I have read somewhere that the IO360 should not be operated in the range 2200 - 2300 RPM, or somewhere around those figures.
I can't now find the original reference, can anybody help please?
Mine is fitted with an MTV 12 B.
This has to do with harmonic resonance some props have with certain engines. This is very common, lots of certified planes will have tachs that show a yellow arch in those RPM ranges. These are for specific prop/engine combinations the plane was certified with. Most all prop manufactures will have data on the prop restrictions. Usually ships with the prop manual/installation or online.