Short history on boat it's a 86 searay 268 weekender with a mercruiser 350 4bbl carbed engine connected to a alpha 1 outdrive.Bought the boat with a blown motor. Rebuilt the engine.On the fist sea trial she would wind up to 5300 to 5500 rpm's. Found it had the wrong outdrivew ratio 1.98 to1. replaced outdrive with a new sei unit 1.47 to 1 ratio. Now the boat maxes out at 4000 to 4200 rpm's with a 15.25X15 prop. Installed a 16X13 prop and max rpm's are still 4000 to 4200 rpm's. The boat will go righ to 3800 rpms when going full throttle from a dead stop then gradually climb in rpm's. The boat finally starts to plane at 4000 rpm's and going around 25 mph. All the usual suspects were checked tuneup boat being water logged and such. Tonight i pulled all the plugs and checked compression all cylinders show 120 to 125 psi. A small block chevy engine should be atleast 150 psi so i'm thinking the valves are a little tight. So i was going to remove the valve covers and loosen the rocker nuts a little to c if that brings up my compression. But would having low compression effect wot rpm's? The engine starts right up and runs smoothly.
