I need a little Help

[Big G 74]

Fellow Mopar Enthusiasts,

My alternator is not charging. Just redid the wiring harness and everything works fine, except the alternator. when I check the battery, it show 12.25 volts when its running, where it should be jumping up to 13.5 ish, correct? So, I replaced the new alternator with the old one, which I know works, same problem. I tried a new voltage regulator, same problem. I am running a MSD ready-to run distributor on a stroked 440, no ac, just motor. I had a mechanic friend of mine check the wiring and it is solid, not the issue, everything is correct, so I am at a loss. So, does anyone have any ideas of why it's not charging. Anything would be appreciated.

thanks

Big G 74

 

[dryheat]

Are you checking it at idle only? Try increasing the RPM and see if that makes any difference. Also ... double check all of your grounds.

 

[WP29440SE]

charging volts should be 13.8 - 14.2 . a new alternator does not necessarily mean its "good" . the charging system heavily relies on grounds. the VR must be metal on metal with the firewall, that is its ground. in turn , the battery to block to body grounds must be SOLID. make sure your clamps are good, battery posts are clean etc etc .

here is more information

http://classicmopars.proboards.com/index.cgi?board=electricalt

under charging system diagrams

 

[67 coronet]

take the pulled alt and have it bench tested to start with.al least that will solve that question.as said earlyer,bad grounds are the most common problem.

 

[451Mopar]

What alternator/regulator setup or year vehicle?
The older alternator with mechanical regulator regulated output by pulsing the +12volts to the alternator field. This is usually refered to a single field terminal alternator because the other end of the field wire is connected to ground at/or in the alternator.
The newer alternator with electronic regulator uses an alternator with two field terminals. One should have constant +12 volts with key on power, the other connects to the regulator and the regulator controls the alternator field current through the ground side.
With either system, the regulator needs to have a good ground connection.
You can test the alternator by applying +12 volts to the field wire terminal, and on the newer alternator, also grounding the other field terminal. If the alternator is good it will be putting out maximum current at the RPM it is turning. If you check the alternator output at the output stud and it is higher than at the battery, you have a connection issue between the alternator output and battery. If that check out, reconnect the voltage regulators and stock wiring, and make sure the regulator is getting +12 volts with the key on. On the old system you should see some voltage at the regulator output and to the alternator field terminal, if not check the wiring between the alternator and regulator.
On the newer system, disconnect the regulator connector. with the key on you should have +12 volts power on both terminals. If you measure voltage at the alternator field going to the regulator, it should be +12 volts with the disconnected regulator. When you plug in the regulator connector the voltage should drop showing that the regularor is controlling the ground side current.