[bowtyebob]

The tachometer in my '64 (300HP 327) has become erratic since I replaced the speedometer. By erratic, I mean that it tracks RPM, but 'searches' and wavers and the needle can drop dramatically under moderate or hard acceleration. It worked just fine until I reinstalled it after reinstalling the instrument panel. I have gone so far as to replace the points, condenser and even the ignition coil. I'm almost out of ideas. Nothing so far helps.
Yes. I disconnected the battery while removing and reinstalling the instrument panel. I suspect either a damaged tach or a voltage problem. I'm wondering now if it could be with the voltage regulator (I'm rabbit hunting, I know) Should I repolarize the voltage regulator? ...or do I need a condenser on the coil ...or a new tach? Anyone have any ideas. Help!!!

 

[bowtyebob]

Nevermind

Turns out that wiring diagrams are a good thing. This may be of help to someone in the future.
It seems that if one wires the tach 'backwards' it will work, but not correctly. Make certain that the brown wire (12 volts) is connected to the terminal labeled "12 VOLT" on the cack side of the tachometer and the black and purple wire originating at the neg. side of the coil is connected to the terminal labed "TACH". Simple ...if you have a wiring diagram and a volt meter.