Whch engine is auto rotation and which is reverse??

Whch engine is auto rotation and which is reverse??

Joined: August 30th, 2006, 10:15 pm

September 7th, 2006, 3:05 pm #1

In a twin engine Chris Craft, which engine is the correct automotive rotation and which engine is the reverse of an automotive aplication?

Is the Starboard engine the one that is backwards from an automotive application or is the port engine the backwards one?
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Paul
Paul

September 7th, 2006, 6:06 pm #2

.....when viewing the flywheel.

Now this gets interesting with a flywheel forward motor installation!

I have a LH (standard automotive) couterclockwise rotationg small block Chevy motor in my 1956 Chris Craft Sportsman, but I am running a RH prop because the motor is flywheel forward and the transmission is running off the front of the motor opposite the flywheel.

If you have any doubt, go take a look under the hood of a motor that uses a belt driven fan (in a traditiional rear wheel drive application), you'll see the fan direction is pulling air toward the motor, and the blades give the story that they are turning counterclockwise in order to do this, when looking from the drivers seat.

Bottom line:

LH is standard counterclockwise automotive rotation (when looking at the flywheel)

RH is considered clockwise "opposite rotation" (when looking at the flywheel)


Regards, Paul
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Paul
Paul

September 7th, 2006, 6:13 pm #3

On the standard rotation engines (those LH engines running clockwise when viewed from the flywheel, same direction as those used in automobiles) you'll notice the firing order is cast into the intake manifold.

On the opposite hand rotation engines (RH clockwise rotation, when viewed from the flywheel) you'll notice someone has taken a grinder to that intake manifold!! That "someone" was an individual at the Ford engine plant, or the Chris Craft engine plant. They actually use the same intake manifold, but obviously they can't use the same firing order if one is LH and the other is RH, so they just took a grinder to the opposite (RH) rotation motors to be sure nobody would try to wire up the motor wrong. It's possible that during a rebuild or parts swap, that the wrong manifold got placed on the wrong motor, and it will work just fine as long as you stick with the required firing order!

Paul
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Joined: August 30th, 2006, 10:15 pm

September 8th, 2006, 5:39 am #4

In a typical Chris Craft boat with twin engines, which motor is the LH rotation and which is the RH rotation engine? The starboard engine is RH?? The Port engine is RH??
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Joined: November 8th, 2005, 10:54 pm

September 8th, 2006, 5:43 am #5

Normally the starboard motor is the reverse rotation motor the port motor is "normal"
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Paul
Paul

September 8th, 2006, 2:18 pm #6

In a typical Chris Craft boat with twin engines, which motor is the LH rotation and which is the RH rotation engine? The starboard engine is RH?? The Port engine is RH??



Logic would suggest that all single motor installations would default to the standard automobile rotation, since most boat motors are derived from automobiles. However, this doesn't appear to be the situation at CC.

Regards, Paul










Last edited by FEfinaticP on July 9th, 2009, 2:16 pm, edited 1 time in total.
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craig
craig

September 13th, 2006, 3:08 pm #7

Or at Century...
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Tom Slayton
Tom Slayton

September 13th, 2006, 3:32 pm #8

I'm very curious why the marine industry apparently uses an opposite rotation motor for their applications when it's a single motor. It would appear they would be able to source motors at much lower cost by using the standard rotation same as the auto industry does. Apparently nobody there heard of the KISS (keep it simple, stupid) concept? Are there any rules of physics that make one better than the other in a single motor applicatiion??????

Question of the day!

Tom
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Greg Mason
Greg Mason

September 14th, 2006, 3:06 am #9

Hello fellow Commander lovers!

I will venture a guess on this one. It has to do with the effects of rotational torque on the boat when the driver gives the engine full throttle. If the helm is on the right side of the boat and the driver is the only one in the boat, hence no other weight from other people, when sudden full power is applied the boat will torque or twist counter clockwise. This would have a tendency to lift the right side of the boat which is where the driver is sitting, therefore keeping the boat more balanced under full throttle. If the boat was running a standard/left hand rotation engine and left hand prop it would twist/rotate clockwise, throw the boat out of balance because of the drivers weight on the starboard side. The boat would have a great tendency to list starboard under load. Does this make sense? Maybe only in the crazy world I live in.

Car engines turn left hand, twisting the body to the right and lift the drivers side up. Watch drag cars twist and you can really see it. But what about cars with the drivers seat on the right? Oh well, I'm really confused now. LOL

BTW, absolutely a great web site Paul. I've been reading for months and really enjoy it. Thank you!

Greg Mason
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Paul
Paul

September 14th, 2006, 10:52 pm #10

Welcome aboard, please feel free to post questions, comments, and/or photos. Thanks for the good words too!

As for your logic, I would agree with the previous post that it would appear to be worthwhile to adapt to the standard automotive rotation, than to go with custom rotation on single applications. Since I've seen runabouts with the helm on the port and starboard, it seems to make little difference which side the captain is sitting on. Oh well, what appears logical often proves to be a proverbial can of worms. Regards, all the best,

Paul
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