Coupers; I have vibration problems with a C-90-16F. The engine has about 2400 hr. TT with less than 40 hr. since MOH with new Millennium cylinders.
New engine mount bushings were installed at overhaul. The engine runs great, with no noticeable vibration except between 1800 and 2200 RPM. In that range, the vibration is significant. When reducing the power it almost feels like one cylinder has quit producing power. Adding carburetor heat or changing the mixture has no significant effect. Running on either magneto also does not change the vibration. I have checked the timing, all induction tubes, hoses, and clamps. The carburetor, a Marvel has been removed and bench checked in specs. I have rotated the prop 180 degrees, which helped slightly. I checked the prop run out, and there is minimal difference between blades. The prop was dynamically balanced, which also helped slightly. The prop is at the overhaul shop which has reported that there is nothing wrong with it after being told about the vibrations. I have run out of ideas. Has anyone else come across anything like this? If so, what solved the problem? I have no prior history on this engine/aircoupe other than the log books which show nothing of significance. HELP! Please. Lynn Nelsen __________________________________________________________________________ ______ To unsubscribe from this list please send mailto:[EMAIL PROTECTED] _________________________________________________________ Enlighten your in-box. http://www.topica.com/t/15
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