Here are a couple of pics of a carb fitted with the remote sensing static air line. The yellow tubing will go into the fuselage in an area of undisturbed air. This allows the carb to sense actual ambient air pressure and not the higher ram air pressure or prop blast pressure that is often present inside a cowling. It doesn't even have to be in a cowling to be problematic sometimes. If the installation ends up with the regulator cover facing the oncoming air stream while flying, or is in the prop blast, it can throw off your carb settings. It doesn't always happen; Bill from CH Ignitions calls it "black magic." Sometimes a remote static line isn't necessary. But if you are having problems with an engine running great on the ground but then going rich in the air, this is the first thing to look at. I generally just go ahead and install them on all my setups just to eliminate a potential problem area.

AV8TOR