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Change Engine from Reverse to Standard rotation

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How old is it? If it is late

How old is it? If it is late model it is likely you can just change the cam and use your original bolt on parts.
 
The Motor is a 1985 GM 5.7 27

The Motor is a 1985 GM 5.7 270 HP The Engine was suppose to be a standard rotation ( Left hand)
 
"Left hand, meaning it turns c

"Left hand, meaning it turns counterclockwise when you look from its rear or front? If it's clockwise from the front, it's standard rotation."
 
"The motor came out of inboard

"The motor came out of inboard set of motors the guy was suppose to send the standard rotation to me and I belive he has sent the reverse rotation , so when I put the starter on the engine it is turning over correct but will not fire up and I belive the distribitor is rotating the wrong way?"
 
"Look at the crank pulley, not

"Look at the crank pulley, not the distributor. The distributor will turn in the reverse direction of the crank."
 
"John, You may be out of luck

"John, You may be out of luck. Take your SN to your local Merc dealer and check the crankshaft PN of the LH vs. RH motors. In 1988 they used a different crank along with front and rear seals. This information is based on 1988 production motors since that's the oldest info I have redily available. I have to believe the earlier motor will be the same.

And yes, the standard rotation distributor turns clockwise. The RH distributor also rotates clockwise. (When you are cranking it the right way)."
 
The motor crank pulley is turn

The motor crank pulley is turning clockwise so you are saying the Distributor should be rotating Counterclockwise? I put a new standard Marine starter in that would make it crank like a standard rotation engine correct? The guy I purchased from said it was a Standard rotation How can i tell if it is reverse or standard rotation ?
 
"A LH, or standard engine, rot

"A LH, or standard engine, rotates counterwise when viewed from the rear, that would be clockwise when viewed from the front. The distributor also rotates clockwise.

I can't speak specifically about your engine. Reverse rotation motors were built differently at different times. Some had gear driven camshafts which caused the cam to rotate opposite of a standard engine where some used a standard chain and gear set, used camshafts which were ground backwards. I would have to think that it your distributor goes in, you're going the right way, but I've been wrong before.

What makes you feel you have a RH engine?"
 
"I think it is a rH because Th

"I think it is a rH because The Distributor is turning Counterclockwise when the motor is turning the correct way for a Standard rotation motor, I checked the crankshaft P/N and they are the same for L/H or R/H and now I am pulling the timing cover to see if it has gears or a timing chain , I am hoping I can swap out the Cam and change to a timing chain but not sure what else needs to be done?"
 
The pistons all need to come o

The pistons all need to come out and be reversed or it will piston slap like crazy! The pin is deliberately offset to prevent this. Running the motor backwards with turning the pistons around will greatly aggravate the condition.

Jeff
 
"So I have to pull pistons out

"So I have to pull pistons out and reverse ? I do not understand, Are you talking about the way it is pineed to the connecting rod is it the same either way? So Pull and turn pistons 180 degrees and reinsert pin? So that means I need to tear down the ahole motor?
John"
 
John;
You may be better off t


John;
You may be better off to trade or sell your drive and get a new reverse rotation drive and prop from SEI or someone.
It sounds like converting your motor may become a nightmare.
 
"The pistons AND the rods are

"The pistons AND the rods are rotated 180 degrees. They'll run in the right direction then. You might be able to do this from the bottom, withoug yanking the heads. Just carefully rotate them 180s and reinstall the rod bearings and etc.

Jeff"
 
"Thanks Jeff,
I talked with t


"Thanks Jeff,
I talked with the Marine shop that is working on this and they said that the pistons and crank should be Ok That they looked them up and there was no difference in the pistons and crank assembly. Could this be correct? They are saying the cam and Timing gears only need to be changed?
I did find out that the guy sent me the reverse rotation instead of the Standard Rotation. I have already had the motor installed at this point and would hate to pull out again. But if your sure about the pistons then I will have to pull
John"
 
"A 5.7L GM engine doesn't

"A 5.7L GM engine doesn't know or care what
direction it runs. The cam shaft- starter
rotation - timing and firing order are changed.
The distributor will turn clockwise with either
rotation, and run the oil pump.
If you have about 18 inches of clearance, in
front of engine, you can replace cam shaft.
I have even cut a hole in a bulkhead, to
get the 18"."
 
An idea to check for reverse

An idea to check for reverse rotation.
Pull the spark plugs - engine rolls easy -remove valve covers -
put a breaker bar with 5/8" socket on crank shaft bolt -
Turn engine counter rotation direction - ( refer to above posts)
If distributor turns clockwise ? - after #1 cylinder intake valve opens -
#2 intake will open - then 7-5-6-3-4-8-
 
"..."I talked with the Ma

"..."I talked with the Marine shop that is working on this and they said that the pistons and crank should be Ok That they looked them up and there was no difference in the pistons and crank assembly."

They looked, huh? And they didn't see a thing! Let me tell you a story...

I built a Caddy 4.9 aluminum V-8 that went into one of my Fiero kit cars. The pistons had an "F" (for forward) printed on them in ink that had burned off long ago. It took several hours with a micrometer to determine which direction the pistons went, and wasn't eyeballing them!

Sure, the "motor will run in either direction", but it'll piston slap like crazy if you don't turn the pistons around.

It's your choice.

Jeff"
 
"John,
Wow what a mess.
As f


"John,
Wow what a mess.
As for the pistons needing to be reversed in order for the engine to run in the other direction this is not true on this engine.
The pistons must face a certain direction this is true but it makes no difference if the engine is running forward or backward.
The pistons must be installed the same no matter which way the engine is turning.

Why would the engine turning the other direction make any difference on which way the pistons face. The pistons still operate the same only the other direction.

