engine rotation on twin Inboards

No they are straight drives. No Aft Berth. All engine and tranny's down there.

However, according to the Mercruiser Service manual, page 8, Std engine rotation on all Mercuirser engines MCM sterndrives and MIE inboards, (mine is MIE) is CCW from the flywheel viewing towards the water pump. Opposite RH rotation on MIE inboard engines is Clockwise from the flywheel view.
I can see where the confusion comes in....
 
speakrdude said:
No they are straight drives. No Aft Berth. All engine and tranny's down there.

However, according to the Mercruiser Service manual, page 8, Std engine rotation on all Mercuirser engines MCM sterndrives and MIE inboards, (mine is MIE) is CCW from the flywheel viewing towards the water pump. Opposite RH rotation on MIE inboard engines is Clockwise from the flywheel view.
I can see where the confusion comes in....
Click to expand...

Jim,

I plan on going out tomorrow and when I start up I'm going down in my engine room and look at my engines while they are running and see which way they turn...I'll be able to see the input shafts ahead of the transmissions.

What the MM guy told me today makes sense that standard is starboard and clockwise at the flywheel and reverse is port and counter clockwise at the flywheel.

Meanwhile...check this out..http://www.propowermarine.com/faq-rotate.htm

I'll let you know how mine are.:thumbsup:
 
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According to the drawing you sent, All I/O engines or the standard rotation is LH or Counter Clockwise from the flywheel.

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 Left Hand, and counter-clockwise would be Right Hand. Never rely on propeller rotation to determine engine rotation. ALL I/O ENGINES ARE LEFT HAND!

. What I am getting so far from all of this is: Port (left) Engine (which is NOT the norm) should be turning Clockwise from the flywheel. The Starboard (right) engine which IS the normal or standard rotation should spin counter clockwise from the flywheel. or am I 180 degreees off?

Yes if you look at your engines that would be very usefull
 
"What I am getting so far from all of this is: Port (left) Engine (which is NOT the norm) should be turning Clockwise from the flywheel. The Starboard (right) engine which IS the normal or standard rotation should spin counter clockwise from the flywheel."

NO!!
 
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speakrdude said:
According to the drawing you sent, All I/O engines or the standard rotation is LH or Counter Clockwise from the flywheel.

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 Left Hand, and counter-clockwise would be Right Hand. Never rely on propeller rotation to determine engine rotation. ALL I/O ENGINES ARE LEFT HAND!

. What I am getting so far from all of this is: Port (left) Engine (which is NOT the norm) should be turning Clockwise from the flywheel. The Starboard (right) engine which IS the normal or standard rotation should spin counter clockwise from the flywheel. or am I 180 degreees off?

Yes if you look at your engines that would be very usefull
Click to expand...

Dude...you are 180 deg out. Look at the drawing again. The top row shows the inboard configuration from the flywheel. The starboard (right hand) is shown turning clockwise which is standard. The port (left hand) is shown as reverse rotation from the flywheel which is not standard.

On the next row down it is explained that from the front of the engine where the pullys are the rotation is reversed. In that explanation in refering to I/O stern drive motors you call left hand (CCW) RH or CW at the fly wheel because you can't get between the transom and the motor to see the fly wheel. So looking at the front or pulley end of an I/O you will always see LH rotation which will be RH or clockwise at the flywheel. As far as I know I/O's have always used the outdrive to reverse the rotation.

Here is another sketch that I found that helps explain the inboard rotation arrangement.

http://i249.photobucket.com/albums/gg221/rduhon_album/Chris%20Craft%20Engine%20Ifno/ChrisCraftRotation.jpg
 
That picture certainly makes sense. So the engine that the shop is rebuilding for me which is for the port side needs to be bass-akwards.
 
Correct. I checked mine today. The starboard engine rotates CW as seen from the rear or flywheel. The port engine turns CCW as seen from the rear or flywheel. With staight transmissions, this turns the props the same way.:thumbsup:
 
Bought a 1986 39EC last August. Owner said port engine was siezed, and sure was. After about one week of trying to get free, it ran for about 3 hrs and blew a rod. Started looking for a port motor. Found two in Joppatowne,MD, out a 1988 39EC. Found out port motor was standard rotation. My blown was counter-rotating.The engines bought were both standard, with counter port rotation happening in the transmission. DELEMA!! :huh: Girl friends' father who worked on engines and trannies for years suggested: 1) change oil pump 180 degrees 2) put starboard prop on port shaft (I had a spare set). I installed the engine with changes Labor Day weekend. Ran boat all day Monday and it Ran GREAT :smt038 Sold other engine the next week (I have some parts left over from the old engine). Boat still runsexcellent with planing a 2700 rpms
 
"put starboard prop on port shaft"

Big mistake.You can't reverse a prop for use on the other side like that. For the boat to perform as designed, the tops of the props (and therefore the shafts also) need to rotate toward their respective sides of the boats.

