I just put in the Rallye Pac in my 72 Cutlass Supreme. All gauges work well. This was after two oil switches and two temp sensors later. I also got the tach to settle down by putting on new plugs, wires, new distributor points, new distributor condensor, new distributor cap, and new ignition coil. I also went with a VR715 Wells solid state volt regulator too. With this said, I have a light humming sound coming from the dash. Any ideas? I am concerned there is some resistance going on. Battery and alt are good, battery is at 14.3 volts with car running. Battery checks out at around 13.8 with car off. Alternator is 61 amp, and brand new. Any help is much appreciated.

 

I moved your post to its own thread to get you some views.
Can it be heard in ACC or IGN positions or both or off?
How loud is it?
Is the fan, radio or tape player on?
Sounds like the charging system is working...

 

Rob,

Thanks for the reply. It is not humming in the ACC or IGN positions. Also, radio and AC/Fans are off. I have a 1a inline fuse in the tach line. It came with a .5a fuse, but thought that was a bit worthless. The braided wire is grounded to the metal part of the dash where the gauges go. It seems the humming is originating from the tic tock tach, though. Did not notice the humming prior to installation of the Rallye Pac. However, when I did the distributor points, I noticed the static shield was not present. Don't know if this could be the issue.

 

It's the clock motor most likely.

 

Pull the clock/lighter/courtesy light fuse and see if it goes away.
The repro rally pac clock should only give a tic tic sound but not sure what an original clock would sound like.
The lack of braid grounding would not cause it.
Very odd!

 

I think I may have found the problem. The hole for the screw that grounds the Tic-Tock-Tach gauge to the dash is stripped. I was able to make the faint humming sound go away when I pushed the gauge in tight to make connection with the metal ground on the dash. I have to get a bigger screw for that stripped hole to make sure the connection stays tight. Since buying a 39 year old car, I have learned to respect plastic parts and handle them with care. Otherwise, it can get costly! Thanks for the help and I will report back this evening on the fix.

 

Sorry for the late reply. Been busy with work/travel. I was able to replace the screws that hold the tach housing to the instrument panel. The tach is now well grounded to the metal tab on the panel. Still getting a faint humming sound from the tach. When I press on the tach housing, I am able to get the humming to stop. At this point, I am at least satisfied that the humming is not a major electrical resistance issue coming from the Red Batt wire going to the clock. I may be picking up static from the distributor through the tach wire though. Any last thoughts?