Colt with O-235 C1 It sounds like one cylinder is developing considerably more oomph than the others. When aircraft is at 800 ft you can hear this on the ground. Does make Static but takeoff performance is poor. VERY noisy. Will be doing Spin type compression check and run up with different Colt props and Optical Tach. Could 1 cylinder be off a R-2800 ? More realistic would be from a high compression O-235 L2C or similar. Valve Lash in agenda. Other thoughts?