VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 6 volt generator gone mad

On dads 28 Coupe that mom sold me,the generator starts out at 6 volts and continues up through 12 and 15 all at idie (before the smell of boiling acid waters my eyes and I'm forced to disconnect) This may explain the burnt out headlights of my youth and the burnt out wiring thats under the dash. My question is of the regulator. There is a small wire 14g or 16g thats on the regulator(condenser?) going to the unknown. Is the reg. wired to itself? And how will it control the generator? And the BIG question...whats wrong with it. Thanks

Hi Dad's 28,

Let's make sure we are talking the same unit of measurment. You are using the term "volts" which would require you to use a volt meter. Are you in fact talking about "amps" and are you reading the Amp meter on the dash?
:confused:

Let's assume you are in fact reading "volts". If this is the case, the most likely problem is in the generator which would require rebuilding.

If you are reading "amps" then the generator is probably okay and it could be a bad battery.

There is no 'regulator' on a 28 Chevrolet. The device mounted on top of the generator is a "cut-out" and operates as an automatic switch.

Hello Ray
I'ts volts and too many of them. When would the switch "cut out",at 8 volts? And the 28 is mostly original. Thanks Lowell

The cut-out is an "off-on" switch, and when the generator reaches a certain RPM (usually around 650 to 750RPM) the contacts close allowing the juice to go to the battery. When the generator speed is reduced to the point where the amp gauge shows a discharge of 2 or 3 amps, then the points open cutting the juice off to the battery. Since the cut-out is only an off-on switch, it has absolutely nothing to do with the amout of voltage the generator puts out. Due to the amount of voltage your generator is putting out, it sounds like your battery is not on line, via a bad ground. The battery has to be on line to act as a ballast for the generator. If it isn't, the generator will go nuts and put out very high voltage. Also, check your generator model number. For 1928 it should be a Delco-Remy model 943 B, and the output is controlled by the adjustable third brush inside of the generator.

Hi dads 28,

From what I understand now it is obvious that your generator is overcharging, based upon your measurment of voltage and the boiling and acid smell.

Upon ferther review of the "mad one", the lower mount is very loose and one of field coils has all of it's wrap burned off. So it looks like a rebuild and a remount is in my future for the 943 B. Also inside the armored cable at the generator I have two wires, one is for the amp meter and the second was taped. Does anyone have two wires or is this one of those "mysteries of old car rebuilding"?
I do have a aftermarket wire harness with only one wire for the generator. Thats why I'm stuck.
JD:How is the third brush is adjustable. Is it pressure on the armature or a adjustment in distance to or from an adjacent brush?

Hi dads 28,

Assuming you have the original wiring harness, one wire went to the battery by way of the amp meter. The second wire within that cable was the 'hot' wire that went to the horn that was located just beneath the generator and under the edge of the frame rail.

On the end of the generator is a screw that 'clamps' an internal ring which holds the 3'rd brush. The adjustment is made by moving the 3'rd brush in relation to the two fixed brushes.

Moving the third brush towards the main brush increases the output, and moving the third brush away from the main brush decreases the output. The ideal setting is for the third brush to be 3 1/2 to 4 com. bars away from the main brush on the armature. Also, when then generator is rebuilt, it is a must that the correct field coils for the 943 B generator be installed or you will continue to have output problems. The same is true for the armature as well. :eek: :eek: