ORIGINAL: chuck l
There are frequent references to tuning the high speed needle for max rpm, then richening it for a 200rpm drop. Can some one explain the reason/theory for doing this? Can you really tell any difference when flying the plane?
That's the glow engine method IMO. I don't do that with my gassers. What I do is lean the high needle until the engine can no longer maintain a constant RPM at full throttle. I then richen it until the RPM's stay the same (for about 5-10 seconds anyway). The thing with the "200 RPM less" method is you don't know that simply 200 RPM less than the old setting is rich enough. It might still sag in uplines. Which is how other prople set their high needles. If they sag on an upline they land and richen it. They keep doing this until it's good. Both methods work, the flying one may be a little better. The reason many of these guys in this thread are talking funny cause they're prolly burned out repeating the same thing over and over in a new thread.
I never have engine problems and my gassers pull very strong and constant verticals. I can hear a gas engine that's too lean without using a tach (on the ground). The RPM's slowly drop and it sounds "weak" or "anemic". It's not that difficult to tune actually.