In article ,
"Denis Marier" wrote:

My observation is get the pitch of your propeller verified by a prop.
shop before doing anything.

snip On my prop. I had 12 X 12 stamped on the hub. The actual
pitch was two degrees less.

Full agreement. Ours averaged the right pitch, but one blade was an inch
shy, the other an inch high. Fixing that got rid of a lot of vibration.