454 carb problems

[m8kinulook]

ive got a 95 22' scarab with a 454 and i changed over the ignition to a hei box and put a 600cfm carb on it , now i can barely hit 50mph . the boat runs fine with no hessatation or popping. do i need to step up to a 750cfm carb? and im not too familar with these little small boats , what should be a decent speed im gonna guess 65? prop is a 3 blade 23 pitch.

[Rookie]

A 750 is the minimum size carb that should go on a 454 on a marine application. Is this the first time you ran the boat? Is this a Merc 330?

[m8kinulook]

yea ran the boat memorial day weekend with no problems. then took carb off to clean and gummed up the jets , threw a 600cfm on there with no luck , order a 750cfm today so hopefully this will solve my problems and yea its a merc 330