voltage gauge bounces and lights flickering.

[74dusterman]

My car is a 74 Duster with a 360. I am having issues with the voltage gauge bouncing and the lights flickering. The engine bay has been completely rewired with all new wiring, all of the lights have been wired with relays, headlights are converted to H4 halogen, msd 6al box with blaster coil, and I have done the amp gauge to voltage gauge conversion. The voltage gauge bounces between 14-16 all the time, doesn't matter if headlights are on or off. I have tried everything I can think of from different alternators, new voltage regulators, ground straps from body to motor, motor to frame, body to frame, and even from voltage regulator to body to make sure it wasn't a bad ground. It is driving me crazy because the lights flicker rapidly like a strobe light. Has anyone had this issue or does anyone have any ideas?

 

[diymirage]

alternator belt slipping?

 

[67Dart273]

The main thing that causes this are things like bad connections / voltage drop in the harness as well as the ground side of things. Sounds like you may have fixed that part

Since you have already tried a lot of "stuff" I would next try the following. You can do this with minimal intrusion into the harness by doing the following

Get a "Bosch relay" and mounting socket, and an inline fuse. Not important, 10-20A or so

Get a spare VR connector pigtail, junkyard, etc. Ma used this fairly late, up to ?? MPEFI? or so

Disconnect your green field wire. Run a temp wire from the VR spare pigtail to the alternator field

Wire up the Relay. "Tap" into your switched "ignition run" to fire the relay. If you have a ballast resistor you can use that, and of course ground the other coil lead. Be sure to check for diodes in the relay by checking with your meter at the coil connections.

Wire the hot feed to the relay through an inline fuse to the starter relay terminal. Wire the load contact to your VR blue pigtail connector

See if you now have improvement!!!

Have you checked with a meter for ground problems? With engine running at fast idle / low cruise, make the following measurement with all load off, and again with loads turned on, headlights, heater, etc

With your meter on LOW DC volts, stab one probe onto the battery NEG post. Stab the remaining probe into the mounting flange of the VR. Be sure to stab through paint, rust, etc.

You are hoping for a very low reading, the lower the better, ZERO is perfect. More than .2V (2/10 of one volt) is too much and indicates a ground problem

 

[74dusterman]

New alternator belt and I have had it tight enough to play a tune on. Thanks for the suggestion though. Thanks 67dart273 also. I will try checking it with the meter first then I will try the relay and wiring like you suggested. I probably won't get time to work on it until the weekend.