Ottawa ES Fuel Mixer Fixer

Have fun and save money by making your own fuel mixer


| October/November 2011



A schematic illustrating the new mixer that Ed made for his Ottawa

A schematic illustrating the new mixer that Ed made for his Ottawa (Figure 2 in the text).

I picked up a 4 HP 1922 Ottawa ES 4282 about two weeks after our fall show one year. It was headed for the scrap iron dumpster, as it was left over from the tag sale and no one wanted it. The piston was stuck, the water hopper had freeze cracks and most parts were missing. I thought that I would practice the art of removing a stuck piston and use the Ottawa ES for a yard ornament.

Well, after two years, I got the piston out and after another year got the freeze cracks welded. So, I decided to have fun trying to get it to run while minimizing expenses and made my own mixer.

Getting started

Figures 1, 2 and 3 show what I think the original mixer looked like as well as the one I made. The simpler the project, the better it comes out for me.

On the original, I was glad to see a simple fuel nozzle coming into one side of the venturi and the needle valve on the other side. The original mixer had a more elaborate air flow design for good engine performance under load and at high RPM, but I plan to run it at no load and at the slowest RPM I can get. So I expect my simpler mixer may work even better for my purposes.

Ball valve 

I have two 5-gallon buckets of scrap brass, and in going through them I found a 1-inch ball valve left over from some well work. This seemed ideal as the port on the engine head was 1-inch, and this valve came apart to allow the ball to be installed in it. It also had provisions for the valve stem where the packing box had a 3/8-inch pipe thread that I could use for the needle valve. This worked great as all I needed to do was install a 3/8-inch NP to 1/8-inch NP bushing and a 10-24 rod coupling for the needle. I would have preferred a 10-32 for the finer adjustment, but I think the 10-24 will work with the large knob.

Needle valve and fuel nozzle

To form the needle, I just chucked it up in the drill press and patiently used a file to form the needle. For the fuel nozzle, I used the tube from an old ballpoint pin after cleaning the old ink out. I took a lot of care to try to get the fuel nozzle and the needle to line up. I did this by putting a drill bit with some bushings snug in the bore where the 3/8-inch bushing went, and using the drill press and drill press vise, I marked the center of the hole for the fuel nozzle. Then, using a drill size for the nozzle, made the hole for the fuel nozzle.