I have about 40 minutes on my new ZDZ 40, 92 Octane, Stihl petroleum oil at 40:1, Zinger Pro 20 x 10. Prop is perfectly balanced (all directions), no spinner. Prop tracking is bang on. Hall Sensor set at 7mm from TDC (Falkon ignition v 1.3). Low end mixture set to leanest idle with no gasping on transition, high end set to peak rpm minus 200. Mounted on 73" H9 Cap232.

Starts and runs fine (after I figured out that they shipped it with the carb spacer upside down!). Peak rpm 6900 (10 degrees celcius, 4300' elevation, less than 50% relative humidity).

Vibrating the crap out of my airplane!! Idle is rough, as expected with a brand new engine, but midrange makes the rudder flail with harmonic vibration, and the elevators are a flapping blur at full throttle. The only thing I can figure is that I drilled the prop so that I can't align the blades with the piston. That is, there are no bolt holes aligned axially. I have the prop set so that the blade is 30 degrees behind the piston at TDC - i.e. just coming up to compression at about 2 o'clock.

Number one - could this be the reason for the vibration, with an otherwise balanced prop? Do most people drill so that two of the six holes in line with the prop blades ?

Number two - can I safely drill a second set of holes between the existing ones on a wooden prop of this size?

Will this vibration settle out with some more engine time? My poor little Cap will be a pile of sticks within a few hours if I try to fly it this way. Help!

KD