Originally Posted by
Hobbsy
You accomplished nothing by rotating the carb, that vent simply allows the diaphragm to flex as it regulates fuel flow. As long as that little hole is in the clear it will do it's job. Pictured is a Cline regulator which duplicates the regulator half of a Walbo carb. It doesn't matter how you mount it.
You misunderstand the problem and the solution. It was not that the atmospheric vent (the little hole you refer to) needed to be in a different position. The problem was needing to vent air (or fuel vapor) from inside the metering chamber so that you were full of liquid (fuel) inside the chamber, not a mix of liquid and gas. It was the air inside the metering chamber that caused the engine to sputter when the plane rolled and allowed the air to vent out of the chamber into the venturi. Sort of llike ingesting air bubbles in the fuel line. Rotating the carb, puts the metering chamber on the bottom so that air won't accumulate in the chamber.
Read Q13 on Saito's FAQ page for a Japanese-English explanation of the problem and their fix: "http://www.saito-mfg.com/english/faqgas.html
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