ORIGINAL: bkdavy
First, any plane at idle, held vertical for several seconds, is going to die. There isn't enough exhaust pressure and suction to draw fuel. The plane is never going to fly in that position anyway (at least not at idle).
I helped a club member tune up his .46 AX last weekend on a profile Katana. The guy was having a heck of a time getting his engine to run reliably even though it was a used engine.
He had been monkeying with it far too much. I set it back to the recommended settings and started tuning from there.
He held it at idle for over 2 minutes nose up with a fairly slow idle ( 1800-1900 RPM ) . It held just fine.
Now that said, his fuel lines were pretty short, so I don't know how much this affected things. ( shorter tubes = less pressure required ).
But usually I try to shoot for a good idle nose up with about 1/2 to 1/3 of a tank, held for over 30 seconds and likewise nose down without cutting out. That is as long as the clunk is not uncovered.
Uniflow systems also help eliminate problems with the lower pressure at idle.
I'd shoot for a reliable idle nose up and down, which will help prevent deadsticks overall.