Finishing up Covid refresh of my father-in-law's 68 442. I had the original alternator restored and replaced the external voltage regulator with a new AC Delco one. Last couple start ups I noted the "Gen" light infrequently come on through different RMP ranges....usually 1000-2000 RPM, produce a kind of wining noise, then turn off.

I checked the battery which has been sitting around 12.8-13 volts. I tightened the alternator belt so there is no slippage. When the car is started I check the battery and noted there is 14.5 to 15 volts going to battery. Last night after about 3 minutes voltage dropped to low twelves.

During my first test drive of the vehicle last week Sunday "GEN" light was coming on periodically and making a kind of whining noise when it did. After driving it for 10-12 minutes then restarting it the battery was weak (using a vacuum pump for master brakes power booster that runs periodically). Last night I retightened the ground wires to the motor and and from the battery to front of the car near headlight connection (looked little loose). The wiring is definitely old and coating seem brittle in some spots.

Wondering if anyone has seen this or thinks this could be from loose ground or maybe bad voltage regulator?? Is there anything I can test with the external voltage regular short of buying a new one (shot old one away already F!!!!).

Thank you,
Chad

 

Put the old regulator back in and see what happens.

 

Also make sure there is a star washer on one of the mounting screws, between the regulator body and the firewall. The regulator needs to be well grounded.

 

copy that....behind one of the three bolt that attach it to the firewall?

 

Yes.