ORIGINAL: proptop

O.K. now for the other side... There has been debate about the need for this, but...
There are several of us here on RCU that have actually made an LA .46 run inverted...by (OMG ) drilling out the air bleed hole.

I have a Cermark Bobcat (low wing sport ship ) w/ an inverted engine. I couldn't keep it running long enough to shoot touch-and-go(s) because it would load up and quit.(extremely aggravating ...and the engine was / is broken in BTW )
I had the air bleed screw so far out that it actually fell out...and that's when I discovered that it needed more air than possable in the stock configuration, because it actually began to run better that way! (just a bit too much air though )

I can hear the others now..."change the tank location"...
I did that...I lowered the tank so it would run well while flying up-right, but when I rolled inverted, the engine would go too rich.

If you drill out the air bleed hole to 1/16 or 5/64 you will get your adjustability back.
Just make sure you don't get any alum. chips down in the engine of course...
I did mine w/ a pin vise, a little vaseline in the venturi to prevent chips from going down in the engine, and some Q-tips for clean-up.