Full Engine Teardown - Rebuild or Buy Crate

[buckbambino]

It's getting close to that time of year!  I'm in a tough spot with my boat, and am just jumping into getting the engine rebuild or replaced.  I got a lot of great advice from the group last fall so thank you.  Last week I tore the 351W all the way down.  Catastrophic failure!  No. 2 cyclinder exhaust valve dropped (loose keepers) causing the piston to shatter into dozens of pieces.  Nasty.  Luckly, we were at idle when it happened. 

1980 engine and boat, likely never rebuild and mostly neglected by previous owners.  I found lots water in the oil, and a rusty cylinder during the tear down.  A few plugged cooling passages in the heads - mostly rust and a little water impeller chunk.  I suspect head gasket leakage in regards to the water in the oil.  No major bearing damage.  If the heads and gaskets would have been replaced prior to the failure, this engine could have easily gone on for a few more years.  On that note, if anyone has an engine with a similar history to mine, I would suggest pulling the heads to take a quick look at the valves and replace the gaskets.

Onward and upward.  I am very open to others' suggestions or experience with replacing the engine.  Right now I am highly considering a machine shop to a full inspection/cleaning/machining of the small block and OEM crankshaft.  Along with this, I would replace the camshaft, rods, pistons, heads, etc. with new.  In the end I am looking to bump this thing up to 300-350hp.  What have you guys done with your 351W?  Any material upgrades, valve sizes, valve lift, or other specs I need to be aware of?  Maybe a crate engine is the way to go?

Other thoughts...
Transmission - As long as I have the engine out, I am thinking of tearing this apart for inspection/seal replacement.  Who here has done this?  Difficulty?  I was experiencing a strange jolting motion with the boat in reverse last summer.  During the teardown I found the transmission cable was likely not fully engaging reverse.  Could this have caused the symptom I described?  Can the standard Borg Warner Velvet Drive handle 350hp?

Drive Shaft - In other discussions the 1" vs 1.25" shaft for increased HP has been debated.  I feel comfortable running a 1" shaft up to 350hp even if it is not recommended.  My shaft has lost 0.001" where it sits in the bearing.  Is there a stated tolerance/spec?  I am debating replacing the shaft.

As always thanks!

[RichV]

Ford based engines unlike GM do not have the option of an economic new engine from the OEM.  The quality of the rebuilt crates varies all over the map.  If you have a machine shop that you trust a local rebuild may be the best way to go.  If your existing engine has a lot of coorion in it you probably want to start with a clean core from a automobile.  What are your cost and performance goals for the new engine?

[buckbambino]

As far as cost goes, I'm willing to throw extra $$ at this thing to end up with a quality machine.  Performance-wise, I'm all ears.  I do want to end up with a more powerful engine.  Fast.  Fun.  Borderline scary.  On a scale of 1-10, 1 being lame and 10 being insane, I'd like an 8-9.  I want to be able to barefoot behind this thing.

As far as rust & corrosion goes, you bring up an interesting subject.  I've often thought about the long term effects of water on the block.  I've heard and read both sides to the argument on whether the block should be scraped or reused.  Any other thoughts?  I have slight damage in my No. 2 cylinder, if removing 0.030" wall thickness won't take care of it, the decision to get a new core will be made for me, as I have heard sleeving a cylinder is pricey$$.

 

[RonT]

FYI: your motor was rated at around 250-255HP rated at the crankshaft, in the mid 90's?? industry switched  to rating them at the propshaft, yours would be 10-15HP lower by todays stds. A modern 310HP marine engine rated at the propshaft would turn the 18' Skier into a controllable  beast (48-50MPH) which is about the limit to that hull. I would aim for 300-320 HP, that should pull several footers behind her unless your built like my brother.

[backfoot100]

I would definitely take the block to a good shop and let them determine it's condition. A good shop can work wonders. The key being a good shop. They're getting harder and harder to come by.

If it's good rebuild it. If it's bad you can source a used block from the bone yard and have that reworked pretty cheaply. Especially seeing as you have a standard rotation engine to start with.

Crate motors can be OK but I've heard lots of horror stories about them too. Buyer beware.

If it was mine, I would rebuild and look at my post from last fall in your other thread. Stock short block with GT40P heads, Performer RPM intake (or Stealth) and a new cam and you're easy hitting 300-315HP. With an Acme 541, it's a completely different boat.
My ski partner had an '80 CC with that exact combination. Keep in mind an '80 CC is a 17'6" boat so it's virtually the same size and weight as your Skier.

After the mods, we turned 53 MPH with a holeshot that pinned you back in the seat with some authority. It effortlessly pulled three footers. The only problem we had was that the secondaries came in right at barefoot speed and you either had 40MPH or 45MPH. I had to put a stiffer spring in the secondaries to slow down the opening rate which slowed it down to 51MPH WOT but made for a much better driving and skiing experience. It still pulled three footers effortlessly. We put well over 400hrs. on that boat without a hiccup.

