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25HP Superior air valve questions

Larry Anger

Registered
The air valve in the superior engine we are rebuilding is a hurting unit. It has what looks like a thick rubber washer on the rod and is all cracked and torn and extremely hard. It looks like it was made by someone with a dull axe. The parts page I have shows items 43 - rubber washer, 43-B - fibre washer, and 44 - plate for air valve. Do any of you experts have first hand knowledge working on one of these valves that could offer any advice on making these parts. the metal plate looks in good usable condition. I was wondering if a piece of heavy rubber conveyor belting would be ok to use as the rubber disk? The ugly piece that was in there seemed to be cup shaped. It also had nails through it and through small holes in the metal plate and bent over. I appears it was complete fabricobbled unit.
 

Larry Anger

Registered
What air valve? Air start valve? Four cycle? Two cycle?

Bob
WB8NQW
Bob thanks for replying. Sorry for the lack of information. It's a 4 cycle engine and its the valve in the big mixer just above where the gas and air come into the mixer. It's a rubber disc about 4inches in diameter. The disc is on a 1/2inch diameter rod which is about 3/8" diameter which sticks out the top of the mixer through a large cap that screws off.
 

Bob Willman

Subscriber
Last Subscription Date
02/16/2020
I have a 25hp Type C 2 cycle from the middle 1930s so I am not familiar with the 4 cycle models.

Bob
WB8NQW
 

Kirk Taylor

Registered
The air valve in the superior engine we are rebuilding is a hurting unit. It has what looks like a thick rubber washer on the rod and is all cracked and torn and extremely hard. It looks like it was made by someone with a dull axe. The parts page I have shows items 43 - rubber washer, 43-B - fibre washer, and 44 - plate for air valve. Do any of you experts have first hand knowledge working on one of these valves that could offer any advice on making these parts. the metal plate looks in good usable condition. I was wondering if a piece of heavy rubber conveyor belting would be ok to use as the rubber disk? The ugly piece that was in there seemed to be cup shaped. It also had nails through it and through small holes in the metal plate and bent over. I appears it was complete fabricobbled unit.
Larry,
The composition of the disc isn't critical. Leather or rubber are fine. The purpose of the disc is to shut off the flow of fuel between intake strokes. As such, the face of the disc needs to be flat and large enough in diameter to cover both the gas inlet and the air inlet. On the intake stroke, the incoming air lifts the disc allowing the gas to also flow. Whatever material you use needs to be modestly pliable in order to make good contact with the sealing surfaces in the mixer.

Kirk
 

W.P.Klein

Sponsor
Last Subscription Date
01/19/2020
I just had mine out a couple weeks ago- fortunately mine was in good condition. Keep in mind that propane is a petroleum product and choose a rubber that will not soften or bloat from it. Bill Klein
 

Kirk Taylor

Registered
I just had mine out a couple weeks ago- fortunately mine was in good condition. Keep in mind that propane is a petroleum product and choose a rubber that will not soften or bloat from it. Bill Klein
That is a good point. A test would be to toss a chunk of the prospect material into some kerosene or diesel fuel overnight to see if it's stable.
 

PEJPE

Subscriber
Last Subscription Date
07/12/2019
I am interested in your solution. The inside of my carburator is empty. It occurs to me that proper operation may be sensitive to the weight.
 

Larry Anger

Registered
I am interested in your solution. The inside of my carburator is empty. It occurs to me that proper operation may be sensitive to the weight.
I wondered the same thing. When the piston goes back on the intake stroke I would think it would create a high enough vucuum to lift quite a big weight. Is your engine missing the entire valve inside the mixer?
 

PEJPE

Subscriber
Last Subscription Date
07/12/2019
Only the stem remains. I am thinking it should be just heavy enough to resist the gas pressure. Is there a spring?
 

Larry Anger

Registered
Only the stem remains. I am thinking it should be just heavy enough to resist the gas pressure. Is there a spring?
Yes there is a spring on top of the valve disc. There is also a metal plate that goes on the rod. I made a new rod for our engine. I will try and get some pictures after we get this repaired so you can see what we are working with.
 
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