Vibration

[Wes Hays]

I had the same problem with vibration in the 1900 to 2250 rpm range on my Alon when I first got it. In one of the manuals I received with my Alon, it talked about prop orientation on the engine. Sure enough when I checked, it was not as specified in the manual. My vibration was so bad it had broken the lord mounts on the instrument cluster.   The manual I have states that with the #1 cylinder on TDC, the #1 blade of the prop should be in the 10:00 postion as viewed sitting in the pilots seat. I could not find out how to determine the #1 blade on the prop so if anyone could help me with that, I would appreciate it. When I asked my A&P about it, he looked at me like I had lost all my marbles.   After I got home, I made the change and could not believe the difference. Although I had the same vibration @ around 1900 to 2250, it was not nearly as bad, and I could at least do some short term slow flight. (My wife was working on MCA). I still avoid these rpm ranges as a matter of practice because of the vibration.   I don't know if you have tried this or not, but it did help mine. Please accept apologies if you have already tried this.   Wes Hays N6372V Rotan, TX