I have a 3W75IUS, mounted inverted. When not in full power, level flight, the engine gets richer. I tried to lean the low needle but won't make anything as leaning it will caus the engine not to run anymore. I heard that it is because airflow problem which I strongly suspect it isn't the problem as there's no change in air flow when the airplane is inverted, same speed, level flight, etc.
- Is it possible that the excess of fuel spitting out the carb would richen it in this condition, as the carb inlet is now upwards ? If so how to correct it ?
- I heard about the weight of the diaprhagm. How could it be corrected ?

What are your experiences with this ?

Regards

Juan