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Posted by David Sherman [72.47.9.228] on Thursday, January 27, 2011 at 14:44:40 :
In Reply to: Re: Excellent data posted by Will (in IL) [98.215.26.138] on Thursday, January 27, 2011 at 12:44:06 :
It looks to me like the bottom on in your picture has the fine wire wound on its coil and the middle one has the heavy wire. The top one isn't adjustable, so it's the cut-out. It should be closed whenever the engine is running and open when the engine is stopped. If I'm right about the heavy coil being in the middle, try adjusting the lower one (the voltage coil).
First clip your voltmeter onto the battery posts and put it where you can see it. Just to check that thing seem to be working, press down on the armature (moving arm) on top of the voltage coil lightly with your finger. It's only 12 volts so it won't shock you. As you do, the battery voltage should drop. This confirms that opening those contacts does indeed cut the field current down and reduce the generator's output. If you press the armature of either the current or voltage coil all the way down, so its contacts are totally open, and yet the battery voltage and field voltage are still high, then something has shorted out inside the regulator. There are resistors mounted on the under-side of it that are worth looking at in case they're burned out or are shorted against something.
But assuming all works like it should, it's time to adjust the voltage. Looking at your excellent close-up picture, it doesn't look to me like the "knob" is really a voltage adjustment. It almost looks like a lock-nut on a screw that comes up from underneath that limits the maximum travel of the armature. That doesn't make a lot of sense to me, so maybe if you looked more closely you could figure out what it does. Bottom line is you might still need to bend the lower spring mounting tang. You want to reduce the voltage, so you want less voltage to be needed to open the points, so you want a lighter force on the spring, so that means bending the lower tang up (away from the base plate). I find that it's hard to do that carefully. You can't pry it up with a screwdriver unless you're careful to insulate the screwdriver from the base, since the spring and frame of the coil are "hot". You'll probably overshoot the mark and have not enough voltage. What I usually do is put a screwdriver against the lower tang from the top and then tap it lightly with a light hammer until I've gotten it bent back down just far enough to give me the right voltage. I once went to an old auto electric shop where the guy, who was retiring, gave me an NOS 6 volt regulator, saying nobody would want it any more, and then insisted on adjusting it for me even through it was fresh out of its 1940s box. He had a special tool to bend the tang neatly.
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