Ed,
I didnt fly it with the cowl off the 1st few flights and it did the same thing. If I dont waterfall I can run it hard for about 20 minutes doing allsorts of maneuvers no problem. Doesnt appear to overheat and will idle in at about 2200rpms on landing with ease if I dont kill it in a waterfall.
To answer your question when the plane goes to inverted at the bottom of the maneuver the engine just fades out. No stuttering or acting up, no sudden death. I calling mudding out, the engine rapidly decelerates..... hangs on for a split second and then just quits. Could there be a carburetor adjustment I need to make. Im open about 2.5 rounds on the needle valve and its smoking pretty good just to be sure Im not too lean.

Help.[&o]

Mike