Direction of Crank Rotation

[Craig R]

I recall that the cranks some V-71's & V-92's rotate clockwise while those of others rotate counter-clockwise.
Could somebody quickly school me regarding which is found where?
Old MCI engines spin which way?
Old dogs mounted transverse spin which way?
Dump truck and COE engines spin which way?
The twin diesels pushing power boats spin which way?
Thanks. Craig

[thomasinnv]

I do believe the only ones that spin backward (lefty) are the GM transverse engines (sidewinders), and some marine engines from a dual engine setup. MCI's, Eagles, Prevosts etc. are all right hand turning engines.

[wildbob24]

Craig,

MCIs are right handers(clockwise)

Transverse GMs are left handers(counter clockwise)

Dump trucks and COEs will be right handers

Not completely sure about twin-engined boats, but I believe they use one of each.

Bob

[luvrbus]

Boat are right handed engines they reverse through a gear box

[lostagain]

Clockwise rotation is looking at it from behind the bus. Or from the front of a truck.

What can get confusing is that the DD service manual looks at things from the back (flywheel end) of the engine. Spins counter-clockwise at that end.

JC

[thomasinnv]

Boat are right handed engines they reverse through a gear box

Clifford I thought some of the older twin screw setups had one turning each direction? I know I've seen a few backward turning marine engines on the Ebay.

EDIT: On second thought, you know people often refer to a GM backward rotating engine as a left handed rotation, when they are actually a right hand rotation as seen from the flywheel side. Like JC pointed out the rotation is determined from the flywheel side...thus a MCI, Provost, Eagle and all OTR trucks would be a left hand rotation. GM transverse engines would be right hand rotation.

I did some googling and found some information saying that marine engines can be found in a right hand or left hand rotation, but then I also found some information that said all I/O engines are left hand rotation only, period. What's a guy to do if he can't trust the internet? LOL.

[luvrbus]

Some of the old marine stuff were but all the modern and some of the older stuff stuff runs through a gear box for direction fwiw the twins and the quad engines where left and right running engines into 1 common box and 1 output shaft

[Don4107]

Not Detroit but my boat with small block Chevys has a counter rotating engine.  They do it by gear driving the cam shaft so it turns normal direction or opposite the crankshaft. That keeps the distributor and oil pump turning the normal direction.   Starter, water pump, crankshaft seals, camshaft are special.  The velvet drive trans will work either way if memory serves by reclocking the input cover.

[TomC]

Any of the 2 stroke Detroits could be reversed for twin engine application on a boat.  Most engines now are not reversible-hence the opposite rotation is done at the transmission.

Sort of interesting-a few years ago I was on a 90ft crew boat converted to a live aboard dive boat that had 3-12V-71TTA's that all turned the same direction, and used 3 bladed props instead of 4 bladed.  It was very smooth.

Good Luck, TomC

[Lee Bradley]

Some of the old ferries in the Washington State fleet had direct drive; engine to propeller. Shut the engine down at the dock and start it in the opposite rotation for the return trip.