3.0L Mercruiser with Alpha One to 4.3L Mercruiser with Alpha One Swap

MJD2

Recruit
Joined
Jul 9, 2019
Messages
1
Hello All! Question for the pro's here, I am new to the boating world so all the help I can get is much appreciated. I have a 1986 Rinker 186 with 3.0L Mercruiser with Alpha One outdrive. Motor is done, needs rebuild. I have found a nearly identical boat with a bad hull (stringers and floors rotted badly) but it has an excellent Mercruiser 4.3L and Alpha One outdrive that is an excellent deal, much cheaper then a rebuilt 3.0L. Question is, to do the swap would I swap the complete 4.3L with Alpha One over to my boat (due to gear ratio differences)? Is there anything I need to be on the lookout for? Any other parts that I would need to buy? Would the 4.3L mount differently? Thank you!
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
Have to glass in new motor mounts. Not hard, just a fun project. I did what you are proposing, it was a blast and the boat is a lot better with a 4.3 in it.

All part swap over... pretty much everything. Is the 4.3 also an Alpha 1 and not a Gen2? If they are both Alpha 1 then you can leave the entire transom assembly in place and just build in motor mounts and swap legs.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,306
unbolt the 3.0 scrap and sell what you can

migrate everything 4.3 from the helm to the prop over to the new boat

re-do the fiberglass mounts for the new motor like Rick mentions
 
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