Whole Drive Swap - Can it be done?

[rocket1968]

I have a 1976 Mercruiser 165HP Straight 6 that was rebuilt with 150 or so hours. I have access to a 1989 Wellcraft with a trashed 175 hp. Mercruiser. What are the main things I need to be aware of for a motor swap. I am assuming I will be using a boat shop hoist to get the block into place.

 

[Don S]

Re: Whole Drive Swap - Can it be done?

The exhaust Y is going to be the biggest problem. Your exhaust tube for the inline 6 will not fit on the Alpha transom shield. Not sure if the spacing for the rear mounts is the same, and I think the input shaft on the outdrive is also a different length.
Then you will find you don't have a front motor mount pad for your L6 because the 175 is a V6 with side mounts.
Then there is the shift bracket on the V6 that you will have to mount someplace.
It's not going to be an easy swap.

 

[rocket1968]

Re: Whole Drive Swap - Can it be done?

Restated: Can I swap both the drive and the engine? My concern is engine mounts, hole in back of boat, is it standard, overall performace. I am an auto mechanic and have taken on some car engine rebuilds, but they were exact swaps. I dont know the engine codes as much on Mercruisers, but I will soon figure it out. Will I get much better fuel economy with a newer engine (FI vs. carb?)

 

[Don S]

Re: Whole Drive Swap - Can it be done?

Sure you can swap the whole thing, cutout in the transom is exactly the same. You will still have to deal with a front motor mount for the inline 6 as I mentioned before.