4.3 to a 5.7 in a '88 Sea ray seville

[bradt041]

Ok, so the 4.3 Merc in my 20' 88 sea ray seville is pretty much junk.. So I'm considering a long block 5.7 from Jasper.. I'm sure this motor swap has been done a thousand times and just looking for some tips... I know the exhaust manifolds and intake will not work.. I have read that you have to move the motor mounts forward to allow the room of the extra 2 cylinders, does this mean drilling new holes in the hull? Lets talk transom... I have the Alpha one outdrive.. Will I need to do anything to the gears/prop to accommodate the extra ponies? Has the 3 blade stainless on her now. Thanks alot

 

[TilliamWe]

Re: 4.3 to a 5.7 in a '88 Sea ray seville

Moving the motor mounts is easy. The "block" where they are currently screwed in, should be long enough to allow you to unscrew them, and rescrew them where you need them.
You fuel tank will probably be in the way. At least my dad's was, when he put the 5.7 in his 19' Seville. He eventually bought a new fuel tank to allow the clearance for the front of the engine accessories. it cost real money, though.
Your engine cover will probably hit the water pump pulley, so get ready to move it a little.
My dad made the V6 Y-Pipe work, but did have some issues with hose fitment. Can't remember why exactly, though.
He had a 1.81 ratio drive, and he was able to reuse it, just with a 25p prop. Now his 5.7 that he installed was no modern Vortec motor. It was a 1987 5.7, that with the cam and carb he used, probably was close to 225hp. If you install a Vortec engine that's making a lot of HP, you should probably change the outsrive. For $1195, you can get a complete Alpha One replacement from SEI. So I would not mess around with paying someone to change gear sets.
Your best course is to find a complete take out 5.7 off e-bay or somewhere. Yeah I know they are $$$, but you are going to have to buy all exhaust the stuff to fit a 5.7, and the intake, so you may spend $$$ buying it piece meal any way.

Be prepared, the boat will still not be fast. You will not have a 60mph boat when you are done. The hull just isn't a high speed hull.

 

[bradt041]

Re: 4.3 to a 5.7 in a '88 Sea ray seville

The fuel tank sits down in a cradle, would I have to cut some fiberglass out of it also? Doesn't seem right

 

[rbh]

Re: 4.3 to a 5.7 in a '88 Sea ray seville

"measure twice, cut once"
rob

 

[Bondo]

Re: 4.3 to a 5.7 in a '88 Sea ray seville

So I'm considering a long block 5.7 from Jasper

Ayuh,... A Long Block is a Long Ways from a Running motor,....
The Missing parts will cost you as much or More than the Long Block...