Information must be posted.------What pitch prop?---What boat?----Does spark jump a gap of 3/8" on each lead?----Actual compression values.----Does timer base rotate fully?----Flywheel key checked?----Run with timing light ( one cylinder at a time ) to see if there is a spark issue.-----Shine a strong flashlight into each carburetor to compare fuel flow up the nozzle.-----Reed valves checked?
Wanted to post what was finally found. The lower power head gasket was letting water into the exhaust causing back pressure in the exhaust. Not sure why the mechanic even checked it but glad he did!
