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twin 454 engine rotation

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Old 08-15-2007, 12:29 AM
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Default twin 454 engine rotation

I am rebuilding a 1989 Donzi that has twin 454's. Unknowing I tore one of them down before checking rotation. I got a Mercruiser manual and it said that all Mercruiser engines turn the same direction the out drives is what canges the directions of the props. Is this true?
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Old 08-15-2007, 01:13 AM
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yes that is correct
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Old 08-15-2007, 01:28 AM
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thanks speedreeder
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Old 08-15-2007, 07:43 AM
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from my understanding it is the prop that makes it turn different. Is this a Z33 ? I rebuilt one of these, an 88.
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Old 08-16-2007, 12:06 PM
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Originally Posted by MitchStellin View Post
from my understanding it is the prop that makes it turn different. Is this a Z33 ? I rebuilt one of these, an 88.
Mitch c'mon, The prop makes it turn different? Interesting Physics theory. Is that like the tail wags the dog? LOL The prop spins in the direction that the shaft is turning. The gears in the outdrive change the direction of the prop shaft. Thats why you have right - hand rotation TRS drives and left hand rotation TRS drives. But you are correct, the engines both turn in the same direction. Bravo drives are a little different since they have, for lack of a better expression, built-in transmissions.
It's a common misconception that marine twin engines turn in opposite directions. Some very old-school Chryslers did it in the mid-sixties, but it was too expensive because you had special reverse rotation items like camshafts and starters.

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Old 08-16-2007, 12:13 PM
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More specifically, all Mercruiser stern drive engines are left hand motors. However Mercruiser Inboard engines come in left and right rotations.
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Old 08-16-2007, 12:17 PM
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More specifically, all Mercruiser stern drive engines are left hand motors. However Mercruiser Inboard engines come in left and right rotations.
Jim
Jim - INBOARDS???? This is Offshore - Only, not Offshore Fishing! LOL, And yes, you are correct, I was commenting on I/O's. Barry
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Old 08-16-2007, 12:22 PM
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O.C.Barry, I have known people to buy used merc engines for repower only to learn that the hard way.
Jim
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Old 08-16-2007, 12:27 PM
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O.C.Barry, I have known people to buy used merc engines for repower only to learn that the hard way.
Jim
Which isn't bad I guess if they don't mind either:

A) Boating in circles
or
B) Having one shifter face forward while the other faces rearward.

(Obviously I'm being facetious)

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Old 08-16-2007, 12:29 PM
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Barry, I'm just killing time since it's raining here. It's all good
Jim
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