Help with Stellings Boxes, IMCO Shorties adjustment.
 

What am I doing wrong here???
I have a Baja 342 - with the 33 Outlaw hull twin 525 HP engines and I have Stellings boxes with -2 in shorties. (mid hole on the Stellings box))
I have a prop shaft height of 3.25 and not getting great numbers - running bravo 4 blade or IMCO Shorty (-2).

What prop height have you seen the best results with?
Is the mercury lower or IMCO lower better? (Want to get the best bow lift)

Numbers:
With 496 Mag Ho's Before upgrades
All GPS
3500rpm @ 50.2mph
4000rpm @ 60.1mph
WOT @ 71.8mph

With 525+ HP Stellings boxes and IMCO shorties
All GPS Prop height 3.25in
3500rpm @ 41.8mph
4000rpm @ 50.4mph
WOT @ 64.7mph

With 525+ HP Stellings boxes and IMCO shorties
All GPS Prop height 4.25in Stock mercury lower
BAD porpousing and felt like the anchor was dragging handled like crap!
3500rpm @ 42.8mph
4000rpm @ 52.4mph
WOT @ 68.6mph

Anybody have suggestions? Thanks!

uses the stock lowers. i did the same boat minus boxes and gained nothing,
. lost the leverage needed to lift the bow high enough to reduce wetted surface area of bottom. plus the imco will slow you down and really doesnt help out till near or at the 90 mark in most applications.

Tried to stock lowers and lost 2-3 mph at WOT and about 8 mph mid range. What prop height did you try - do you remember?

Keith are you in the Atlanta area?

Since the # get better by lowering the drive, go with lower hole on box and stock lower on drive.
Let the props spin inward ,on a baja (they like that ).

Spin the props in.

rbr2328 - Yes, in the Atlatna area. I live in Gainesville next to Thompson Bridge

Props are spinning in. I am trying 3.25 and 3.75 depth today with 4 blade bravo and 5 blabe maximus props.

I cant put the stock lowers on just yet... I dont feel like swapping al the gears back. I've had the drives apart literally 7-8 times and its getting old now.

Stellings boxes
 

Throw Stellings boxes in the trash ! Driveline eliminates drive coupler and is hard on drives on heavier boats........IMCO shaft will fit on center adjustment. Then you can use Merc coupler. Do not bolt driveline to flywheel or you will be buying drives. My 2c

You are somewhat right.
But if he goes with IMCO ,he needs to adjust the engine up/down to center it .
With Stellings you do not need to do that.
Plus in my 33 PP i never had a problem.
Now on 382 Formula ,i think running Bravos is stupid anyways (with big HP) !
I would run Konrads on a boat like that !
Unfortinatly the torsionshaft from IMCO comes apart too.
There is nothing ou there which lasts for ever !!!!

My boat has 400+ hours with Stellings boxes and the original drives. The first 100hrs was with 750hp. The last 300hrs has been with 502mpi's.

Yeah well I ran the Barvo 1 4 blades at 3.250 inches and got 67 MPH then rant he 5 blade maximu and got GREAT midrange rant at 70 MPH WOT and still off by 10 MPH

Broke the upper downshaft tonight! fkn hate my boat - I am over this sht! I was at 72 before and at 68 now with boxes and 200 more HP...

i have had good luck with the stellings on my single step fountain 35, boxes are in top hole with stock bravo drives running hydro 29 q4 props turning in, its a pain to get on plane but handles great at speed. What did you do to the engines? are you sure they are running right ?maybe try some small props and see if they turn max rpm. also try some hydro q4 props if you get on plane easy then your drives are not to high. if you cant get on plane then they are to high. are your drives toed in or out 1/8"?

The reason wy the downshaft broke is probable because of drag or blowout . That is also wy your speed is of.
First of all you did to many changes at once.
More HP ,then run it stock,- ad boxes at stock hight with stock lower,- now go up step by step ,if it gets better but u whant more then try lower case but go to stock hight with the box again and just try going higher again untill the optimim is reached.
If u try so many things at once how will you know whats wrong?
If you dial a boat in you have to do it step by step ,piriod !
First of all ,stay calm.:ernaehrung004:
If you wanna get your boat dialed in correctly ,let me know.
Scott.

I feel your pain,like I mentioned in my post in the Baja forum,I put a stellings box on my 272 single with big power,lost a solid 6 mph. In my ENDLESS misery of testing different props and spacers I ended up also shearing off a billet prop shaft trying to turn a maximus prop. The maximus gave me great cruising speed but still didn't bring the top end back,I hope you find the right combination,I finally gave up,Smitty

Ding, Ding, Ding, we have a winner!

Let me know if you deciode to get rid of the boxes, I am looking for a set.

no i do not.

how ever i have never seen any improvement in performance from boxes at the speeds your discussing.
only at higher speed do they make a difference and not big ones. the c.g must be considered when doing what you are doing. as i said leverage helps more than anything and is efeected most by c.g .

pulling the engines is most likely why you did the boxes at the same time, but as stated above too many changes dilutes your results of what worked.
i would say to pull the boxes and stick the stock lowers back on. most likely will run the fastest.
check with baja to see what speeds your boat with what ratio and x-dimension are running from the factory.

