22 ft donzi classic 1986 ,350ci alpha one gen 1 ?

[robana]

i am looking for the correct gear ratio for my setup 1986 350ci ,260 hp,alpha one outdrive . i have a 1.50 gear in it now,but only get 4100 rpm and 38 mph with my 21"pitch clever prop which came with boat,i did have 4800 rpm , and 49mph with first alpha drive that came with boat. please let me know which gears i need and or what could be wrong thanks bob.call me 1 516 754 1763.

[biggiefl]

Do a comprssion test. You should have a 1.5 ratio unless a BBC Alpha 1:32. Even if you have the 1:32 it would do better than 38. 38 means you have about 150hp so look at the engine.

[Walt. H.]

I'd start with checking to make sure that you're actually getting full throttle at the carburetor when you have the control throttle at the wide open position, and the secondaries are opening also and not stuck closed.
Since you are definitely not over propped or incorrectly geared.