Flyer Freq
Posts: 906
Joined: 8/20/2002
From: Appleton, WI, USA
Status: offline
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quote:
ORIGINAL: Dean in Milwaukee
Well, got to the field with the drilled carb, and while it was improved, it still is a poor performer for 3d use. I'm going to try resealing the backplate and the carb to block junction, but I'm beginning to give up hope of this ever being a good 3d engine.
Dean, I hope I can talk you into not giving up. It is my opinion that drilling the carb may make the adjustment a bit touchier to achieve. I recommend replacing the carb body before giving up. There is a lot of talk about leaks in this engine, so I wanted to see what was really going on. I took and old glow plug and drilled it out and tapped it, to fit a nipple. I then installed the modified plug in the engine. I was then able to submerge the engine, with the muffler and carb blocked off and see where the leaks were. I expected bubbles around the throttle barrel, but only had one or two in a couple minutes time. That isn't enough of a leak to matter. I had a steady stream of bubbles around the base of the carb. I found that the rings around the carb throat were very stiff.(referring to my friends .47, not mine) I went to True Value Hardware, and purchased some new rings for the base of the carb. Some of these engines have two O-rings. One at the base of the carb and one inside the throat, where the carb slides in. If you have two, change both. This solved any problems with the engine not wanting to shut down at idle. There were no leaks at the backplate or head gasket. After drying the engine out, and drowning it in Marvle Mystery Oil, I put it on a plane and went flying. Between the new carb body and the new O-rings, the engine ran beautifuly!
Now, the 3D thing! You may have noticed my posts on the uniflo tank setup. I had a friend fly my .47 with the new tank. He is a 4-stroke guru. He could not believe the performance coming from a 2-stroke. After doing a lot of hovering and 3D stuff I don't know the names of, I asked him what he thought of the engine/tank combo. He had one word for it, the that was SMOOOOOOOTH! I can't explain the difference, but you can really feel it!
As far as the one clunk or two clunk uniflo, it has to be two clunks. The single clunk design works well for control line, because you want the clunk at the edge of the tank, at the outside of the flying circle. Tying the two lines together allows this kind of control. Since an RC plane uses all three axis, the clunk has to be able to free float to every corner at the back of the tank. The only way to do this is to have one clunk for each line.
Dean, I don't know if it is worth a tank of gas to you, but if you want, order the carb body, and when it arrives drive up to Appleton for the day. I will help you get the demonds out of your engine. You can fly as my guest with the Valley Aero Modelers, provided you have AMA insurance. Let me know!
Andy
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Lose not thy airspeed, lest the ground rise up and smite thee!
If you want to make God laugh, tell Him your plans
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> RE: GMS Engine Tuning Problem 
RE: GMS Engine Tuning Problem - 
. Thanks Wayne! 
, so fine tuning efforts are going to have to wait a bit. 
