Repowering SCR 3000 from 4.3 to 5.7l

[Stilley902]

The problem is power and planing!

I have twin 4.3 Alpha 1 Gen 2 running 19P stainless props, the boat struggles to get on plane, top speed about 28mph the RPM is 3800-3900 max, cruises on plain at 26-28mpph at 3600rpm if i dip below 3600 is comes off plane.

I was thinking about prop swapping or going to 4 barrel carb set up from 2 barrel...

Once i start looking at options might be better to swap engines and sell old 4.3's

i am looking to chat with anyone who has same boat or same issue...

Thanks in advance

Shannon

[mmwjr]

You’ll need to verify with Mercruiser but I believe going to the 5.7’s will require a change in the drive gear ratio.