I have always felt that my engine ran noticably smoother above 2300 and generally cruise 2300 - 2400 for that reason. The trouble with vibration is that it is so hard to describe to another pilot how much vibration you are getting. The C series engines all vibrate more than an O-200 because the motor mounts are not as good but it is still hard to compare without flying some other coupes. Now would you describe your vibration as bone jarring or merely tooth rattling? Bob Condon
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