Engine and outdrive swap

[Bplum1987]

I have a 1984 flotebote heritage 280 with a 3.0 omc stringer the block is cracked im looking at buying a 1986 mercruiser 3.0 can I just swap engines and outdrives?

 

[Scott Danforth]

No. the stringer uses a giant hole that the outdrive passes thru. the hole is about 20" x 20" in size.

the mercruiser uses a "key hole" that the driveshaft and steering pass thru. the keyhole is about 6" by 16". to simply swap you would need to rebuild your transom.

you can, however strip all the mercruiser added stuff off the 1986 motor and strip it down to block and heads, then strip down the OMC and put the running 1986 block and heads where the busted 1984 block and heads were.

 

[Bplum1987]

Thank you scott sounds like that is what i am going to do

 

[Scott Danforth]

while at it, look at the stringer boot and separate the lower from the upper and inspect the vertical drive shafts. be careful of the shift cable on the stringer. its about $600 these days

 

[Bplum1987]

The engine blew up and the boat has been parked since 2014 what should I check on the outdrive any help and howto's will be much appreciated

 

[Scott Danforth]

at a minimum you will need a raw water pump.

check the stickies. plenty of stringer vids here: http://www.sterndrive.info/

 

[Bplum1987]

Ok so I found a 1981 omc 140 3.0 with a 400 outdrive I'm almost certain mine is a 1984 3.0 with an 800 outdrive so my question is are the motors the same and will the outdrives swap as well?

 

[Bplum1987]

I would like to run the 800 that is in the boat but keep the 400 for backup

 

[southkogs]

400 vs. 800 was effectively the designation between being used for the 4 cylinder (400) or the 6 or 8 cylinder (800). Gear ratios should be pretty different between those to two drives, so make sure you know what you have. Some ratios you can overcome with a prop ... some you can't.

The 800 hangin on your 4 banger will push the boat, but the performance may be sub-par.

 

[Bplum1987]

So maybe mine is a 400 also then pretty sure its factory

 

[southkogs]

Really, if you can figure out the gear ratios of the uppers and lowers (or overall) that's the key concern.