Need help from Superior engine guys

[Howard Weaver]

I am restoring a Superior engine and have hit an unknown. Inside the gas and air mixing chamber is a stem and disc that had some kind of rubber ? on it to close off the gas and air inlets. Can anyone tell what this material should be? How thick? Also the surface of the gas inlet is a little higher than the air inlet surface. Is this correct? There is considerable rust and metal loss in here and i plan on grinding the surfaces smooth again. This is why i ask. Any and all help will be much apprecieated.
Howard Weaver

[Patrick McNallen]

I have a 35 HP Superior with the same set-up you describe. It seems to be a kind of demand regulator that feeds gas only during the intake stroke and also would shut off the gas if the engine stopped unexpectedly. The disc appears to be some kind of hard, black rubber about 1/2" thick. It is smooth on both sides. I think that the seating surfaces you mentioned should be level with each other and machined smooth to form a seat for the disc. A material called Delrin would make a very good replacement disc. It is machinable and tough enough to stand up to the job, and it has similar characteristics to the original material. The engine will run OK without the disc, but it probably will run better and use less gas with one in it. It might also prevent fire blowing out of the intake. My disc is not gas-tight unless I press down on the stem, but I think it is supposed to be. it's probably warped a little. I put a light spring on it to help it seat. I don't know if it originally had a spring or not. The gas feed pressure is supposed to be around 8 to 10 ounces for these engines, and if it is too high, it will lift the disc off its seat. My engine still has its tag, which gives the HP rating and serial number, but no RPM. It is my understanding that the 35 HP engines were rated at 190 RPM. They typically ran slower than that, and mine will run well with no load at about 60 to 70 RPM. It has badly worn valve stems, especially the intake, and the throttle shaft assembly is worn. If it had these problems corrected, I would expect it to run at 40 or 50 RPM.

[Howard Weaver]

Thanks very much for your responce. I was suprized that you say 1/2 thick material. The only piece of the rubber or whatever it is left is under the nut that holds the disc on the stem. I'm sure it has been squeezed down but the pieces of what is left measures about 3/16ths on an inch thick. There is the remains of 4 wires that must have been used to hold the outer part of the material on the disc. Also after further cleaning the seats are deffinatly different heights. In between the pitted spots there is machined surfaces that are about 1/16" different. Can't figure out why that should be. Thanks again for trying to help me out.
Howard Weaver

[Patrick McNallen]

The disc in my engine is at least 1/2" thick, and the "seats" in the mixer body are very close to level with each other. If I wipe everything clean and spray the mixer seats with a coat of Micromist, then put the disc and stem in place, the oil makes a nice "imprint" of both the outer and inner seat on the disc. I have another disc and stem assembly, and it is identical to the one in the engine, but it's too weathered to use. It may be that someone re-machined one of the seats in your mixer and made a stepped disc for it to accomodate the difference in seat height. The two discs that I have are well over 50 years old that I know of, and both of them have an identical cotterpin to secure the nut that holds the disc. They look to be factory assemblies. The one in the engine shows some wear on the stem, but the other one doesn't, and it may be new old stock. The serial number on my engine is 9011, and I think it is an earlier version, though I don't know when it was made. I think it would have been made sometime between 1906 and 1920. I have some crumbling original literature on Superiors that I can look through and see if I can learn any more about the mixer.

[Keith Kinney]

Our local Superior expert, he as a dozen or so of them, recomends removing the valve in the mixer you are talking about. He then plugs the hole where the rod goes through the top of the mixer. He claims it is unneeded when using an external gas control valve. He also says the engine will run better and use less fuel without the valve.
I used some heave rubber conveyor belting that I faced with some softer more plialbe rubber gasket material, that had glue already on the back of it. I picked it up at the auto parts store. It seems to have worked fine.
Keith

[Howard Weaver]

Hadn't considered removing the valve, but i'll certainly give that a try when i get ready to start it. I did order a 1/4" neoprene sheet and cut a disc out of it. The nut that holds everything together and the 4 wires keep it nice and tight to the metal disc of the valve. I'll let you know how things turn out when the time comes. Thanks
Howard