ammeter alternator?
 

hi all, i have a problem with my electrical system. my 1950 truck has a 350 motor and autobox with a 1 wire alternator fitted, there is another white wire attached to the connector on the alternator which i have no idea what it is.
the problem i have is when the motor is running, i get an intermittent whirring noise from the alternator and my ammeter needle goes from the 13/14v position to full, when the noise stops the needle comes back down to the correct position.
i assume the alternator has an internal regulator, there isn`t one anywhere in the engine bay and it has just the 1 wire connected. i recently had to replace the coil and module in my distributor, would this have caused them to fail?
any help would be appriciated as i am now worried to drive my truck any distance with the worry of breaking down.

bill.:confused:

Those alternators have one big wire going to the battery and a small wire which energizes when the key is turned to on. There is an internal regulator. Check all the wiring to and from the alternator for shorts or weak spots with frayed wires which could be causing a short.