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Old 09-06-2013, 08:29 AM   #1
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engine rotation

I have a trawler with 2 perkins 354s

which one rotates normal and which one reverse

(im new to twin engines sorry if its a silly question
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Old 09-06-2013, 09:25 AM   #2
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In many twin set ups the engines are identical and the props are reversed and the rotation change is in the transmission gear. Start the engines and look at the engine rotation. Put them in gear and look at the shaft rotation. You will get the picture.
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Old 09-06-2013, 09:31 AM   #3
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Remember that the rotation, whether or not it's clockwise or anti-clockwise, is noted by viewing from the REAR of the engine looking forward.

I have a single Perkins 6.354 that is anti-clockwise. Which to me, seems weird.
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Old 09-06-2013, 09:57 AM   #4
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Didn't know that Tom.
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Old 09-06-2013, 11:55 AM   #5
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I have a single Perkins 6.354 that is anti-clockwise. Which to me, seems weird.
Not at all weird. "It's left handed" and I'll bet that most single engines on this Forum are the same. Mine is!

Your boat backs to starboard?
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Old 09-06-2013, 12:00 PM   #6
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Mine's left-handed too.
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Old 09-06-2013, 01:05 PM   #7
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Marine Engine rotation is viewed from the flywheel end of the engine, clockwise would be a Right Hand Engine, and counter-clockwise would be Left Hand Engine. Since you usually cannot see the flywheel with the engine in the boat it can also be determined from the front of the engine. If you are looking at the front of the engine at the belts and pulleys, Clockwise would be a Left Hand Engine, and Counter-clockwise would be Right Hand Engine. A Standard Marine Engine is a Left Hand 'Engine. A Reverse Rotation Engine is a Right Hand Engine. Never rely on propeller rotation to determine engine rotation. Most conventionally-mounted single Inboard Engines are Left Hand Engines. I'm pretty sure all I/O engines are Left Hand Engines.

I think some confusion arises when discussing engine rotation because by and large, in the automotive and industrial engine world, engine rotation is generally referred to as Clockwise or Counter-clockwise when viewed from the front (pulley and accessory) end, not the flywheel or drive end. Most Standard/Normal Engines rotate Clockwise when viewed from the F
ront. I suppose that in this context, someone might say that a Clockwise engine turns to the Right, but that does not make it a "Right Hand Engine."

If you open the hood of most cars or trucks and look at the pulley and accessory end of the engine, the rotation will be Clockwise. That is Standard or Normal engine rotation. That same engine when installed in a boat will be called
a Left Hand Engine which is a Standard Marine Engine.

Hell, now I'm confused

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Old 09-06-2013, 01:33 PM   #8
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Unless there is a twin set up, my guess is that Lehmans are left handed, or as I look at it, we dock to starboard because in reverse that is the way the boat pulls. (Ignoring my wing engine which purposely pulls to port.)

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Old 09-06-2013, 01:38 PM   #9
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You guys are not staying focused. The thread starter asked which of his two engines rotates normal and which rotates the reverse? I do not have Perkins 354s so I do not know. But I would like to know.
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Old 09-06-2013, 02:05 PM   #10
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Quote:
Originally Posted by davesail View Post
I have a trawler with 2 perkins 354s

which one rotates normal and which one reverse

(im new to twin engines sorry if its a silly question
Dave I own a single so take this with a grain of salt but have been told by many who should know that most twin engines rotate the same direction. The rotation reversal for the prop shaft normally happens in the marine gear (transmission). Hope this helps.
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Old 09-06-2013, 02:12 PM   #11
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There is an echo in the room. That was my answer.
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Old 09-06-2013, 02:40 PM   #12
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Quote:
Originally Posted by davesail View Post
I have a trawler with 2 perkins 354s

which one rotates normal and which one reverse

(im new to twin engines sorry if its a silly question
Davesail,

Typically, when viewed from the rear of the boat:

The Port engine should be a "Left Hand Engine" and the flywheel should rotate Counter-clockwise. This is the "Normal" engine.

The Starboard engine should be a "Right Hand Engine" and the flywheel should rotate Clockwise. This is the "Reverse" engine.



You can also confirm this by finding the engine identification code. Perkins "Right Hand Engines" are identified by the letter "X" stamped immediately after the manufacturing location code letter (e.g. 354UX252T). The first three numbers are the cubic inch size, the next character is the manufacturing location. The "X" will be the next character if the engine is "Reverse Rotation". This identification is located on the Fuel Injection Pump Mounting Flange on the Left Side of the Engine.

Hope this helps.

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Old 09-06-2013, 03:30 PM   #13
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There is an echo in the room. That was my answer.
Oops. Read no further than the OP on my iPhone. Shoulda read the rest of the thread first
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Old 09-06-2013, 03:31 PM   #14
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most all engines today are left handed,years ago they had left and right engines by changing the camshaft,so that the props swung outboard, years ago chris craft used to turn one engine around the othe way and drive the tranny off othe front of the engine, when they changed the cam they also reversed the firing order,had right hand starters , anmd a lot of other things,now days they turn the direction of the props with the tranny,in velvet drives the switch the pump around so it goes the other way worked on many of them many years ago.
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Old 09-06-2013, 04:03 PM   #15
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My "ex" a 78 Mainship 34 came originally with a "anti-clockwise" or backwards rotation Perkins (T6.354). Some parts like the coolant circulation pump were obsolete, some others were a pia to source unless the distributor had the manual for the backwards engine.
That was one of the reasons I repowered.
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Old 09-06-2013, 04:48 PM   #16
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Capt Jerry, you triggered a memory I had long forgot. I remember those motors well. Crusader also did this by using timing "gears" on one engine and timing "chain" on the other. The firing order, distributor and timing were reverse of each other. I remember many years ago doing a full tuneup and setting the timing on both engines one day. Following the tuneup I was pleased with myself because they ran smooth as silk when tested (idling) at the dock. Next day during sea trial I found my port engine would bog out when applying any throttle and for the next two days I tore the engine apart looking for the problem. Embarrassingly after much hair pulling I found I had set the timing on both to 10 deg BTDC and of course the Port should have been ATDC. (maybe vice-versa I forget). I am still amazed at how well it ran at idle being so far out of time.

Sorry Davesail for transgressing slightly off topic.
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Old 09-06-2013, 06:24 PM   #17
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Quote:
Originally Posted by LarryM View Post

Davesail,

Typically, when viewed from the rear of the boat:

The Port engine should be a "Left Hand Engine" and the flywheel should rotate Counter-clockwise. This is the "Normal" engine.

The Starboard engine should be a "Right Hand Engine" and the flywheel should rotate Clockwise. This is the "Reverse" engine.

You can also confirm this by finding the engine identification code. Perkins "Right Hand Engines" are identified by the letter "X" stamped immediately after the manufacturing location code letter (e.g. 354UX252T). The first three numbers are the cubic inch size, the next character is the manufacturing location. The "X" will be the next character if the engine is "Reverse Rotation". This identification is located on the Fuel Injection Pump Mounting Flange on the Left Side of the Engine.

Hope this helps.

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This^^

My twin Perkins rotate as described. 6.354 NA
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Old 09-06-2013, 10:56 PM   #18
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Hell, now I'm confused
Uh....thanks, Larry....that really clears it up. =================== =======>
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Old 09-06-2013, 11:30 PM   #19
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Uh....thanks, Larry....that really clears it up. =================== =======>

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Old 09-07-2013, 12:20 AM   #20
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Take a good look the next time your boat is hoisted.

Here is my left-handed, counter-clockwise, prop-walk-to-starboard propeller:

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