This is on 68 Chevelle 350 with headers. I'm getting an intermittent alt light on the dash. When I rev the engine it goes away sometimes. The tester at two different stores indicates that alternator is not sending enough amps to the battery. With the engine running and the tester hooked up I twisted the alternator wire that runs along the radiator support over to the battery terminal block with no changes in the readings.
I have bench checked two different alternators and both tested good. I have slaved in three voltage regulators. Have bench tested and tested in the car two batteries-both tested good. All wires at the battery and the alternator are tight.

Any thoughts on why I'm having battery charging problems? What other test can I do to isolate the problem?

Well, that's a lot of swapping so I'm not going to suggest that.
Is the regulator grounded. I forget which year they stopped using the rubber well nuts to mount the regulator. It needs to be grounded.
When the light comes back on at idle measure:
Blue wire at alternator to ground. Should be around 13 volts.
White or light colored alternator wire to ground. Should see maybe 5 volts.
Red alternator wire to ground. Look for about 14 volts to ground.
My thoughts to see what may be happening.

How are you "bech testing" them?? If the parts store(I am assuming that it is a reputable parts store) is telling you that it is not sending enough amps to the battery, then my guess would a bad alternator.

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http://community.webshots.com/user/moabdad The reason for muscle cars & big trucks is for the power. Here is the theory I used: Power=Good

Like John said. When you say you "slaved" in three regulators, did you mount and ground them? They MUST be grounded to work properly. Just hanging on the wire loom won't get it done.

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Dave Bradley
www.corvetteforum.net/classics/d1_bradley (http://www.corvetteforum.net/classics/d1_bradley)
'69 SS396 ragtop
'33 3W Coupe
'65 Vette BB Roadster

Grounds, grounds, grounds - check your negative battery cable - it may have a loose or corroded connection or break etc. It might carry enough to crank, but have too much resistance for the relatively small charging current.
Do you have an engine to firewall ground strap? How about a negative batt cable to chassis? this would provide an alternative ground path if your neg. cable is bad.

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