With the engine is pulled...

[buckbambino]

Hey AS lovers,

So after a summer filled with lots of skiing fun, my old 351w bit the dust and needs a rebuild.   I've already got the engine on a stand, and I would love the community's input on some of the things I am pondering.

Engine:
-My boat is a 1981 skier with what I am assuming is the original 351w.
-I am considering a HP increase, any rule of thumb for what HP is ideal for this boat?
-Any special torque ranges ideal for a ski boat?  Low end, or mid range?
-I will likely have to stiffen up the aluminum engine mounts with through stringer bolts - any tips here?
-Upgrading to electronic advance while I'm at it.
-I found ~1 gallon of H20 in the engine oil after ~35hrs.  I suspect an internal gasket.  What have others seen?

Exhaust:
-Considering replacing exhaust tubes with new and adding silencers.  I understand the need to consider excessive heat with the tube/resin.  Any specs for these materials?
-Any luck with adding silencers?   Any recommendations?

Steering:
-I found the rudder wooden mount to be rotten, replacing with 3/4" plywood and p. resin, any tips/recommendations?
-Steering slop - I feel like I've narrowed it down to the steering assembly behind the wheel.  I've replaced the ball joint in the bilge and plan on replacing the cable & tube.  Has anyone seen the dash steering assembly wear?  Complete replacement or repair? 

Misc: 
-Considering painting the bilge white
-Found a crack on both my stainless exhaust coolers on an external weld.  Plan on having a weld shop do a simple seal weld.  Has anyone had water leak back into their engine who had a stainless exhaust cooler?  I don't suspect this, and am going to test the cooler with a hose.

- Definitely going to give S.B.P.O a call soon!

ANY tips or advice while the engine is out???

Thanks so much!
Charlie

[buckbambino]

My apologies for the terribly incorrect subject title

[RichV]

Ron has mentioned that 300hp is near the limit for the 1" prop shaft.  Typically the basic rpm versus torque characteristicsmare controlled by the cam, in a boat with wet exhaust you don't want to suck water back into the head.   Too much overlap between the exhuast closing and the intake opeing will allow the water from the exhaust to get into the engine.  The end result is you typically end up with a cam that gives you a useable torque curve from 0 to 5000 rpm.  Any of the major cam grinders like Comp Cams can set you up with a cam suited for ski boat usage.  The carbed HO Ford 351s claimed about 285 hp.  It should be relatively easy to achieve that or little more with a docile low maintenance engine.  The HO differed from the 230 hp versions with slightly better heads and a few degrees more cam duration.  This engine used the GT40 heads.  The slightly better GT40p heads were used for a number of years on Explorers and are relatively easy to find.  The aftermarket offers better heads and intakes, but I would stay away from aluminum unless you want to go to closed loop cooling.  I don't think there is a viable performance carb intake for ford, that can be used with raw water cooling.  If your existing block has a lot of corrosion in it you may want to start with a clean long block from a junkyard.  The 94 and later 351s  came with a hydraulic roller cam, I would look for one of these if you need to start with a clean core engine.

[backfoot100]

I disagree on Rich's 300HP limit for 1" prop shaft. I've got 300 hours on a 400HP stoker that's pushing 450Ft/LBs. torque on a 1" prop shaft without a problem. While prop testing I turned props 5900 RPM so a warmed 351 will be fine as long as the shaft is in good shape and your alignment is good. I personally feel that improper alignments cause more prop shaft failures than added HP but purely IMHO. If you have any grooves cut into your propshaft from an improper alignment that will weaken even a 1 1/8" shaft and promote failure. Make sure your alignment is spot on and the propshaft is in good shape.

That said, making 300HP on a stock 351 is easy and really wakes up performance. Get yourself a set of GT40P heads from Tristate or Clearwater Cylinder Heads for about $650-$700 shipped. Just make sure that they drill out the head bolt holes for 1/2" bolts and put in brass core plugs. Then add an Edelbrock Performer RPM or Holley Stealth intake. Even with the factory cam you'll make really close to 300HP. That's all with factory pushrods, lifters and rockers. Adding 1.7 rockers will give you a tad more punch without a problem too. I know of several guys that have done these upgrades without any issues at all. Top it off with an Acme 541 prop and you'll be amazed at the results. Heads, intake and prop will set you back a little over $1K and give you an easy 40HP boost over stock. That's a really impressive ROI.

Adding in a cam could push you close to a 50HP boost with the right one. The good news is that you have a standard rotation engine so cam options are about limitless. Any quality cam manufacturer has a good assortment of marine cams that should not have any worries with water intrusion. I would definitely consult the manufacturer if that's the way you want to go. I have some ideas about the duration specs of a cam but I'm not going there right now. The heads, intake and prop are a really nice upgrade and I personally wouldn't mess with a cam unless you indeed go through a complete rebuild.

My bigger concern is why you have water in the oil?? I would hate to go through a rebuild and put it all back together and have it happen again. I've seen guys do that exact thing so err on the side of caution. I would bet you wouldn't have needed to pull the engine or need a rebuild at all unless the block cracked which is the worst case scenario. Failure points are cracked exhaust manifolds, cracked intake or cracked heads. Pretty common issues really and easily fixed by a top end refit without engine removal. Much worse scenarios are a head gasket failure or cracked block. Did it overheat at all? Pressure test the exhaust manifolds to make sure they're OK. I would have definitely found out the source of your water intrusion before removing the engine but that's just me. Did you do a compression test or a leak down test before removal?

