383 is working well

[NHGuy]

My new engine is in and enjoyed a first run on Monday. I want to thank all of you for the collected wisdom and experience that is shared in here. I'd have still been scratching my head on tons of little things without iboats, offshore only, and hotrodders .com.

Here it is:

1997 Vortec 350 4 Bolt Main Bearing Block
Bored .030? over to 4.030
Stroked .27 over to 3.75?
383 Cubic inches
Original 9.025? deck height
Block Clearanced for long stroke
Eagle CLI cast steel, internally balanced crankshaft for one piece rear seal
OE flywheel machined to remove balance weight and work with neutral balance crank
Forged TRW Flat top pistons .025? below deck
Piston rings were sized for additional clearance required in naturally aspirated marine use.
5.7? powdered metal original Chevrolet connecting rods
.015? stainless Steel Felpro shim type head gaskets
Quench distance of .040? for excellent fuel combustion and resistance to detonation

Static Compression 9.85:1
Dynamic Compression 8:1
Scorpion 1.6:1 roller self guided aluminum rockers
Dart Iron Eagle Vortec style SS cylinder heads, with 76cc chambers, small 165cc runners, & pushrod holes clearanced for lift
ARP Head bolts
Comp cams Beehive valve springs, keepers and retainers
Comp Cams Magnum Pushrods
Comp Cams Short Travel Roller Lifters at1/8 turn from zero preload
Comp Cams OE roller style CS 268XFI HR13 Cam
Valve Lift .570? Intake .565? Exhaust
Duration at .050 lift, 218 Intake, 224 Exhaust
Intake Centerline 109 degrees
Lobe separation 113 degrees
Comp Cams Double Roller Timing Chain
Mercruiser Thunderbolt V Ignition with knock sensing and mean best timing
8MM stainless core ignition wires
Weber WFB OE 4 barrel carburetor jetted 1 size up in the secondary side to .098?.
The Mercruiser Weber is the same as an Edelbrock 650 cfm both of which evolved from the Carter AFB, aluminum four barrel.
Mercruiser/Chevrolet dual plane high rise intake manifold
EMI Thunder aluminum exhaust manifolds with 3? extra height stainless long tail risers which reach to 6? from transom
Airtex 90 GPH electric fuel pump wired as Mercruiser
Alpha 1 Gen II drive
Filled with Amsoil Severe Gear 75w110 and outfitted it with
Mayfair drive cooling shower.
Michigan Wheel Apollo XHS 14 ? x 21? cupped Stainless Propeller
Idles and shifts at 750 rpm as Mercruiser designed, but it?s loud!
Runs 155 degrees underway.

Estimated 390 Horsepower at 5200rpm, 465 foot lb Torque at 4900 rpm.
But I have no proof.

Hoping for 60mph!
The boat is a 1987 Formula F223LS. Purchased April 2015 with a 1997 Mercruiser 350 MAG engine and same year Alpha 1 Gen II drive.
The boat?s published weight is 4000 lbs dry when built. I think this one is more like 4300.
It is 22? 3? loa with a 2 foot extended Silent Thunder swim platform/exhaust chamber.
Deadrise of 21 degrees at the transom. 80 gallons fuel capacity.

 

[tpenfield]

I hope it all goes well. did you post a video of your early morning startup?

 

[harleyman1975]

That's a lot of power for an alpha drive!

 

[Bondo]

Ayuh,..... I like the build,.... I hope it works out for ya in the long run, it oughta,.....

I lean towards the D-dish piston at 0" deck,....

But I still love yer build, 'n compression ratios,....
It must be Snappy,....

 

[NHGuy]

Yes Bondo I had some d dish piston in my sights til this machined block, crank, rods & bearings showed up. Then once I found a big enough combustion chamber to stay down in compression ratio I was OK. The larger chamber puts the dish area above the piston instead of inside it.

And, yes I am going to have to be really easy on the stick or I'll be crying about broken drive gears.

We get to give it a bit of a debut this coming weekend, there's a local Easter Seals Poker Run. We have a reservation, it should be great.

 

[NHGuy]

No video Ted. Once it started and ran smoothly it was time to install it in the boat. I had the exhaust off, engine on the mounts in about 90 minutes by myself using a rolling gantry. Then I had it plumbed and wired in another 2 hours. If I was 20 years younger It would have been quicker!
Then we loaded up and headed to the lake about 90 miles away, but when we got there it was blowing hard so we just waited for the next day.

 

[Scott Danforth]

Run it like you stole it

 

[bajaunderground]

Lake Winnapasuakee (sp?) has a 35mph speed limit if my memory serves me? I'm pretty sure all lakes/ponds have that as a limit in New Hampshire ! Sounds like a fun and quick set-up!

 

[NHGuy]

Yes it has a limit of 45. But there are times you can wring it out a little. Just need to be away from everybody else and safe.