When I'm driving my voltage reads around 14v, but when at idle it dips to 12v and when I put on my turn signal it will drop 2v and come back up with each blink. Is this an engine grounding problem, or a charging system problem, or something else? Any suggestions on where and what to look for would be helpful. http://forums.performanceyears.com/g...n_confused.gif

It's a '67 tempest with a 400.

When I'm driving my voltage reads around 14v, but when at idle it dips to 12v and when I put on my turn signal it will drop 2v and come back up with each blink. Is this an engine grounding problem, or a charging system problem, or something else? Any suggestions on where and what to look for would be helpful. http://forums.performanceyears.com/g...n_confused.gif

It's a '67 tempest with a 400.

You probably have two issues here. If your voltmeter is connected to your under-dash wiring, you are not actually measuring your battery (charging ) voltage. When your internal loads go up (directionals, etc.) you will see a voltage reduction in your dash wiring. This will also be compounded with poor grounding.

If your charging voltage drops when slowing to idle, either your total load is too high for the amount of current your alternator can produce at idle speeds, your belt is slipping, or your alternator is below its cut-in RPM, (the shaft speed where the alternator produces a voltage higher than battery). A smaller pulley on the alternator will help with the last issue.

Regards, Georg

I just replaced the alternator with a "stock" type 62amp unit. I was thinking of getting a heavy duty single wire unit soon. I think they are 100 or so amps. The headlights dim at stoplights and come back up again when coming off idle. I thought perhaps the alternator wasn't working correctly.

The votmeter is connected to the dash harness. Should I direct wire it to the battery posts?

As mentioned before, connecting to the dash harness will read slightly lower voltage. Insure all your grounds from the dash are in good shape; connecting directly to the battery will cause a slight current drain even when the key is off. A possibility may be to connect the voltmeter wire to the idiot light terminal (#4 on a mechanical voltage regulator, term #1 on a internally regulated alternator). This point has zero volts with key off and system voltage with key on, engine running.
Factory setups don't worry about precision readings since factory units are not really well calibrated anyway, and the gauge only gives a coarse reading. To accurately check charging voltage, use a good digital multimeter at the battery.

Regards, Georg