ive noticed a lot of posts about guys wanting to add some ponies to their small blocks, here is a link to my build from last year, it may help answer some questions you may have. after i got it together the thing runs great, im gonna work on fine tuning it this year, hope this helps.

http://www.offshoreonly.com/forums/d...under-way.html

Did you dyno it?

I built a great 388 sbc for my 242 last summer.

No dyno, wish I could have but don't have access to one and really not to worried about it, I've seen 64 mPh in the boat and I haven't dialed the carb in yet so I'd say I can get 65-66 pretty easily. It only ran 52-53 before so I was more than pleased with results

I generally dyno because you'll be able to tune it and seat the rings properly as well as ensure your cam has had a a good break in procedure. You can also see where peak torque is etc...

Here are my 355 specs in a Mariah 212Z. Went from 53 to 63.8 Top Speed

2 Bolt Main Block
Edelbrock 1409 Marine Carb 600CfM
Scat Rods 5.7 Pressed Pin forged
TRW L2256F + .030 Pistons Forged
Melling's M55Hv Oil Pump
Vortec 12558060 - SD8060A Heads
Comp Roller Tip cc1417-16 Rocker Arms
Comp Cams XM270HR Roller Cam
Hydraulic Roller Lifters
Cloyes True Roller timing set
Edelbrock 7516 RPM Air Gap
Crane Ignition HI-6M
Clevite Bearings
ARP Fasteners
GLM Aluminum Semi Tuned Exhaust Manifolds
Through Hull exhaust with Corsa exhaust tips
K&N Flame Arrestor
Powder Coated Stock Valve covers

I believe i am right around 350 HP at Flywheel. The Mariah 212Z is a narrow beam lightweight Bow (similar to a Stingray) and has a lot to do with the 10 extra mph. If the same motor was in a Sea Ray, Crownline, Cobalt of same length you would not be near 63.8mph (heavy wide beam boats) more like 58mph Max.

Congrats nice build

Mariah,
Are those flat tops with the Vortec heads? How's it do on pump gas, have to use super?

Magnum thanks for the thread, I'm building mine and have a few questions.
Thanks

I guess I could post my specs as well, I don't remember the detas on the bearings and timing chain and what not because my builder ordered all of that but I will post what I know

350 CID from a 1997 truck
903 vortec heads
Performer rpm intake
650 demon carb ( currently jetted to rich but fixin to fix that)
Lt4 hot cam kit with 1.6 roller rockers
9.8:1 flat top pistons ( forged )
Stock gm crank and rods
Block decked ( I think it's .013 in the hole )
Crank balanced
Stock merc exhaust for now
Thunder bolt Iv ignition

The pistons are flat tops. Yes I have to run premium fuel to avoid potential detonation. The compression is around 10:1 and the total timing is set at 30 BTC.

Another good tip is that I have always ran Amsoil 15w40 Diesel and Marine motor oil which I believe is a major part of an engines life.

Mariah,
I figured as much on the compression. X2 on the Amsoil, it's in everything I own.