Hello everyone,

I have a 1965 barracuda with a 340. last year I had the motor rebuilt and at the same time I changed to electronic ignition and switched to the newer style charging system with electronic voltage regulator and squareback dual field alternator. At the beginning of the summer the car wouldn't charge so I did some trouble shooting and found out it was the alternator. it was still under warranty so it was rebuilt and reinstalled. worked fine for a week and then stopped working. I trouble shooted again and a diode was missing from the inside of the alternator I figured they were just crappy rebuilds so I bought a new one from another supplier. while waiting for the new one I checked the wires to eliminate a wiring issue. passed a new green wire from VR to alternator, a new blue wire from ignition source to alternator and ensured that the VR was well grounded.

Now I installed the new alternator, verified its charge at idle (14.2V) and with higher RPM (wouldn't pass 14.6V). Assuming everything was okay I started to drive the car and after about 2 weeks the cars not charging again...

I verified I had my 12V ignition at one of the field terminals and when I unplug the green field terminal I have my 12V there as well so my field isn't open. Bypassing the VR and bringing a straight wire from ground the the Green field terminal to test max field output there is still no charge so I can eliminate the VR being the problem right now.

Does anyone have any idea what could keep frying my alternators?

 

With our old systems I would look at possibly the amp gauge or feed thru the firewall

 

I would add... Make sure the following grounds are in good order.
Engine to Frame
Frame to Body. I like to add an extra ground from the VR bolt to the engine just for good measure.

 

I already added a 0gauge wire from engine to frame. I think I'll add an extra ground to VR to make sure