swap 2.5 omc with 3.0 mercruiser

[james hayden]

i have a 1985 harris kayot pontoon 24' with a 2.5 omc engine i also have a bayliner 19.5 with 3.0 mercruiser i want to put the 3.0 mercruiser in the pontoon will the 3.0 drop right in with no problems or do i have to swap out the outdrives too

 

[Scott Danforth]

first, welcome aboard

is your 1985 a left over 1984 stringer or a cobra unit? by 1985, OMC was only using the 3.0. they have 140 on the valve cover

what year is the 3.0 from the mercruiser? if the 3.0 is 1990 or older, you can strip off the manifold and plumbing off the "mercruiser" down to the base GM motor and replace the motor.

if the 3.0 mercruiser is 1991 or later and your pontoon has a cobra. you should swap out the longtail (motor and drive)

if your pontoon has a left over stringer, you can not use a 1991 or newer motor as there is no OMC spline coupler for the stringer drive and 1-piece RMS cranks. you can not easily swap drives either without rebuilding the transom and closing in that giant hole in it and putting in the much-smaller keyhole for a mercruiser

 

[james hayden]

first, welcome aboard

is your 1985 a left over 1984 stringer or a cobra unit? by 1985, OMC was only using the 3.0. they have 140 on the valve cover

what year is the 3.0 from the mercruiser? if the 3.0 is 1990 or older, you can strip off the manifold and plumbing off the "mercruiser" down to the base GM motor and replace the motor.

if the 3.0 mercruiser is 1991 or later and your pontoon has a cobra. you should swap out the longtail (motor and drive)

if your pontoon has a left over stringer, you can not use a 1991 or newer motor as there is no OMC spline coupler for the stringer drive and 1-piece RMS cranks. you can not easily swap drives either without rebuilding the transom and closing in that giant hole in it and putting in the much-smaller keyhole for a mercruiser

is there a place where i can look up weather i have a stringer or a cobra the omc drive model number j375061 on the tag on the outdrive itself and my mercruiser is a 1995 and what do you mean by you should swap out the longtail (motor and drive) thank you for you're time

 

[Scott Danforth]

post a pic

however if you have a big boot around the drive at the transom, you have a stringer 400

here is a pic of the boot on ebay

 

[Scott Danforth]

is there a place where i can look up weather i have a stringer or a cobra the omc drive model number j375061 on the tag on the outdrive itself and my mercruiser is a 1995 and what do you mean by you should swap out the longtail (motor and drive) thank you for you're time

your 1995 motor will not work with a stringer 400 unless you get a custom made splined coupling disk. you can take the existing disk to a machine shop and have them weld up the holes and drill new holes .

if you have a cobra drive (looks similar to the mercruiser drive). you can swap your 1995 motor AND transom shield AND drive (complete longtail - pulley to prop) in place. you will need to drill 2 holes

 

[james hayden]

your 1995 motor will not work with a stringer 400 unless you get a custom made splined coupling disk. you can take the existing disk to a machine shop and have them weld up the holes and drill new holes .

if you have a cobra drive (looks similar to the mercruiser drive). you can swap your 1995 motor AND transom shield AND drive (complete longtail - pulley to prop) in place. you will need to drill 2 holes

will the bellhousing from the stringer bolt up to the 1995 3.0 if i do take the existing disk to a machine shop and have them weld up the holes and drill new holes

 

[Scott Danforth]

Yes, the housing will bolt on. However will will to source a 153 tooth flywheel for the 1995 3.0 motor

If it was me, I would redo the transom and switch to the Mercruiser stuff