The boxes are still on with the stock lowers now at 5.5 inches. I know this is in the basement but the boat is running 4-6 MPH faster thru the whole rpm range (keep in mind the stock prop height on a larger Baja is 7.5 to 8.5 inches).

Also, I found out why the boat seemed down on power. We hooked it to a scan tool and the damn Stellings boxes universal joints are setting the knock sensors off - they retard the timing 20 degrees. Hows that for robbing power...

It seems like something is wrong with the drive line....noise? The u-joints in the drive shafts will not last long if you have much angle on them. The carrier bearing must also be set/shimmed with the Bravo alignment tool. If your boxes are 10+ years old, getting perfect alignment may take custom made angle shims...Stellings had machining/jig issues. Here is an easy method to check your driveshaft angle.
Buy/borrow a inexpensive digital level, move the bow by raising or lowering the trailer jack until the engine is level (the edge of head is generally a good reference place). When the engine is level, now see what the angle is on drive shaft....or measure from current boat position and do the math.
Short term, any driveshaft angle will likely work for testing, long term the u-joints will not last with a big angle. My data comes from experience and mostly from a Dana/Spicer engineer that said that a big HP in 6-10,000 lbs boat at high RPM was a crazy use for automotive designed u-joints and was WAY past any design criteria or intended use for any u-joint in their product line:eek:. His recommendation was a MAX of 2 degrees. I run mine at .5 degrees and replaced the u-joints every season when I raced.
Based on your recent engine issues, are you sure your testing with the IMCO -2" lowers is valid? There should have been some speed at the raised X unless their are other issues like excessive porposing (balance), hook in bottom, etc.
Going forward, try and only make one change per test. If you can borrow drive spacers, the testing is much easier. When you find the "spot", now move the boxes, engine height, re-rig, etc.

The universal joints are huge. They are the size of grapefruits. They are new boxes with less than 15 hours on them and the drive line is straight as an arrow and I used an alignment tool. The problem is the Stellings bolts direct where as the IMCO goes thru the original rubber mount. The metal to metal direct drive creates enought vibration to make knock sensors get up to 85 hertz - the Mercury scan tool picked it up and we traced it to the Stellings universals. We are in the process of both backing off the knock sensors with a reprogram and tring to find a rubber mount that goes in between the Stellings yolk and the flywheel.

I havn't read the whole thread, but what about working the propr to increase bow lift? Maybe even go back to old school 3 blade prop.

One of my customers had BBLADES re work some B1's that wouldn't trim at all, and now they trim the nose up and he picked up 5mph GPS.

Still only a 70mph boat, but better than 65.

3 blade Mirage actually picked up 1 mph on top of that, but it might have been a fluke.

The B1 is a lot better all around.

Forgive me if this is a repeat of someone else's post.

I understand the arguement, but to date I haven't had any problems/failures with connecting the driveline/shaft to the coupler that Stellings provides and connecting it directly to the flywheel, BUT.....I will agree with BenPerfected concerning the U-joints/Shims set-up. I have found (the hard way) in my boat, that the U-joints will begin to fail right around the 200hours mark---at least in this reference. And I put my drives thru U-joint hell before that---so, they may even last a little longer. And these are the "greasable" U-joints. I have replaced all U-joints in the driveline/shaft with non-greasable U-joints which are actually supposed to be a little stronger----not really sure if the non-greasable U-joints are the better way to go or not.

We were unable to get the angle on being able to get the grease hose on the ZERTS fitting of the U-joints that are/were closest to the flywheel/coupler and (obviously) I believe this is why they failed---while we were still able to successfully grease the other ZERTS fittings in the other U-joints each year.

ben perfected knows what's up...if your angles are not correct in the boat, on that drive shaft. no matter how small the angle, the two u-joints will not cancel(vibration) each other as they are designed to do...boat manufactures and suppliers make this mistake WAY too often...

that aside...at the speed your running, the boxes are going to slow you down. the engine and drivetrain need to come way up. the water is way too clean back there and a very small change in the boat will net you large load changes.

Kieth.....keep us posted on your drive trials this year. thanx

BTW, I have had to learn to live with my own Stellings box/drive heigth/prop testing woes too. You must greese those U-joints at least once every year---at least that is what I do. Is it enough???---who knows, but I plan on replacing ALL the U-joints every 200 hours. I am currently running blue printed XR drives w/IMCO -2" shorties, and 5-bladed Hydromotive props with naturally aspirated 600+hp/680 lbs of torque per side. I have busted a lot of stuff back there....but for now everything seems to be okay. I know every situation is different, but I have several stories I had to live and learn/trial and error on that I could tell you about that may help you.

Pull the connector off of the knock sensor for a blast or two and see what gives before you reprogram. Let us know!!! We've all spent money only to slow down so be patient and act like nothing's wrong around your wife!!! :evilb: