81 wellcraft 180XL need to ski a big guy!

[samt]

Hey guys, long story short, got this boat for free, rebuilt lower, installed a "new" $300 motor. It had omc200 305, i put a 350 in thinking i would have power to spare, but seems i have a 175-190 HP motor. Drive is OMC 800 1.5:1. Prop is michigan 14.5" 17 pitch 3 blade stainless. Boat runs 40mph -@4300rpm with just me in it. Prop has some pretty big flaws, couple chunks gone, ect. Not sure how much this effects performance. Boat runs great with average skiers, and tubing, but when i get on skis it bogs down trying to pull me up. Im 300lb, not very limber, get asked where i played football all the time. Im planning to swap a cam or something in my motor this winter, try to get to 250HP. But if a $150 prop would make a difference i may try it for now. Does my prop being molested make a big difference? Searching for ideas. I have spent a good bit of time tuning, so im confident im getting all i can from my engine as it is. (Blue targetmaster 350)

 

[steelespike]

I'm no expert on the V8 setups but a 17" prop I think should be over revving.17" should do well pulling skiers.
​ If the prop has a lot of bow lift it may slow hole shot a little.
You should be able to get your prop repaired they may be able to tell you if it is the best selection for water sports.
They may be able to tweak the prop to help your hole shot.
I think your lightly loaded speed should be over 50 and may be over revving.
A healthy 18' 3.0 would make 4800 rpm and about 39 mph some applications may be able to run a 21" at about 43.
Both those props might struggle in water sports or heavy loads.
​ Are you guessing the hp based on performance or actual model numbers?
Does the boat respond to up trim?
Don't assume because its a new install that everything is right.
Be sure the timing is set right and advancing as it should.
Be sure throttle opens all the way.
Is the bottom clean and smooth?
Arte all cylinders firing?Good compression?

 

[Maclin]

Just echoing Steelespikes thoughts....In my opinion a 350 in that boat with that drive and a 17p prop should come out of the hole like a hot jetski and also way overrev at WOT, Steele has some good thoughts on what to check.

 

[SkiDad]

just a thought, but is your ski big enough? - you need to look at something like a Connelly Outlaw in 69" length or maybe a something else larger and wider like that - if you have a skinny ski it will be tough to get out. I'm 215 and run a 67" inch version of that ski and it gets me up in half the time of a skinny ski. And don't let that shaped ski fool you - it cuts plenty fast enough.

and/or look at a 4 blade in 17 pitch - that might help you also to get your stern up quicker - those V8's are not light.

 

[steelespike]

Reminds me of the neighbors home made skis from the 30s or 40s at least 9" wide and about 7' long.
So long that it flexed in the waves. Inner tube foot harness.We used it to tandem ski. 2 of us 180 pounders.
We started double,one on the big skis the other would step over onto the big skis.

 

[samt]

Thanks for the suggestions guys. I havent tested compression, ect. I will give it a once over And see if i can find an engine issue. It runs pretty smooth so i doubt i have a big ignition issue, but i guess its possible. Carb is an edelbrock 750 on aluminum intake. It has a standard delco vac advance distributor, guess i need to rebuild my mallory marine distributor, but i was being cheap and shoved this one it it since its HEI and had goods wires cap and rotor already on it. Totally guessing on HP, i was hoping this was a 250HP engine. It obviously isnt making even close. Boat is a deep V hull, it has some nicks and stuff, but not bad. My skis are normal ones, for large adults. Not sure of their measurement, but they are bigger than most, but not oversized at all.

 

[SkiDad]

OK I re-read your post - i thought you meant you skied on 1 ski - if 2 you should be fine with just getting the right prop for your setup. If you have SS prop and it has chunks gone then it's really not helping you. You can certainly run AL prop with no issues in a 17p and sometimes spin up faster - i see those on craigslist a lot. I'd stick with Michigan to get a predicable result.

I know a 4 years ago we hit a sandbar just lightly and didn't know it and I wondered why the boat didn't yank me up like normal - it was only a few minor chunks out of the alum prop and it really cut down on the power that day. I didn't really loose any top end but it seemed to not pull as hard - my wife driving even noticed that.

 

[samt]

Prop is pretty torn up, has a silver dollar size chunk out of it and looks like all the blades have been "dressed" with a grinder. It still boggs though when it tries to pull me up on a pair. I guess i can test compression, put a new fuel pump on just to make sure.

 

[SkiDad]

I'm not sure you need a new fuel pump. I would bet the prop based on what you said - when I first got my boat it has too big of a prop - it was fine for the kids but put me behind it and the engine would make that struggling sound. i still got up - but I dropped down 2 pitches and it didn't do that any longer. in your case the same pitch in good shape might be enough or if you want to try a lower pitch you just need to not run it all the way full thottle - I think 4600 is the max for that engine.

 

[samt]

Well i did some testing today. Compression 140-150. None below. Cold engine. Timing 8btdc Pulled plugs and they were black sooty, like totally sooted up. Googled new plugs and got them. Then i noticed that the plugs i bought are 1/2 inch or so shorter, i guess the plugs in it were for vortec heads? Not sure how many ponies that was costing me. Motor start and idles better sounds stronger too. I think they were sooted because last summer i was running a holley carb that was constantly flooding.