Propeller Balancing and Vibration Spectrum

Tracking is good. I do not think a bent propeller can be balanced. In this case, I was able to balance the propeller to 0.1 Inches Per Second Velocity, which is considered good for an airplane engine propeller.

The lower frequency vibrations could indicate other problems, such as a weak cylinder or something on the airframe loose. I am hoping someone might be familiar with the typical vibration spectrum for this engine and propeller combination.

The prop is freshly rebuilt and is indexed per the Coupe Capers article. Previously it was not properly indexed and it really shook on climbout. That article was very helpful.

I was complaining to my A&P about vibration. It wasn't extreme, but it was irritating. He checked the tracking on my McCauley, it was off by 1/4" He said that was it. The prop shop fixed the tracking, and noted it was already in balance. Weather has kept me from seeing if there is a difference. Tracking is something you can check yourself.

I am looking for guidance to interpret the vibration spectrum on my C8512F with a McCauley 7146 propeller.  The assembly balanced okay but I see a lot of low frequency vibration on the spectrum.  Is anyone familiar with this?