As for the through-bolts in the engine cradle. I thought that A/S always through-bolted their cradles but maybe they didn't on earlier model years. My '86 is through bolted. Maybe Ron can confirm that bit of info. If it's not through-bolted and something you want to look at, I'm here to tell you it's a lot more work than you would think. Go through my post here http://amskierboats.com/forum/index.php/topic,4342.0.html and you'll have all the info you're looking for including what it took to paint the bilge.


You mention both stainless exhaust coolers being cracked??? I have no idea what that is. Are you talking about an engine oil cooler (which there would probably only be one of and be brass) or do you mean the exhaust manifolds? If that's the case, see my questions above and you've probably found the source of your water intrusion so the next question again is....How and why are they cracked??? Overheated??? By the way, I assume if you are talking about the exhaust manifolds they're really aluminum unless they truly were stainless in earlier model years. Again, Ron might confirm that. Depending who the engine marinizer was may have used stainless but I find that pretty hard to believe. All I've seen are aluminum. If the manifolds are indeed cracked and what you're talking about welding, you definitely need to make sure that they're OK on the inner water jacket as well as the outside.

Steering helm can definitely be bad too but not that common. I know of a few that have gone bad. They can be replaced. I'm not so sure about fixing. Guess it depends on the issue if that's the case. Most helm issues are because of steering cable needing replacing or the rudder and ball joint need service.

Definitely reach out to Ron. He's forgotten more about these boats than I'll ever know. Keep us updated and hope all turns out well for you.

[backfoot100]

By the way, I forgot to mention it's a really cool boat. Looks to be in really nice shape. Congrats.

[RonT]

Shaft Diameter is a recommendation coming from the shaft manufacturers, 300HP is where I drew the line and went to 1.125" the Shaft Mfgs told us we were exceeding the rating with 1" shafting at around 250HP when rated at the propshaft. Older boats like this one were around 240-255 rated at the crankshaft putting them around 230-245 at the propshaft. In 1996 when I re-engineered the boats after WESMAR built them we went right to 300HP EFi motors rated at the propshaft, about a 70HP increase so I choose to move to the 1.125" shafting. To this day I cannot recall ever seeing or hearing of a ski boat twisting the shaft out strictly from too much HP. Failures come from vibrations and impacts, and minor impacts that result in vibrations. Had a customer's shaft break right behind the strut over this past weekend, the end of the shaft with prop went to the bottom. He said they hit something early in the summer, it did vibrate but thought it would last through the summer.

I use Gelcoat to paint the bilges

Motor mounts should be through bolted, however when doing a major overhaul I like to remove them and weld the aluminum angle ears that the motor mounts sit on,  to the frame, then re-bolt the frame to the stringers.  (new models are built this way)

If you have the Commander Stainless Steel exhaust I would have the repaired locally

[buckbambino]

Thanks for the great feedback and compliment.  Lots to consider.

I'll document my progress and decisions and follow back with the group.

As far as the stainless exhaust coolers go, see attached pictures.  I'm 99% certain these are the stainless commander ones.  The cracks are external on the welds, same spot on both coolers.  I'll pressure test one of these days and report back.
Charlie

[RonT]

Not used to seeing the underside but they look like the optional SS Commanders from here. The stainless "wrap" around the outside can be polished to look like a mirror.
These are called wet exhaust manifolds

[RichV]

Edelbrock makes marine intakes for Chevy, but unfortunately they don't make them for Ford.  I don't know how long a aluminum itake last on a cast iron block and heads with raw water cooling in fresh water.

http://www.edelbrock.com/automotive/mc/manifolds/marine.shtml

[backfoot100]

Charlie,
Ok, so I was corrected and found out that Commander did indeed have a true SS exhaust manifold option. Like Ron says, they can be patched and polished but I still wonder why they split in the first place. I ask again, did the engine overheat at all? If they split on the outside, I would definitely be concerned that they're OK on the inside before using them again.

Rich,
You can use a standard aluminum intake without issue in open cooling freshwater applications. The marine specific intakes are really designed for saltwater applications. I had an Edelbrock Performer installed on my engine for well over a decade and about 700hrs. running time before my rebuild. That intake is currently sitting in my garage waiting for a new application in excellent shape and perfectly usable.

[buckbambino]

Thanks for the sound advice.  It's been awhile but I need to give an update on the wet exhaust manifolds.  I tested them for internal leaks two ways.  1) Compressed Air, I put ~45psig on them and dipped them in water, no air leaking thru.  Probably way more air pressure than is needed, would do 20psig or less if I had to do it again.  2) I filled them with acetone and watched to see if they leaked through the exhaust.  Both manifolds tested OK, so I got them tig welded - 308 rod I believe is what was used.  See pics.

-As far as the root cause for why these cracked, I can only speculate, my thinking is either thermal fatigue or thermal differential between the hot exhaust and the cool jacket put a lot of stress on the weld.