Turning the pistons over makes no sense at all to me.


There is nothing in any manuals that I've looked through that says to change the way the pistons are installed for a reverse rotation engine.


John if you do buy into this reversing the piston deal you can not just take the rods loose and turn them around and re-install them.

First the rods must face a certain direction, second the bearings will not fit the same since they have been run, third the rings will be out of alignment.

In my opinion all you need to do is change the cam,the front and rear main seals.
The seals need to be changed because they are designed to keep the oil in. If the engine is turning the other direction the seals would allow the oil to leak out.
But keep in mind the load on all the bearings will now be reversed because the crank is loaded going the other direction. This could be a problem depending on the condition of the bottom end.

The oil pump would turn the same direction as it needs to(turning backwards now because the cam is turning the wrong way reversing the distributor rotation)

Please do not just take my word on this.
Call a machine shop that builds these engines and ask if they install the pistons upside down / facing the rear of the engine instead of the front for a reverse rotation engine.
I'm sure the question will brighton their day.

It's like the 2 stroke engines with electronic reverse. Push a botton and they slow down and the computer will fire the plugs at an advanced position.
This advanced spark makes the engine spin in the reverse direction. Then the computer controling the ignition fires the plugs at the time needed to keep the engine running backwards.
The engine doesn't know or care which way it is turning. It runs as well backwards as forwards.

Good luck with the project."
 
Just a quick added note. The d

Just a quick added note. The distributor gear may need to be changed as well.
 
First Off Thanks for all the s

First Off Thanks for all the support!!!
If the motor was just rebuilt and there were new seals put in and the motor was only cranked going the standard rotation and never started the seals should be Ok ?? Or is there different seals for Standard rotaion and Reverse? The distributor gear? are you talking about the gear on the distributor? the distributor was from my Original Standard Rot engine so I think Iam Ok there?
 
"Hey, Charli, I wasn't tal

"Hey, Charli, I wasn't talking about "turning the pistons over". I said they need to be turned around. Furthermore, I never said the motor would not run if this essential operation was ommitted. What I said was that it will piston slap like crazy. What I did NOT say is that, if the pistons are not turned around, the skirts will tend to crack.


Jeff"
 
"Let's take the rest of Ch

"Let's take the rest of Charli’s comments one at a time:

..."First the rods must face a certain direction..."

Not so. They'll run fine in either direction.

.."second the bearings will not fit the same since they have been run.."

They could care less! Drag racers pull and reuse bearings on a regular basis, and I've yet to see one of them rotation marked!

"third the rings will be out of alignment."

Huh? You think rings don't revolve about the SAME piston in the SAME cylinder? That's why 2 stroke engines have to pin the rings, to keep them from rotating about the pistons.

Jeff"
 
"You need to talk to a good ma

"You need to talk to a good machine shop.
Or, go to iboats.com forum - Mercrusier inboard or I/O
questions.
Post your problem to Bondo or Don, they are both professional
marine mechanics. Both are sharp and very helpful - and
answer quickly. What ever they say - is correct.
You are getting many confusing answers above.
Bondo and Don will know."
 
"Well, I never contribute to a

"Well, I never contribute to a topic unless I have absolute knowledge and experience regarding the subject so not to give bad or misleading information.

This topic is no exception. That's why I have been quiet until now. I have a fair amount of experience with BB RH motors, but very little with SB. I don't want to cloud the water any further, but here's what I know.

I know that a new BB longblock is converted from LH to RH by Crusader by replacing the chain driven clockwise rotating camshaft with a gear driven counter clockwise rotating camshaft. No turning of pistons, no changing of seals, that's it. Obviously some of the bolt-on components also need to change. This would include the starter motor and distributor drive gear.

I also know that the SB motor has been produced in several versions. The Crusader parts manuals show both gear driven and chain driven camshafts in RH motors, depending on the model year. They also show like and different PN crankshafts and seals for RH motors, again, depending on the year. All information I have found tells you to install the pistons with the identifying mark to the front of the engine, and the rods ... well, here read it for yoursself right out of the factory manual: "Important: The mark on the top of the piston must face the front of the engine block. When assembled, the flanges on the connecting rod and connecting rod cap should face to the front of the engine block on the left bank, and to the rear of the engine block on the right bank.

So both the pistons and rods do go in facing a set direction, regardless of whether it is RH or LH.

If it were my engine, in my boat, I would install the new cam and gear, change the distributor gear and run the thing.

By the time you do everything suggested here to "correct" your engine, you might as well buy a new motor.

That's what I know.


Here's what I don't know.

I don't know if a 4.2L Cadillac engine works the same way.

Rick

P.S. Anybody looking for a new 330 hp Gen V 454 RH cam and gear?"
 
"Correction, realizing that y

"Correction, realizing that your original configuration was CCW, you already have the correct distributor gear. You only need to install the original CCW chain driven camshaft with a new chain and gear set. Happy boating!"
 
i agree with rick but dont for

i agree with rick but dont forget about the main seals they will not just leak they will spray. so it looks like your taking the engine out again.
 
"Sir
It would help me to know


"Sir
It would help me to know what transmission you have. But if you have a right hand prop that pushs you foreward, when you want to go foreward, with a standard engine. Then a left hand prop will push you foreward with a counter rotating engine, when you go in to foreward. SO I guess I'm saying switch props and use the counter engine. Originally you where given a prop to match your standard rotation engine. LH or RH. Now you have a counter rotating engine change out the prop. To correct for the engine rotation."
 
Captain Bill.... Hell of an id

Captain Bill.... Hell of an idea.
I only comment because I am in sort of the same situation. My solution was to leave the engine in the garage and buy a second one. Now I know I have a good backup when needed.... just need a reverse prop.

The outdrive is not affected by this rotation?
 
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