stunthanger.com
Engine basics => Engine set up tips => Topic started by: Brian Courtice on July 10, 2022, 10:40:48 AM
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Runs very rich (too rich to be useful) with aircraft level. Instantly revs up as nose goes up, and gets leaner as angle increases. Over rich and dies with any down pitch.
Literally runs like a throttled rc engine, using pitch angle for throttle control.
The tank is built into the fuse(no hatch), but I'm thinking maybe a tank issue?
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Runs very rich (too rich to be useful) with aircraft level. Instantly revs up as nose goes up, and gets leaner as angle increases. Over rich and dies with any down pitch.
Literally runs like a throttled rc engine, using pitch angle for throttle control.
The tank is built into the fuse(no hatch), but I'm thinking maybe a tank issue?
Some of the experts will know for sure, but I think your venturi might be to big.
Good luck, Jerry
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I agree with Jerry, but I suggest you trade that engine to a collector for two or three good stunt engines.
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The Johnson SS (Stunt Supreme) isn't like any valuable collector's item. They were well-built, and Hi Johnson took the Orwick numbers and produced a nice stunt engine. The engine has a good, strong fuel draw, so run problems likely to be with the tank and not engine.
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If it's actually a 35SS it's built on the large shaft case. It should have an insert in the venturi and a .157" spray bar. if the insert is missing or a smaller spray bar ws installed it will greatly effect the fuel draw. The stock engine as built has plenty of suction and should run in a strong two/four. A leaking backplate gasket will also reduce fuel draw. They were never the big rage for stunt and vibrate quite a bit. If it's in good shape you can probably trade it or sell it and buy a more "stunt" oriented engine that's designed for some type of muffler