Troy,

That was a very good explanation, thanks for being so specific.

My engine has only 8 flights plus one hour on the bench and I'm still running it rich, I will lean it on four more flights, the airplane is big, the CAmodel/CPLR Osmose, the weight is fine, just the fuselage are and increased drag is the thing, and at that altitude with the engine still running rich it;s the problem, my engine leaned out on the last flight and quitted, I guess it is getting better, the idle is much more stable, I think I'm going to rework one of the velocity stacks to 10mm and try it again.

What do you think about the 18.1 prop on the 160?, and I will removed the velocity stack, I'm used to the YS throttle curve anyway, I will give up on the benefits for the extra punch, I will measure it with my dB meter to see how it is doing anway.

Best regards and thanks for the advices

Alejandro