Reversing Engine Rotation?

Hi All
I hate absolutes!
My main purpose for posting on this site is to gather information for myself or give out relevant information, which allows people to determine the right solution for themselves

Since 79nautique made his comments, I have done some research.

Borg Warner refers to Engine Rotation in the way I describe.

The Chrysler Marine Manual, which is also available from this site refer to Engine Rotation the way I describe it. ( Page 59 & 60 if any one is interested )
Yes I have a Chrysler 383 V8 in my boat.

Yet if you look up Marine Engine Rotation on the Internet Some Manuals describe it the way 79nautique describes it looking at the Fly Wheel.
The Fly wheel Rotation is a bit hard to determine when the Bell housing and the Gearbox is attached to the Engine and installed in the boat.
Unless they have a View point on the Bell Housing
They say to look the front or forward end of the Motor.
This is also mentioned by the Marine Engine Manuals that 79nautique describe.

As I said Earlier my main point of my posts.

Prop Rotation cannot be changed by reindexing hydraulic pump on the front of the gearbox.

I just want people to get it right the first time, by understanding the concept.

However you look at it, this is how it is, 79nautique please comment if you disagree.?

Looking a the boat from the Stern to the bow of the Boat.
LH prop
Gearbox pump indexed RH or -->
Fly Wheel LH or CCW.

RH prop
Gearbox pump indexed LH or -->
Fly Wheel RH or CW.
---------------------------------------------
Looking at the boat from the bow to the stern of the Boat.
LH prop
Gearbox pump indexed RH or -->
Harmonic Balancer RH or CW.

RH prop
Gearbox pump indexed LH or <--
Harmonic Balancer LH or CCW.

Regards
Rob McDonald






Prop Rotation cannot be changed by reindexing hydraulic pump on the front of the gearbox.

79nautique wrote: rmcdonald wrote: Engine Rotation: This is determined by looking at the front of the Engine as in the Water pump. Clock Wise is CW or RH Counter Clock Wise is CCW or LH. this is completely wrong and ass backwards. long story short if you own a correct craft and it has a 1:1 transmission then you have a reverse rotation engine RH from the factory, If it's an older model with an I/O or you have a 1.23:1 transmission then it's conventional rotation LH or automotive rotation.

I agree with '79, except he forgot to mention that the Nautiques with 454's were conventional LH engines mated to 1:1 trannies and turned LH props

RH = CCW reverse rotation

LH = CW standard rotation.

BW tranny is always index opposite of engine's rotation.

it isn't CC's terminology it's the marine industries terms. You can get about any brand marine engine in standard or reverse rotation just go look at a big cruieser with duel engines.

I hope Andrews question has been answered.

It certainly appears to me that if he is purchasing a reverse rotation engine , then he should not need to change anything with the tranny(considering a RH prop was on the shaft).

rmcdonald wrote: Engine Rotation: This is determined by looking at the front of the Engine as in the Water pump. Clock Wise is CW or RH Counter Clock Wise is CCW or LH.

this is completely wrong and ass backwards.

long story short if you own a correct craft and it has a 1:1 transmission then you have a reverse rotation engine RH from the factory,

If it's an older model with an I/O or you have a 1.23:1 transmission then it's conventional rotation LH or automotive rotation.

I am hopelessly confused. How do you download the manuals in the reference section? Maybe a picture will help. I have been able to view/print the brochures, but have not been able to view the manuals. Thanks, Jerry

just look at your car motor and see which way it turns. They are almost all left handed right?

well I have to disagree and agree(at least from the perspective of what I am reading and what my engines do)...I have two complete manufacturers shop manuals...for my 312 and the 302/351.

Both manuals state that the rotation is engine determined by looking from the back of the engine(stern) .

So...looking from the back ,a reverse rotation engine spins to the right (CW) and does use a rh prop, standard rotation engines turn left(CCW) and use a LH prop.

Hope that adds to the Making sense part

According to the shop manuals I have...rotation is determined by looking from the stern...Rev Rotation or right hand turns to the right when standing behind the boat.CCW if looking front the front(at the belts etc).

Now I don't know about the tranny switching the rotation....het now I am confused too!

You guys are getting me confused (sometimes that’s not hard to do).   All right, looking at the engine from the front of the engine (belts, alternator, water pump) toward the stern of the boat, counter clockwise rotation is “left hand” rotation – am I straight here? Then looking at the stern of the boat clockwise rotation of the prop is “right handed” prop??? I do not know, I am asking. I understand that my ’89 Fish Nautique 351 has a “left hand” rotation engine, but is turning a “right handed” prop, if so what is the significance? I am going to look at this stuff tomorrow. Have a great weekend,   Jerry

Thanks again for everyones help. I am going to post some updates this evening on the boat.

Hi Andrew

Don't want to get into a debate about which rotation is correct for you boat, but to answer you original question.

To change the rotation of that engine, you would need to buy a starter motor that runs in the oposite direction, new cam that has the lobes ground in the correct way and pretty sure you will require a some modifications.

Here is another option that you have.
Buy a prop that rotates in the new direction
Index the pump on the front of the Velvet Drive
To work in the new direction of the engine.
To index the pump for oposite direction is well documented in the Velvet drive manual in the Refernce section of this site.


Regards
Rob McDonald

Don't get hung up on LH-RH talk, your getting good info here. The engine your boat came with was "reverse rotation". Reverse in relation to a standard automotive configuration. If you have found a reverse rotation motor your in the clear. If not you would need a different prop and to index the pump. Its all good, bask in the glory of your new found engine..   

It's STANDARD for the boat or a CC in that they where all reverse rotation engines from the factory until the 90's.

Andrew, if your motor turns a RH prop then is is a reverse rotating engine and not a standard. You have to remember that if you are looking at the engine from the rear, a reverse rotating engine turns clockwise. The same engine when looked at from the front turns counter-clockwise. This confuses many people. The engine you found will be a direct replacement.