Does anyone know what a OMC 305 should be turning for top rpm's? I have a 21 pitch stainless prop and its only turning 4000 wide open... Seems way too low. Anyone have any input? Thanks

You didn't give any boat details. However, if you don't have the manual for your boat, I believe the max rpm is 4400-4600.

check to make sure your throttle blades (carb blades) are opening fully. Look down the bores...they should be straight up and down. Whens the last time it had a COMPLETE tune-up ?