How you get the shafts to rotate depends again on whether you use a starboard reverse rotation motor and direct drive transmissions, or dual standard rotation engines with the output of the starboard side reversed by the transmission.
 
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In my mind I'm thinking that the boat will have a bias to starboard with this arrangement and will try to swing the stern around to starboard. :huh:
 
Sorry to chime in late here, but I just replaced a reverse rotation 5.7l Merc in my boat. The serial number itself does not show any indication of rotation but you can verify with Merc over the phone. On my model the serial number tag and the flame arrestor cover had the serial number followed by "OPP" for opposite rotation.

When I replaced the motor, the company I got a new long block from gave an easy suggestion of how to check rotation and in my case was right on the money. If the motor has a timing chain it will be standard rotation. They had us verify there was no timing chain just a gear set for the reverse rotation motor. I never noticed it before but now can hear that the reverse motor has a different sound to it and my mechanic has explained that it is the gear set in place of the timing chain.

By the way kudos to Rapido Marine Engines out of Hollywood Fl. Motor is running strong.

Dan
 
Cocktail Time said:
Sorry to chime in late here, but I just replaced a reverse rotation 5.7l Merc in my boat. The serial number itself does not show any indication of rotation but you can verify with Merc over the phone. On my model the serial number tag and the flame arrestor cover had the serial number followed by "OPP" for opposite rotation.

When I replaced the motor, the company I got a new long block from gave an easy suggestion of how to check rotation and in my case was right on the money. If the motor has a timing chain it will be standard rotation. They had us verify there was no timing chain just a gear set for the reverse rotation motor. I never noticed it before but now can hear that the reverse motor has a different sound to it and my mechanic has explained that it is the gear set in place of the timing chain.

By the way kudos to Rapido Marine Engines out of Hollywood Fl. Motor is running strong.

Dan
Click to expand...
sprink56 said:
Dude...you are 180 deg out. Look at the drawing again. The top row shows the inboard configuration from the flywheel. The starboard (right hand) is shown turning clockwise which is standard. The port (left hand) is shown as reverse rotation from the flywheel which is not standard.

On the next row down it is explained that from the front of the engine where the pullys are the rotation is reversed. In that explanation in refering to I/O stern drive motors you call left hand (CCW) RH or CW at the fly wheel because you can't get between the transom and the motor to see the fly wheel. So looking at the front or pulley end of an I/O you will always see LH rotation which will be RH or clockwise at the flywheel. As far as I know I/O's have always used the outdrive to reverse the rotation.

Here is another sketch that I found that helps explain the inboard rotation arrangement.

http://i249.photobucket.com/albums/gg221/rduhon_album/Chris Craft Engine Ifno/ChrisCraftRotation.jpg
Click to expand...
I have a pair of twin 350's with velvet drives, I recently acquired. Neither was running. I checked the engines firing order and how the wires were actually hooked to the plugs and determined the starboard engine was the reverse rotating engine, because the wires were hooked up in reverse firing order, and it runs. It runs clockwise from the flywheel end. the port engine wants to turn CCW according to the prop, but the tag on the engine has an RH on it which I understand is standard when viewing from the front of the engine. Now my confusion is with the starters because they come in from the back or drive end of the flywheel which is opposite of an auto engine so the starter must turn opposite of the auto starter. Does this mean I need a standard rotation marine starter or does it change with different drives as to what is standard?
 
I know I'm late to the party and may not have absorbed every thing, but if you have a 2002 DA, both engines should turn the same. Did I miss something?
 
A standard turning left hand motor, flywheel turning to the left or CCW uses a aft mounted starter turning clockwise. A right hand turning motor ,flywheel turns to the right CW uses a CCW turning aft mounted starter
 
wayne0 said:
I know I'm late to the party and may not have absorbed every thing, but if you have a 2002 DA, both engines should turn the same. Did I miss something?
Click to expand...
I read through all the text because I just got an older boat with twin 350's that were installed in 89 with velvet drives. They rotate opposite each other. My understanding after reading all this is that more recent setups achieved opposite rotation with their transmissions rather than reversing the engine rotation
 
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