Your right! I was going that route, but no one could tell me which flywheel to run! Internal balance vs. external, and on and on. The 355 has been redone throughout, flattop hypers. w/ raised rings, 2.02's, besides, it's the challenge, anybody can go fast with a big block, or stroker! If and when the smblock peters out, I'll go that way. Thanks for the info. I'm new to the marine aspect of hi-perf.

That's a damn shame. I am currently building a 383 out of my '92 Merc 5.7L. Scat crank, TRW forged Flat tops, 2.02/1.6's, port matching, 9.7 SCR, 0.044 quench. My info is that all one-piece seal flywheels are externally balanced, so all you have to buy is an externally balanced damper. If your block was a 2-peice seal, then you have to spring for an externally balanced flywheel as well.

I'm building this engine over two seasons. This season I will run with the rebuilt stock heads and the cam from the 5.7L (Comp Cam XE-256-12) . Pretty weak, I know, but I still expect about 360 hp. Nest season, I'll upgrade to Dart Iron Eagle heads (72cc) and a roller cam (Comp Cam XM270HR). My biggest problem is the Alpha one outdrive.

Ya know that alpha won't do behind the final version 383, that's the main reason I didn't go that route, bravo and gimble housing are $$$$$. I'm still running the alpha, I'll just take it easy for a while, until I hit something underwater!!

220BR, I forgot to add this, do you use the 5.7 flywheel? If so, how do you account for the extra stroke on the bigger crank throw?

The answer is yes, I used the original 5.7L flywheel because it was orignally externally balanced. All one-pice seal GM 350s use an externally balanced flywheel. Evidently, the loss of material from the crank when going to the one-peice seal made GM use externally balanced flywheels.

It seems to be the luck of the draw on those Alphas. I have a buddy who has run a strong 383 thru a Model I (pre-Alpha) for three seasons. He even upped the gears to 1.89, which increases the stress on the lower unit. I bought a drive shower to help cool the Alpha. I just won't do WOT hole shots.

That does piss me off!, you didn't get any vibration with the 383? Enlighten me on the " drive shower"?

220BR, What boat, prop, mph, and rpm are you doing?

Whoa, there. Haven't put the engine in yet. USA Racing here in Houston is building the long block for me. They routinely balance stroker assemblies using the one piece seal flywheel with a new, externally balanced damper. I expect to get the engine back before Memorial day and may even be wet that weekend.

Drive shower is just a length of stainless tubing that is shaped to bolt to the drive so that the ends are at the cavitiation plate and the shower holes are up near the top plate. Under way, water is forced up and out to cool the exhaust passage in the drive. Really only useful if you are thru-prop instead of thru-hull.

Keep us posted, I'm curios to see what it does?