noticed that sitting at a stop light, with my foot on the brake and the blicker on. My volt meter ticks back and forth from 10.5 to 11. When foot is off the brake and just cruising down the road, volts are at 12. I was under the impression that 14 volts should be flowing through the system?? Is there a problem here?

On a hot day, stopped at a light, with foot on the brake and electric fan going, volts are at 10.

The blinking voltmeter is pretty normal.
The low readings are not. you should have 14-15 volts, even at idle. Mine "Blinks" from 13 to 14.5 volts.

I'd start by verfying your voltage with a digital voltmeter. If you don't have one, you can get one at any home center or hardware store for $35.

Next thing I'd do if the voltage was verified as low would be to take apart every connector in the main power and charging system and clean the terminals, then test the voltage again.

If you have a mechanical regulator, there is an adjustment screw inside on one of the coils that will raise your voltage.

Also, 51 amps is pretty minimal for a car with an electric cooling fan.

The electric fan runs through a Hella 12V 40a relay.
Fan also runs after engine shuts off to continue to cool the motor. I've notices the velocity of the fan drops once the car is off too. Is that normal when running through a relay? What kind of alternator should I be running? What's a good "amp" put out?

How can I tell if I've got a mechanical regulator?
Sorry for all the questions

The mechanical reg is a square box, maybe 3" on a side, mounted on the drivers side rear of the rad support, with a 4 wire flat connector going into it. There are some pics in the "what it is where it is" sticky at the top of the electrical forum.

If the fan slows down when you shut the engine off (voltage going from 14v to 12 would do that) I'd guess the only thing wrong with your charging system is the guage isn't perfect. Again, a check with a good digital voltmeter would reveal much.

Unlike many, my own belief on "how many amps is enough" knida goes like this: If the car starts every time I turn the key, ie: the battery isn't running down, then I have enough amps.

51 is a weird number, r you sure it isn't 61? it would be stamped on the top of the alternator case, as in: 37A or 61A or something like that.

The electrical basics sticky in electrical makes some good reading if you want to enhance your knowledge of electrons and things.

Remember that relays are good for getting power to accessories, but they don't do anything about making power. If the alternator doesn't make enough power then it doesn't make enough power.
At idle it is rare for the stock alternators to keep up with any load.

I ran into this when running duel electric fans also. I was even running an 80 amp internal regulated alternator. Found out my problem was I installed a performace pulley system on the car which lowered my alternator rpm's just under getting maximun output. I either had to bump up my idle speed or finally what I did was reduce my alternator pulley size. Does your car still have the stock pulley's on it. It may just need a slight increase in idle speed to keep the field excited.

hmmmm ....
well I believe the problem is in the volt gage.
Used a voltmeter and everything checked out.
Car HOT and running ... fan blowing.. blickers on ... I've at 13.7 volts on the meter .... but GAGE shows 10.

It's one of the autometer gages .... does anyone know if these can be adjusted?

I don't know how to adjust it, but I'd recommend making sure you have good ground for it.

take your voltmeter into the car and check voltage at the back of the guage.

If you read 13.7 ish, the guage is bad.

10 means you have a bad connection or two, could be either the power or ground side. Split the difference by reading from the plus side of the gauge to a known good ground.

What circuit is the hot side of the guage connected to?

Look at it this way, it's lots better than a charging system problem.

Some of the aftermarket guages have a potentiometer inside the back - often only visable after removing the light bulb. OEM guages usually use a shunt resistor on the back of the guage to calibrate it. The shunt resistors looks like a piece of ceramic connected accross the two terminals.