corry

I own an old hangar, nine giant scale ultimate. When I roll inverted, the engine goes very rich. The carburetor sticks slightly below the cowl which puts it slightly into the airstream. I think I need to form a deeper Cowell so the carburetor stays inside of a stable air pressure. What do you think? Have you ever had this problem before? If so, how did you solve the issue? Thank you for your help.

pacoflyer

My Feedback: (23)

I put a small metal damn in front of my 150's carb and that helped neutralize the pressure created by the airflow

Bossman59

IF you look on your carburetor, the pump side has a round flat plate. That plate has a hole in it. This allows the diaphragm to be able to move to pump and not have to fight air pressure build up. (think Im explaining this right). When you roll over you're disturbing the pressure with varying air flow over that hole. This causes the pump change fuel pressure erratically and you get the on and off burble.

The fix is to attach a nipple to that hole. Like a smoke fluid nipple thats used on a muffler, a small barb. I have JB welded them on before. Then take a piece of fuel line, attach it to the barb and run the fuel line into the fuselage where the air pressure will not disturbed. I have done this on numerous gassers I own and it clears the engine right up if you are getting the kind of problem you're discussing.