RE; need some thoughts on re powering a 4 cylinder mercruiser

[al1026]

Time has come too re: power
​1984 ​Sea Ray - walk around
​Sea Ray known for cruiser type boats, my model is considered a limited production
​Talking with a Sea Ray salesman at local dealer he remembered my model . He said that was a great boat.
​He said it was made few years . Size was . 21 -26 ft -
Called Fishman Model styled similar too a Boston whaler
​walk around - cuddy cabin - great day fishing boat. - tows easy - easy too get too engine for repairs - gas tank easily opens on floor . Simple boat
​My model came with the 488 Mercruiser 3.7 - self contained cooling - 4 barrel carb - 180 HP

ALPHA 1 recently rebuilt

Bracket with outboard is out of my ability and will cost too much

​488 is a bit underpowered - manifold & risers cost more then a rebuild , carb shot therefore I am considering finding a good used drop & go 6 cylinder
​What engine can I use my ALPHA 1
Other then engine mounts and prop change what else must I consider

​I have found a number of 4 cylinder engines but every one is old , all have issues . Plenty of 6 cylinder

Thanks for your thoughts
​

 

[harleyman1975]

I would go with a 4.3 v-6 try to find a newer model and have it freshened up so you are not doing this again in 3-5 years.

 

[Rick Stephens]

4.3L is probably way to go. But not all that much difference between a 4.3 and 5.0L V8 in raw HP - the V8 has a lot more torque. If you can find a donor boat with either you'd be living the life. Propping the 4.3L would be just about the same as your 3.7L. IMHO you would not have a problem propping up to run the 5.0L. A 5.0L V8 would normally connect to a 1:1.64 ratio drive. Your 470 is connected to a 1:1.84 most likely. With that big of a boat I bet you're running something like a 17 inch prop now. That leaves a ton of room to prop up for a higher torque engine like the 5.0L.

The way to do this is find a good donor boat. That way you start out with all the right parts and can bring it up to 100% without starting from scratch. Redoing motor mounts is not all that tough.

Sounds like a fun project.

Rick

 

[Scott Danforth]

21 to 26' is small block V8 territory. you could lumber along with a V6

 

[Bondo]

Ayuh,.... If the motor box is wide enough, the 4.3l is the logical swap, as all but the exhaust pipe, 'n motor mounts, works, as is,....
'n you can pick up 'bout 40 hp pretty easily,...

If yer willin' to throw in another outdrive, the 350 is the choice that makes the most sense,...