351W Rebuild 1993 Ski Nautique

Engine was originally seized up due to all 8 cylinders being corroded so bad they were all locked up. The original Pro-Tec took a dump like so many more before it. This is why you replace exhaust manifolds. So salt water doesn't end up in your cylinders. Anyway heres what was done to the motor and the list of parts best I can remember right now.
Bored .030 over, new bearings all around, electronically balanced, align honed
9.6:1 Flat top pistons with free floating wrist pins
Original crank, connecting rods
Comp Xtreme Energy 264 hydraulic roller cam
Crane Cams hydraulic roller lifters
Comp Ultra Pro Magnum stell roller rockers
World Products Windsor Senior 200cc intake runners, 64cc combustion chambers
Double Roller timing set
MSD Ready to run marine Distributor
MSD 6T oval track ignition my buddy loaned me
Holley 80 gph mechanical fuel pump
Melling oil pump
Moroso 7 quart steel oil pan
Hardened pushrods
Bronze distributor gear
Edelbrock Rpm Air Gap intake manifold Gasket matched
PCM exhaust manifold ported and matched to the wayyyy bigger Windsor SR exhaust ports
ARP main bolts, head bolts, rod bolts, rocker studs, accessory bolts(12 pt stainless) valve cover studs, pretty much everything in or on the motor is ARP.
Stock carb though considering quick fuel 650 marine carb
As of now fine carb and ignition tuning hasn't been done just yet
Runs on 100LL Avgas
Freshwater Cooling
Acme 12.5x15.5 4 blade prop

Hope Everyone likes it! It was a project that started as a college summer project but as you can see it got kind of out of hand and went into the fall and just ran the third weekend of march. Should make about 400-425 HP at the crank, 430-440 Lb-ft torque. This is the first motor I've built so we had the machine shop assemble it but it has started a dangerous, expensive motor addiction for sure and I can't wait for my next project.

American Cylinder Head Exchange in Vero Beach, Florida did all the machining and assembly of the motor. I'm very happy with the work they did and if you watch the videos on the Flickr that I will link, watch how the motor never has any vibration from idle all the way through full throttle. They can balance a motor pretty damn well.

Heres the link...
https://www.flickr.com/photos/121394715@N07/

https://www.flickr.com/photos/121394715@N07/

The 89-96 1.23 boats have a lot of clearance under the engine- the reduction trans incorporates some down angle so the engine sits nearly flat. They are unlikely to struggle with aftermarket pan fitment like the 1:1 boats (or the tsc+ boats that dropped the engine down lower).

Cool project! I'll withhold comment on your hp guesstimate until you tell us how it runs out. :) have you put a GPS on it? How many rpm can it pull that 422? From the video, it's got more top end than my 90 for sure. Next time, feel free to use a less delicate touch on the throttle out of the hole and show us what it can really do, ha.

Will's dad here. The boat gps ran 49.6 on the second time out without any tuning. The prop is an acme 668 that we got from rstilley on this site. I have a friend here that is a boat and car race guy in his spare time. He's been at it since he could drive, and he wants to tune it in in the water. We have been working out the little stuff in the install, so we haven't been able to get together yet. I will give you a tach reading as soon as my avionics guys can figure out which wire to connect where! Hahaha! They're airplane guys. Not boat mechanics. The wiring harness on the engine side was lost in the shuffle and they've had to mesh the new ignition wiring and engine sensors wiring to the old boat harness. Thank god for friends who are mechanics! Right now everything works but the fuel gauge and the tach. It revs higher than the old engine with the old prop. But it sounds about right. The next run will have a tach readings! I think Will did a great job on the engine.Its been a great experience for him! Heck, I learned a little too!

Also, if anyone can answer this that would be great. With our new cooling system and the thermostat that came with it, the motor won't budge above 150 degrees. Granted the gauge could be incorrect and I haven't had a chance to shoot the thermostat housing with a pyrometer to check that. Assuming it is correct why would this be?

Compression is 9.6. Mainly because our family sells avgas and jet fuel so we have it around. The car gas we have seems to be about 88 octane so its just a matter of we have it and it would be better than the car gas we keep for our vehicles. Smells better burnt too haha

Can't see you having fouling trouble at that temp,your gauge could be off by 10*. Mine runs 120 tops depending on water temp and never had any issues. The cooling system is significantly different than yours though. Like Tim says get the gun out to be sure. Nice job,did you use the original block?

Hey Billy, load that project up along with your Dad, and head two hours north to Mt. Dora this weekend, Sunnyland antique Boat show, meet us all, and let us see that spectacular "project"? Dad will like it as it is the seaplane capitol of the world. You both will have a good time.

I'm glad Tim asked about the Hp, I kept talking myself out of hitting the post button.

The tach reads of of the negative post on the coil (might be a wire on the MSD box as well), I believe it's a grey wire.

We run that 668 on dad's 196 with the 409hp 6.0L and it pulls it up to the 5600rpm rev limiter. The boat is good for 53-55mph depending on conditions and weight placement. If you have a legit 425hp you should be seeing similar numbers, but if youre in the 50mph range, youre probably closer to 375hp or so and 5300-5400rpm. Just a guess! Will be interesting to see what your numbers are once its dialed in and you have a working tach.

What was the set up on the old motor? 5200rpm with the 668 or a different prop?

Joe's 500+hp stroker 408w that spins 6k rpm likes his 650cfm carb best... 600cfm has proven to be sufficient for a few other hot 351w builds that spun north of 5500 (Alan's '81 and hotboat's Martinique). Factory jetting was actually a little fat. I suspect theres not much to gain in the carb, at least CFM-wise. If you can pick up an improved carb like a BG or QF, that might be worth considering! Probably only need the 600cfm though. I do like the mechanical secondaries option if you can go that route... removes the transition to the secondaries at barefoot speeds.

JR_VIC had a hot motor in his '92 that was running in the low 50's, if I recall. Jody had an Apex powered '92 that would hit 49 as well. Not too many other NWZ's with hot motors though, at least not beyond the common GT40p upgrade that generally produces ~325hp. Im a bit north of that with exhaust and cam upgrades, but not by much- and my slow hull is only good for 46 on any given day. A legit 425hp should push the boat into the low to mid 50's.

Will let you know how the QF M-600 runs on a stock BBC PCM soon. Great looking little carb.

Only issue I see so far is the secondary closing linkage doesn't seat fully on the secondaries at idle so It may cause them to stick open slightly. Easy adjustment.

That's one thing I always make for damn sure is adjusted properly on holleys before I start dialing in idle rpm and mixture. A variable like that will make you scratch your head for days.