[RichV]

If the water jackets have significant rust the machine shop should do a sonic check of cylinder wall thickess after etching the rust out.  The World Windsor jr head would be a great head for 351 ski boat engine, sometimes they can be found used for a resonable price.  The Speedmaster cast iron heads are priced very attractively, but may need some serious qc checks and rework before assembly.

[buckbambino]

Update:  I did a bore check this afternoon.  For the most part, bore wear was pretty even.  All cylinders were ~4.032" give or take a few thousandths.  The max bore I could measure on the damaged cylinder was 4.040".  Pistons were just shy of 4.000".  I'm giving up on this core and looking at all options. 

Any experience with aluminum heads on cast iron block in marine applications?

[backfoot100]

I wouldn't give up that block yet. Have a shop inspect it. That 351 should bore out to +.060 as long as the block is sound.
With a .060 overbore you're looking at something in the neighborhood of 360CI if nothing else changes.

In answering your question about heads....I personally haven't used aluminum but I know of at least three guys who have on tournament ski boat applications. Every case was high HP stroker applications. They're working fine to date but for what you're looking to accomplish I feel overkill. Put a set of cast iron heads on and with the money you save buy a QuickFuel 650 manual secondary marine carb and you'll be much happier performance wise. You'll suck more fuel but you'll have a big smile on your face.

[RichV]

The salt water guys treat aluminum heads as a life limited part, they anodize them for a little extra life.  You can install a heat exchanger and run antifreeze in the engine.  If you use the big valve version of the Dart or World  Windsor Senior cast iron heads you won't be giving up anything to a above average aluminum head.

[shyskier]

Just wondering if anyone has tried putting a 400cid crankshaft in a marine 351. I did that with my 77 F-150 ( .010 over pistons ) & it was a huge difference in torque and climbing hills in the mountains. I'm curious how it would work in a boat. My boat is a 350 so someone else will have to try.
Rebuild was under $1000 10 years ago ( crankshaft was free ) machine work + parts.

[backfoot100]

Just wondering if anyone has tried putting a 400cid crankshaft in a marine 351. I did that with my 77 F-150 ( .010 over pistons ) & it was a huge difference in torque and climbing hills in the mountains. I'm curious how it would work in a boat. My boat is a 350 so someone else will have to try.
Rebuild was under $1000 10 years ago ( crankshaft was free ) machine work + parts.

This is the starting point for the popular 408 stroker. I have a buddy that did it. Freaking awesome motor. Dyno'd it at 500+HP before installation. Aluminum heads, single plane intake, manual secondary custom Barry Grant Demon carb. 1 1/8" tranny upgrade. Better know what you're doing before attempting it. He's sharp when it comes to motors and kept throwing pistons or twisting propshafts. 408 builds compression really quick. He had to detune it to 9.5 compression, retard the timing and special order hardened propshafts (very expensive I might add). It's in a CC and runs 59.9MPH. He was constantly chasing the magical 60MPH but never actually hit it. Rebuilt it three times before he found the right combination of parts and tune.
Not for the faint of heart and definitely not as simple as installing a 400 crank. Nowhere near as cheap either.

[buckbambino]

A lot has happened with my boat since my last post, so I feel like I owe a followup post.  I ended up going with a re-machined long block I found locally on craigslist.  It was rebuild by S&J engines out of Washington state. https://www.sandjengines.com/  It was still on the crate in plastic so I took it for $1600.  I primarily went this route due to cost and schedule.  The cylinders/pistons are oversize 0.015" and everything else is marine stock some new some used parts.  The only performance improvement I went with this time around was a low profile performance intake manifold  - Edelbrock 2181.  I was able to reuse much of my old parts - the use of a sandblaster is amazing.

New:  Distributor, coil, intake, water pump, starter, damper, valve covers

Used: alternator, aux water pump, pulleys, damper (with new sleeve to protect new crank seal)

A few tips I learned along the way...
-The negative side of the ignition coil can be deceiving, it does not go to ground or it will never spark!
-Valve cover gaskets - I used black RTV on the cover to gasket side, and motor oil on the gasket to head side, so far works great and the cover can easily be removed for inspection and the gasket reused.
-Transmission inspection - I tore down the transmission, it was full of black gunk and all the springs were rusted and broke, the reverse piston seal was stuck pretty tight which is probably why the whole drive train shook in reverse.  New springs, gaskets, and seals and it's running fine.  I opted not to replace the clutch disks as it would have required new bearings and a press.  Keeping  things nice and clean is the key!
-Shaft - I did a run out measurement on my shaft using 'V' blocks and a dial indicator and found it had a high spot of 2 mils.  I used a clamp and some heat and reduced the runout to 0.5 mils
-Alignment - I will probably get scolded here but I will share that my coupling face to face gap was likely far greater than 3 mils.  I found the most important thing is that the strut bearing and shaft line up with the center of the shaft log.  I moved the motor and transmission the best I could and bolted it all up.  So far so good, I feel like this arrangement is very forgiving.
-I welded a NPT fitting to the oil pan and added threaded fittings and a valve for ease of oil changes - just connect a hose through the hull.  I did the first oil change after 15hrs and it worked great (compared to dumping 5 quarts into the bilge, been there).