Making a Majestic Gas Engine Mixer

By Staff
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Modified needle and seat with pipefitting attached to top and copper line attached to bottom. Breather position simulated as in final assembly.
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Showing the addition of galvanized pipe attached to the bottom of mixer.
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Mixer components, left to right: Johne Deere 'E' needle and seat, 1/4-inch copper line with check valve soldered to bottom and 1/4-inch male pipe fitting with hole.
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Assembled unit on engine.

Any hobby or business that centers on obsolete and out-of-production parts certainly presents itself with problem-solving challenges. Our old engine hobby is certainly no exception.

Majestic antique gas engines have a unique mixer that’s simple in theory and operation, but can be a challenge in gas engine restoration if it’s missing or broken. An engine friend had such an engine sitting in his barn. It seemed a shame to have a somewhat rare, broken engine in its original state just taking up space for lack of a few parts. So, the Majestic engine winter project ended up in my care. My job was to get it running again and return it to the present owner. What follows is how I made a working Majestic mixer, starting with just the ‘water faucet’ intake breather.

This creation was entirely done without a lathe, although one step could have been accomplished on a lathe for appearance purposes only.

Step one: Do some homework on an original Majestic mixer to study its form and function. This was easily accomplished through another local engine friend that owns the same make of mixer. In addition to seeing the real thing, a photocopied Majestic owner’s manual page showing the mixer’s internal workings was provided by Jimmy Priestley, who’s done a lot of research on Majestic engines. I was becoming convinced that a working mixer could be made without any modifications to the original breather, so if the original parts ever became available in the future, they could be installed in this engine.

Experts will undoubtedly notice that my solution varies slightly from the original design on one internal part, but let’s keep our objective in focus: making a working mixer without the use of a lathe, keeping the original pieces untouched and getting the engine operational again.

The following items went into the manufacture of the mixer: a needle and seat from a John Deere ‘E’ engine and a check valve soldered to a length of 1/4-inch copper tubing, purchased from a major old-engine parts supplier. Any 1/4-inch brass fitting that has a male pipe thread and a hole in the middle is also needed. The needle and seat need to be modified since it’s installed differently in the Majestic mixer when compared to an ‘E’ engine.

Step two: Remove the external threads and wrench flats from the seat. Remove enough so the seat can be slid down from the top into the breather. Remember the needle is vertical on this mixer style, so your adjusting knob will be in the upward position.

Step three: Drill out your separate 1/4-inch brass fitting so it fits tightly over the seat under the needle valve. Don’t drill all the way through the fitting, but leave an internal shoulder so your fuel outlet will be as near to the center of incoming air through the breather. The amount you drill out will determine the depth of the needle and seat. The top of the mixer is tapped for a 1/4-inch pipe thread, and this fitting -when attached to the seat – will serve to secure it to the breather from the top. Solder or epoxy it now.

Step four: Screw a 7-inch length of 1/4-inch galvanized pipe into the bottom of the breather. There should be threads for this in the breather. The 7-inch specification is for a 5 HP engine. Just make your pipe long enough to keep the fuel line level from the tank to the bottom of the mixer. The variation from the original design shows up here because the original internal pipe sealed the top of this galvanized pipe to keep the gas from overflowing in the mixer if the fuel level in the tank was higher than the 7-inch pipe. If you’re doing a complete restoration where you need a new tank, keep the tank’s fuel level below this specification.

Now, screw the needle and seat into the top of the breather, slide your copper line with the check valve up into the bottom of the seat to determine carefully where your copper line needs to be cut so the check valve is near the bottom of the 7-inch pipe. Remove excess copper line, cut it to proper length and solder it into the bottom of the seat, making sure the needle and seat will screw into the breather without bottoming out before the fuel outlet centers itself in the intake air stream. You may have to cut some off the bottom of the seat before you solder it together – just be sure to leave enough on the bottom of the seat to slide the copper line into before soldering. Also, keep in mind the fuel outlet hole in the needle and seat should point toward the flow direction of incoming air for best results. This can be marked with a file on the outside of the top fitting before final assembly.

Once assembled onto the breather, you’ll be able to unscrew the needle and seat from the top, and pull it straight up out of the 7-inch piece of pipe with the copper line and check valve all as one piece, leaving the galvanized pipe in place. This follows the original design, and when installed and plumbed on an engine with a good spark, good compression and fresh fuel, it works!

This was written to help collectors with Majestic engines who are waiting for the original parts to show up. It’s a feasible project for most anyone, intended as a temporary solution until the correct items become available. I only hope the experts will realize our original objectives before commenting on this project.

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