convert an 85 to a 140?

billgrob said:

i have a 76 johnson 85hp short shaft that runs great but im wondering what would be involved in powering it up to a 140hp. i have a guy looking to sell me the carbs and exhaust manifold off a 140. do i just throw in some high compression pistons with the carbs and manifold?

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kenmyfam said:

Best way is to
1. Remove the 85hp from the transom of the boat
2. Sell the 85hp
3. Scan the classifieds for a 140hp with controls
4. Fit the 140hp to the transom and hook up the controls.

This is assuming that the boat can handle and is rated for a 140 hp.

It's that easy.
My 2 cents.

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Dhadley said:

We'll assume you want to convert an 85 crossflow to a 140 crossflow, not a 140 looper. If you want to end up with the power of a 140 looper, it ain't gonna happen.

Actually it's very possible. Not practical but possible. If I remember correctly the small bore 85 doesn't have enough meat to be bored to 3.500" so you'd have to resleeve all 4 and use the 140 style port timing. Then find some late model heads.

You'll still be stuck with the old style intake. (There is a way around that but it gets very involved) You'll also be stuck with the old style gearcase.

In the end you'll be very disapointed.

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