Alt Gauge Question C3

[Thomas Christopher]

My alt gauge is jumping around when I do anything. Turn on the turn signals, and it jumps, hit the brakes and it jumps, turn on the headlamps and it runs at about 1/2 in the negative area. I checked my voltage with the car running, and I'm getting a solid 14+ at the battery. What would cause my gauge to jump around like that.

And while we're at it, what's the chance of finding a 69 or 70 alternator? My 69 is a very late run, and the judging manual says that 70 alts were used sporatically through the late 69 run.

350/350, 4sp convertible

Thanks in advance

[Mike Cobine]

Re: Alt Gauge Question C3

Two possiblities:

1. You do not have a high current connection back to the battery from the alternator. There may be a feed via a 18 ga wire somewhere that is keeping the battery charged, but it won't let the battery handle the load when devices come on or go off.

It could be simply a connection that corroded.

2. Often there is a condenser on the back of the alternator to prevent wild fluctuations like this, so that it moves slowly and doesn't alarm the driver. Check that you have all of yours against the wiring diagram in the AIM.