Re: Humming noise????
Could be Beethoven or might be Mozart!
No, actually, the reeds can act very much like the reeds in a saxophone or woodwinds. They don't always seal completely and a little air blows past them on crankcase compression. This causes them to vibrate with an almost musical tone.
Don't worry, old Forces and Chryslers had a specification for maximum opening whlie reeds were closed. something like .010 inch. Newer Forces have rubber coated reed blocks and I don't know if there is a specification for them, but any leakage is so minor it shouldn't affect engine performance.
