Anyone know any tips for messing around with a 4.3L V6 4v
190HP OMC Cobra I/O? Haveing a bit of trouble with my holeshot. Running a 19 pitch 3 blade stainless steel prop I believe. Just want to get a better holeshot because she's way too sensitve to weight placement in the boat and takes forever to plane out if you don't put people in the open front.

Trim tabs will help. Putting an 18 pitch will help but the engine my be at redline and you would lose top end also. Make sure the lower unit is all the way down when taking off. A boat like that will always have planing problems,its a forever battle. http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/confused.gif



Last edited by mxz7 at June 01, 2002, 9:11pm

Already running hydrofoil fins mounted on the leg. I think 18 might be too far. 19 slows it down to just over 40mph as it is.

It all depends on what your your top end rpms are supposed to be. for best alaroud perf you should be running just under redline at full trim. When I was playing with prop pitch I have found that sometimes a lower pitch can give me more topend if the higher pitch was not letting me pull the correct rpm. On my new Bayliner I had I got better top end and holeshot out of a 19 pitch over a 21 pitch that is because the 21 pitch was loading the motor too hard and not letting it rev enough.

my boat has a TORQUE SHIFT *prop(variable pitch) starts on an 11 pitch and swings to 26 if you let it,they are adjustable to tailor your rpm's.it took this boat 10.5 seconds to plane out new ,its now 8 years old and planes out in under 5 and will pull 2 slalom skiers out at once(both over 190 lbs.)I did however find that these props dont work well on big block boats they cavitate.the best 800 dollars I ever put in a boat,my 4.3 runs as well as my 88 300hp 350 did.the guy I know that sells these props was so confident in them he put it on before I bought it to try.the only time it has been off is to clean it,needs to be done like a sled clutch.mercury also sells a v.p. prop called the quick silver,not as adjustable as the torque shift though.price is high but once you run one you will never go back to a fixed pitch on the smaller engine boats again.

wow...it took your boat 10 seconds to plane out? That must be a big boat, or is that when it is loaded? Ours only takes real long if there are like 4 people sitting behind the windshield or pulling two ski tubes with heavy riders. (ie me http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/wink.gif)
It just doesn't jump out of the hole like I think a 190HP engine should.

Hi Rock,
* * there are actually four routes to go, Dooman suggestion, or drop the pitch to 18 (but watch your redline v.i.p.), or decrease the size of the prop. How many inches is the prop, drop it by an inch. Will any of the marinas near you work with you on the props (if it doesn't work after a test, return for a full refund)? Some marines will have a bunch of test props for customers to try on their boat.
* *Another idea is go to a 4 blade with a 17 pitch or 18 pitch. Four blade has a better bite than three so the drop in pitch will be greater. You will lose top end in any case you take advantage of...You don't want to overload the motor though with to big a bite. Trim all the way down, you should be around 500 -800 rpm below redline, trim the motor up for optimum speed *without loosing handling should bring you on if not 100 rpm or less below redline. Mercury makes a Quicksilver SS 4 blade. I have seen better success going to a 4 blade for water skiing on older boats.
*Trim tabs, there are fixed and hydralic. Advantage: Will keep the bow down underway, can balance the boat if you have an uneven load aboard. *Disadvatage: People use them as steps, Cost to purchase and install, more holes in the transom (8 holes per tab if hydralic), Installed incorrectly (wiring backwards, holes not sealed correctly), is there room for the tabs on the transom and pump in the engine room. I have installed a bunch of these.
* * *Other thing you need to take into consideration is the Hp of the motor vs the weight of the boat. Your boat is getting old so some of the material is retaining water (any wood in the stringers, or floor may be holding water) so as time goes forth, the boat just gets heavier and the boat now becomes best for fishing not water skiing. If I remember , I will check for a prop guide at the marina and at home. When you get a chance call me on my cell, I need the total weight of your boat.
* How did you make out on the transducer?

Rob * http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/smile.gif

yes rocketman the 10.5 seconds was loaded and pulling a 220 lbs. slalom skier.I like real world info so most that I offer are real world results.the reason I went the route I did was *because I lost no top end performance actually gain more speed if I let the prop swing more, but as you know your rpms go up as well. its as simple to adjust as the tra clutch.