Re: Need help - adjusting Cub voltage regulator

Posted by dnoha on October 08, 2001 at 05:44:01 from (205.245.122.225):

In Reply to: Need help - adjusting Cub voltage regulator posted by James (MO) on October 07, 2001 at 15:49:14:

James-

First, a disclaimer. My expertise on regulators is inversely proportional to the size of the internet. Take all the advise of other posters first, and resort to mine only as a last resort.

Disclaimers complete, here’s what I’ve discovered by messing with the regulator on my ’49 6 volt positive ground Cub:

There are two relays inside. When you’re standing on the right side of the Cub with the cover off the reg, the closest relay to you is what I’m thinking people call the “cutout”, and the relay closest to the engine is the one that actually “regulates” the voltage being produced by the generator.

From time to time my Cub stops charging too, at least according to the ammeter. Here’s what I’ve found:

When the engine is off, the cutout should be open (meaning the points aren’t touching, meaning the spring has won the battle against the relay, meaning the movable point is resting up against a post above it). I think the purpose of this relay is to insure that with the power off, no current can run through that “switch” and drain the battery. Maybe?

When I start my Cub, that relay quickly closes as the engine revs up. Now that we have a closed circuit, let’s take a look at the other relay.

Initially I’d expected that other relay to be either open or shut, depending on engine revs. What I’ve discovered is that it seems to be opening and closing so fast that you can’t really tell it is moving at all. If I watch carefully, I can see a tiny spark flashing where the points come together. I now gather that what’s happening is that this rapid opening and closing is how it manages to “regulate” the flow of current coming in from the generator.

So when my Cub quits charging, I first insure that the cutout relay is closing properly when I start the Cub and that it remains closed until I shut down the engine. Any problem here and I bend the little metal arm at the top (or bottom) of the spring until the spring tension is balanced properly and the relay acts as I’ve indicated it should.

I then turn my attention to the other relay. I learned several adjustments ago that sometimes no amount of spring bending affects the charging situation, but if I use a screwdriver to short between the movable point and the post containing the point it is supposed to close with, that I get a charge registered on the ammeter.

Ah ha!, I think. Points must be fouled. So with engine off, I take some fine grit sandpaper, insert between those points, press the points together lightly and pull the sandpaper out. I do this a time or two, then flip the sandpaper over and do it again a few times to clean the other side of the points. The sandpaper generally comes away with little dark smudges on it.

Then I crank her up again and I’m getting a charge! So I do a little bending of the arm the spring attaches to until I’ve got the ammeter showing no more than a 10 amp charge with operator speed lever set to max speed. I don’t know the right amount of charge but 10 seems to be fine. I then slow the engine down and as I do so the ammeter shows the charging rate dropping down gradually to about 0-3 amps or so at low idle.

I’ve only had my Cub for about 6 months, and have had to tinker with the reg three times now. I might be messing something up by doing this but so far so good.

Again, remember to take this advice with a large grain (block) of salt.

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