ORIGINAL: NM2K
You must set the high speed needle for max rpm, minus 200-300 rpm with only an ounce of fuel in the tank. Then the engine's mixture will remain rich enough to prevent sagging as you burn off the fuel in the tank. Yes, the engine will sound rich when you fill the tank and restart after setting it this way. DON'T TOUCH THE NEEDLE VALVE! If you do, you'll be right back to sagging when away from shore after initial launch.
This happens because your engine uses suction to pull fuel to the carb. This is a very weak force and it is sensitive to the fuel pressure head.
Ed Cregger
I've been setting the mixture at 1/2 tank. But what I don't get is how drastic of a change in how it ran on the same plug and same fuel from one day to the next when the weather was literally, identical. Part of the problem with these engines (military) is they don't throttle well.. I don't know why, Mecoa hasn't told me yet. I'm willing to try it this way - which isnt much different from how I was setting it before just with less fuel.
I pulled the carb barrel and needle valve assembly out and looked it over. 2 little specs of what looked like plant matter. The engine did get a little water spray the other day. Otherwise, the inside of the carb looks fine. I'll run it at home here since I still have 2 or 3 more cycles to do on the TT .46, and go hit the pond..