I take it you have an alternator that uses the external regulator. You canput a voltmeter on the battery terms or junction block. It should read at or close to 14 volts with the engine a little above idle. If its high you can remove the cover from the regulator. The voltage side is closest to the F term. See if the points are stuck. If it,s the original equipment Delco there is a screw by the base to adjust the voltage. If it is an aftermarket you have to bend the tab that the spring attaches to. Be very careful, one short or wrong move & puff of smoke it,s all over. After you foul it up you go buy a new one.
