1940s Blue Diamond Generator AKA Gas-O-Lectric Plant AKA Pioneer Gen-E-Motor

I'm not sure what the official name for this generator is, but I'll call it a Blue Diamond Generator since that is the name at the top of the tag. All three names in the title are on the tag in various places, so I guess folks can take their pick as to which one to use.

Below is a photo of the tag showing this thing generates both AC and DC power, 300 watts of 110v AC (1.8 amps) and 200 watts of 7.5v DC (27 amps). I presume the DC is so this generator can charge a 6v car/tractor battery for some farmer who lived off-grid like so many rural farms way back when. It kind of dates this generator to the 1940s.

The generator didn't produce a spark when I got it. A gent in the tractor club gave the generator to me but I figured it couldn't be anything too terribly difficult to sort out. And you know what? It wasn't. Well, sort of. I spent two or three hours fiddling with things before finding out the simple solution that I should have tried right away. But first, let's disassemble this thing.

The engine has two flywheels, an inner one inside the shroud and an external one. Kind of weird but cool also. Below is the external flywheel removed from the engine. And by the way, IT THREADS OFF the crankshaft (after removing the jam nut). I initially tried a puller but soon found that wasn't working, so I inspected things and noticed the thing was threaded on.

This next photo is of the inner flywheel, and it does require a puller. I happened to have a piece of 3/8" flat bar that had two holes exactly the right spacing for the threaded holes in the flywheel, so I just needed to find two screws that fit and that were the right length. It was fairly easy to find them in BOB (bucket o' bolts).

This next photo shows the coil and points after getting the flywheel off.

The below photo shows the dastardly culprit, a condenser. It tested fine so I looked elsewhere for a problem. Points, coil, spark plug wire, spark plug, fuel, grounding issue. Nothing was working. But then I decided to try a different condenser and that's when I got spark. Yeah I know, why didn't I try that first?

Once the engine issue was sorted out (or so I thought), I decided to try and fix the small broken tab on the cast iron spark plug guard. It was broken when I got the generator. I'm not sure why it's blue...

I tacked the two pieces together with a small tack weld, then I brazed the joint.

Here are the after photos.

And these show it after grinding things down.

I cut two rubber washers to fit under the spark plug guard to hopefully cushion the delicate tabs on the cover.

This next photo shows the spark plug guard back in place. I didn't have any blue paint so I used your basic grey, which I think looks better than the blue.

With the generator back up and running, I realized the governor wasn't working at all. I could move the governor rod to both stops and the engine RPM didn't change one little iota. So off came the carburetor, as I thought the throttle blade might be missing. Nope, it was there.

This is a very basic carb, in fact I'd call it a fuel mixer, which is what is used on most hit-and-miss engines. There is no float bowl and the gas is just sucked up through a tube and check valve assembly into the venturi of the carb. There's a needle valve that adjusts how much gas flows in. Regarding the governor, all I had to do was to adjust the clamp on the end of the throttle plate rod so the governor would operate the plate correctly. I'm not 100% sure I got it right but at least now the generator puts out close to 110 volts at close to 60 hertz.

One thing I'd like to point out, adjusting the governor/engine RPM (and thus, voltage and frequency output) is by means of moving the spring on the governor rod to a hole in the rod to get the engine to run somewhat close to the right RPM. It will never give exact voltage and hertz levels like any cheap generator made today but this little gem is just too cute.

And if you've held on for this long, here's a video to keep your mind captivated:

4/16/2025 Update:

It's a week later. The engine just didn't run very smoothly, was difficult to start, and it would die if I didn't have the choke on a bit. Today I decided to take out the gas check valve in the tank. The first thing I was surprised at was how the engine ran at all with the check valve being so caked with crud.

Surprise number two, once I cleaned off the crud, I noticed a crack running the length of the check valve body.

Fortunately I was able to solder up the crack using a 260 watt soldering gun.

Surprise number three, with everything back together, the engine ran great, was easy to start, and it didn't need any choke after warming up. Here's an after-fix video:

This generator looks very similar to a Johnson Chore Horse (or Iron Horse) generator, made by the Johnson Outboard Motor Company. I'm guessing Blue Diamond is just a rebadging of the Johnson, although Blue Diamond may have used only the Johnson engine and then made their own gas tank and generator head.

I can't find any vintage ads for Blue Diamond, but a Johnson ad says:

"Supply low cost electric light for house, barns and yards. The Johnson Chore-Horse, a gasoline fueled electric generator, provides brilliant, safe electric light. It does away with old fashioned, dangerous oil lamps and lanterns and makes evening chores a pleasure."

These small generators were meant to supply AC or DC voltage to run lights in a house or barn in rural areas back in the good ol' days. Supposedly these generators could run 14 hours at full load on one gallon of gas.

This image below shows a Tadco generator ad, another possibly rebadged Johnson, although Tadco generator badges state, "Made and Guaranteed by Tadco Australia." I got both the Johnson and Tadco images from the net.

Update 5/27/2025: A tractor club show is coming up and I plan on bringing this generator along so now is a good time to change the oil. Not much oil came out.

And not much went back in, maybe half a quart, but I guess it is a very small engine.