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TOPIC: 120/140 Mercruiser O/D combatability w/ later 140

120/140 Mercruiser O/D combatability w/ later 140 5 years 5 months ago #71617

  • satx78247
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Friends,

Will a 1985 vintage 140HP Mercruiser engine successfully mate-up to a 1969 Model 120/140 Mercruiser outdrive?
(I know that some engine/OD combinations will not work, according to the book. - this one is a bit of a mystery to me.)

IF this is NOT a straight change-out, can it be made to work W/O a great deal machine work, by using only the long-block from the 1985 engine and the exterior parts off the 1969 120HP Mercruiser engine????

BOTH the engine and outdrive, though of 16 years difference in model year, are BOTH in good shape, separately.
(The engine that is currently in the 1969 model 19ft SternCraft Bowrider is decidedly NOT REPAIRABLE.)

THANKS.

yours, satx

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Resistance to tyrants is obedience to Almighty God.
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Re:120/140 Mercruiser O/D combatability w/ later 140 5 years 5 months ago #71628

If the '69 is a 140 & the manifolds look the same, yes they will bolt in.

If the '69 is a 120 and the manifolds look similar, then they will bolt in but I believe you will need to swap out the lower exhaust collector pipe that goes from the rubber coupler down to the inner transom plate.

By the same or similar, I mean that they are of similar design and the riser are squarish and go straight back, not rounded or go off at an angle like the later years. I think 1985 will still be OK.

The 120 & 140 manifolds were not the same between the two even in the same years. A 120 manifold will suffocate a 140 engine.

Jim

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Re:120/140 Mercruiser O/D combatability w/ later 140 5 years 5 months ago #71630

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jimandros,

I see that I wasn't clear, after re-reading my post above. - Let me clear up what i should have said. = the UN-REPAIRABLE engine (the PO's son ran the 120 out of the water and RUINED it.) that is IN the boat is a 120HP Mercruiser.
the engine that i've found, as a POSSIBLE replacement for the 120HP, is a 140HP 1985 model Mercruiser and runs fine - it has few hours on it.

As the 1969 OD on the boat is a 120/140 unit and is in good shape, what i'm wondering is if it will bolt-up to the 1985 engine, without spending a goodly pile of bucks trying to make it work.

SORRY for the confusion.

yours, satx

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Re:120/140 Mercruiser O/D combatability w/ later 140 5 years 5 months ago #71680

The outdrives are interchangeable. Just be certain that the length of the driveshaft into the engine is the same. The inlines used a shorter version until the mid 80s but I believe you will be OK. If not, you will need to remove one u joint & swap the drive shaft.

The real issue is if the 140 will bolt into the boat assuming you are using the 1969 transom plate & exhaust collector. That was what my earlier answer was pertaining to.

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Re:120/140 Mercruiser O/D combatability w/ later 140 5 years 5 months ago #71751

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THANKS, jim!

yours, satx

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