3.0 to a 4.3 swap?

[OLDFISHER]

Greetings, I just bought a really clean 20' Bayliner Trophy 2059 with a locked up 3.0 and alpha out drive. I have priced short and long blocks and got to thinking??? I do have a 4.3 close to fresh in a 1990 bowrider out back is this a possible engine swap? the alpha out drives are both good. Can I get some experienced input please? Thanks

 

[Scott Danforth]

first, is the bayliner rotten?

IF and only IF there is no rot on the bayliner, cut out the front mount for the 3.0, glass in new motor mounts for the 4.3, gel coat as required, then bolt-in, align motor, install drive and go boating. should be a weekend job

 

[Bondo]

with a locked up 3.0 and alpha out drive.

Ayuh,.... Welcome Aboard,... Have ya pulled the drive off the 3.0l,..??

It turns with the crank shaft, so if ya haven't, you still don't know whether ya need a motor, or drive,...

Also, if ya do the swap, the drives are different ratios, meanin' they're not interchangeable,...

 

[Scott06]

https://mercurymarine-gsdesign1.netd..._1996-2001.pdf

3.0 engine drawing

https://mercurymarine-gsdesign1.netd..._1996-2001.pdf

4.3 drawing

good comments above, 3.0 more mounts up front , and the 4.3 on either side of the block. If you're lucky the side mounts are in your boat, if not you gotta build them as Scott pointed out. If you have to build them, @RickStephens has posted nice photos of the same swap in his boat.

 

[Rick Stephens]

Thanks for the heads up Scott.

OldFisher, indeed, last winter I installed a 4.3L and the appropriate geared outdrive in my 3.0L boat. Have to admit I had a great time going through everything, and I mean complete engine rebuild and outdrive reseal along with the mounts and transom rebuild, before I finished. The bonus, I know a lot more about my engine and drive than I would have otherwise.

Not a technically hard project if you like measuring, installing, removing and measuring again. Be prepared to find what you find when you start drilling for water damage.

Rick

 

[OLDFISHER]

Thanks to all, with out starting the task I know these posts are what I was looking for. Bondo, I hope I am that lucky, that will be my first move. Thanks all again.

 

[OLDFISHER]

No leg lock issues....bummer, so I guess its engine pull time.