I have been reading up on engine builds since I have to pull the stock 260hp Merc out of my '87 CC 230 Scorpion.
The engine is an '86, so it's a 1 pc rear main with perimeter bolt valve cover old style heads.
We do a lot of river running, very rarely do we do wide open running. The boat ran 53 mph once, and would average 40 WOT. The engine had a tuliped valve but ran fine at lower cruising speeds, so this past year I pulled the heads to find an exhaust manifold leaked in 2 cylinders.
The question I have that i couldn't really find is, if the main thing we do is cruising, would a stout 350 put me @ 55-58 mph? A local machine shop that builds a lot of short track & marine engines suggested a 350 over a 383 for longevity.
I don't have any experience with a 383, haven't done a small block in over 20 years, and never built a marine engine, so any honest input would be greatly appreciated!
Thanks in advance.
Jody

I would go with the 350 for your purposes. Should work well.

i would not waste energy on a 15 year old 350 boat motor. get a core that spent it's life with antifreeze instead of brackish raw water in it. a whole lot of your current engine has dissolved and gone out the exhaust with cooling water. unless this is a closed cooling system boat. and i have never seen a 23 scorpion with a heat exchanger. 350 blocks are cheap. although there weren't many 1 piece blocks with mech fuel pump mounts. they were mostly in the TBI-TPI era. you will need a clutch flywheel, coupler and oil pan to go to a 2-piece block. cheap and easy to find.

Motors built the same way, the 383 will do everything the 350 will do and then some, with less RPM.

look at your casting number on your block to see what you have. I have an 86 - 272 formula and just pulled two 350's out of it that had the older two piece main seal on them.

I agree on find a new engine, one with a roller cam. Lots of truck engines out there that are nice. Get one with the vortec heads also.

What year truck is the one to look for ? Will it have a fuel pump pad ? I ask because I have a really nice 1982 21 Formula as a beater that has a 260 , I want it to run 65

I am not 100% certain but I think the last mechanical pump 350's were 2000 models.

Anything '86 and later will have the 1: piece rear main seal and will easily accept Vortec heads/roller cam, etc.

A Vortec 350 with a ZZ4 roller cam, 650 CFM+ carb and a hot ignition will take that 21' Formula into the mid 60's with the right prop. I'm dropping 2: 355 Vortecs with Comp Marine cams in my 255 Liberator and I'm pretty sure I'll run past 65 with ease.

http://www.offshoreonly.com/forums/f...or-update.html

A 383 is fairly easy to put together ...but a 350 is easier.

Just My opinion:

Go to the Michigan Motorz website and look at the 315HP -350 carburated marine engine partial engine package 5.7-ISilver@just under $4K. You'll be way ahead on a warrantied ready to drop in an run engine package for your boat type and use.

Best Regards,
Ray @ Raylar

NO replacement for displacement !!!!!!!! If your engine builder can't make a 383 live as long as a 350 find a new engine builder.

stroke is torque, and that is what spins props. pistons and aftermarket crank are about same price for 383 as 350. extra expense is harmonic balancer and getting a 350, or better yet 454 flywheel custom balanced for the externally balanced 383 crank. 400 small block clutch flywheels didn't exist in the 70's. there sure as hell ain't none now. i have a pair of 355's in my nova. just got it back dirt cheap. doing the interior this year so they stay for now. but i am tempted...