Carb Float Bowl Breather/Overflow
My last 912 ULS powered aircraft had the carburettor float bowl breather tubes venting into the engine compartment - over 10 years, never a problem and never noticed any fuel exiting from the tubes.
My new aircraft/new engine has a carburetor air box. The breather tubes are connected to the air box. The air box has a drain point, on each side, at the bottom of the air box. The drain points each have a tube, connected by a "T" piece, into one tube which terminates in a "catch can". The catch can will accumulate about 20ml fuel per one hour flight.
This is a relatively recent occurrence, with no fuel being collected during 5 hrs of pre test flight ground runs.
I have weighed the floats and found them to be just within specifications.
The engine is running well.
I am inclined to think that the floats have had time to absorb some fuel and are now less buoyant than when new. This is effecting how quickly the floats are closing off the float valve and possibly not providing the earlier pressure to close off the valve.
My questions:
Can fuel exiting the float bowl ever be considered normal?
Is the "fix" - removing the carburettors from engine, inverting carb, removing float bowl, measuring the float suspension brackets - adjusting if necessary?
