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Repowering an 89 Chris Craft Scorpion

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mechanix565

New member
hey guys im new to boating but have been building hotrods for about 10 years so i have plenty of mechanical knowledge but im a little green on some of the fundamentals of boat drivetrains. also im not sure if im posting this in the right section forgive me if im not.

what i have is a 1989 Chris Craft Scorpion 190 (18.5 feet) the boat was produced with a Mercruiser 3.0v6 well the motor and drive are long since gone and i aquired the boat without either, what i do have is a 1989 fourwinns bow rider with a good merc 350 and alpha 1 drive the fourwinns is complete with everything but has a bad hull (hit a rock)

what do i need to do to get that merc 350 into the Chris craft, what needs tobe done with the motor mounts etc... i really like the idea of putting the v8 in the chris craft because its a reman merc 350 with 350hp so it should go pretty good and be very responsive. just not sure what needs to be done to get it in there. the boat came with an alpha 1 drive originally so im going to go off on a limb and guess that all the hydraulics will bolt right up for the drive and it was a gm motor originally so the power steeriing will also bolt right up. let me know guys im diving into this project head first and i wanna get this old girl back in the water soon.
 
Before going any further, check the manufacturer's plate on the boat and see what the maximum horsepower rating is. I usupect it is less than 350. If so, I would not atempt doing what you plan to do. Besides, in most states it is illegal to exceed the max power rating on a boat, and it will not be insurable. If max HP is 350 or better, your next concern is weight and weight distribution. Determine how much more weight is being added with the 350 and Alpha drive. If it is more than two hundred or so pounds, you may experience serious performance problems because it will be difficult to get the boat to plane and ride properly.

Check out the Chris Craft forum on I boats and post your questions there. http://forums.iboats.com/Boats/Chris-Craft
 
Thanks for the reply the Max hp is 350 and the boat was optioned with an omc 5.7 with a cobra outdrive so I don't think weight will be a problem
 
Okay - that works. I'd go to the Chris Craft Forum on iboates.com to discuss lining up the mounts. Just some things to consider before mounting the 350.

1. If it does not already have one, install an aluminum or SS oil pan. The stock oil pans tend to rust out, especially in a saltwater environment.
2. If there is room, fit a heavy duty drain hose in the oil pan's drain plug that will allow you to completely drain the motor oil with the engine installed. I did this on a Crusader 220, and coiled up the drain hose in the bilge. When it was time for an oil change, I simply s***** the hose through the bilge drain, opened up the cap, and had a really fast, clean oil change. That is a far better method then trying to suck the oil out of the dipstick hole or the filler opening, and it get all of the old oil out.
3. Set it up with a closed cooling system - that is one with a heat exchanger tank. That will do more for the longevity of the engine than about anything else you can do, and it makes winterizing a snap..
4. If there is any doubt about the headers and risers, replace them. It's a heck of alot easier to do while the engine is out of the boat.
5. Install new bellows on the outdrive and double clamp them if there is enough room.
6. Inspect your freeze plugs very closely for leaks or signs of corrosion. Replace them if there is any suspicion at all.
7. If there is any question about your water pump on the 350, change it while the engine is out of the boat. They are a complete pain in the a** to change once installed.
8. Carefully inspect your valve cover seals for any leaks. If any, change them.

Hope this helps.
 
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