High voltage output with new regulator 72 charger

[72 charger]

While trouble shooting backfire through the carb on my 72 charger with a 69 383 we check voltage off the battery and found it to be at 18 volts after the motor warms up. Had a new regulator when we found this out but bought a new one and installed anyways just to check same thing. Regulator is properly grounded to the fire wall on both mounting holes(paint scrapped etc) alternator is also new. Need advice on what could be the culprit. THanks

 

[70rr-brian]

If I had to guess I would say the alternator, while new, is pushing too much voltage out. The Alternator should have a wire that goes directly to the battery that the VR does not effect. Getting defective new/rebuilt parts is sadly all too common.

 

[mopwrd340]

The alt is putting out way to much should only be putting out no more than 14.5 while running replace the alternator before it cooks your battery.

 

[72 charger]

I know it is putting out too much but it is a new alternator as well as regulator etc. Is there anyway its not the alternator and something in the harness the harness was all messed up when we got the car and I was assuming it might be something in there.

 

[72 charger]

Being that the motor is a 69 cast date when we got parts we asked for parts that would fit a 69 dodge charger. The alternator we got is for a 69 charger is it possible that its not compatible with a 72 ignition system? We had to put a new brush on for a wire to fit on but thought nothing of it really but it just occurred to me that we may need a different alternator based on what has been said on this thread.

 

[70rr-brian]

You need a dual field (2 spade connectors) alternator to run electronic ignition. 1 field to the ballast the other to the VR. The screw on connection goes directly to the battery. As a matter of principle you should get a dual field alternator. Just go to any auto parts store and tell them you have a 72 charger and get a dual field alternator for it.

But the fact that the alternator has a direct connection to the battery is the key to your issue. The alternator is still putting out too much voltage. Grab a voltmeter. Put the red probe on the screw on contact on the alternator and ground the black probe. You should be reading high voltage there. Or rather the same voltage you are seeing at the battery. That is directly from the horses mouth.

 

[72 charger]

Got the issue resolved. Cars made in the 69 years used different voltage regulators than 72's, so the alternator we had was not compatible with the voltage regulator got an alternator for a 72 and works fine about 14.5 volts.