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convert Chev vortec 330 hp to reverse rotation?

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tronic72

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Hi,

I have a 31 foot cabin cruiser with 2 x 230 HP inboard Mercruisers. These have reached the end of their lives. I'm considering purchasing two GM vortec engines to replace them and then bolting on the accessories and transmissions. As it's a duel engine boat, one of the engines turns counter clockwise and one clockwise (forget which is which). This means that one of the GM engines will need to be converted to reverse rotation. Has anyone has any experience with this process? I know there's different methods of doing this and some require a new cam and others do not. I'm not quite sure on which method would be best or even possible for the GM engines. Any help would be great.

Thanks, Mark
 
My suggestion would be to trade in your transmission for a reverse rotation transmission instead of a reverse rotation motor....

Then you would have identical motors and complete parts swapping ability if needed.........

other than that suggestion I do not have any direct experience with converting a standard rotation to a counter rotation.
 
Listen to Jack! That is the ONLY way to go. Trust me, for assbackwards engine parts are getting harder and harder to find since it's old technology.

Jeff

PS: The starboard engine is usually the reverse rotator (unless it's a Vee drive or an old Chris Craft conversion, which nobody can figure out!)
 
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tronic72 said:
..................
I'm considering purchasing two GM vortec engines to replace them and then bolting on the accessories and transmissions. As it's a duel engine boat, one of the engines turns counter clockwise and one clockwise (forget which is which).
If straight shaft drive (not V-drives), your Port Engine will be Standard LH Rotaion (counter-clockwise when viewed from the flywheel end)
faq-ro5.jpg


Your Starboard Engine will be REV RH Rotation.
(just opposite of the above)


This means that one of the GM engines will need to be converted to reverse rotation. Has anyone has any experience with this process? I know there's different methods of doing this and some require a new cam and others do not. I'm not quite sure on which method would be best or even possible for the GM engines. Any help would be great.
First off.... a true 330 hp 5.7L SBC Vortec Engine will not be built correctly for Marine Engine use. (this sounds more like a HP automotive Engine)

The typical Marine 5.7L Vortec Engine's hp is not truly near 330 (look at the specs and at the RPM at which rated).

In either case, in order to reverse the rotation, the piston wrist pin off-set must be reversed.
(the dreaded GM full-dished pistons can be reversed)

Front and rear crankshaft seals must be correct for RH roation (if not, they will weep and leak).

The camshaft (whether chain/sprocket driven or gear driven) will be completely different from that of a Std LH rotation engine.

Oil pump and Ignition distributor can remain the same after the firing order has been changed.


Thanks, Mark
Click to expand...

My suggestion would be to trade in your transmission for a reverse rotation transmission instead of a reverse rotation engine....
If this is to be done, you would want an "oposite of engine rotation" transmission...... (not a reverse rotation transmission!)
A transmission that is reversable, will simply allow the prop shaft to follow the Engine rotation, and I doubt that you'd want two (2) LH propellers on this boat!

An "oposite of engine rotation" transmission (on Stdb side) will allow for a Standard LH Rotation (counter-clockwise) engine, yet it will spin a RH propeller for the Starboard side.


I'm not suggesting that this is the correct answer, because you would have other things to consider as well.
Over-all gear reduction (i.e., ratio), transmission length, and so on.


other than that suggestion I do not have any direct experience with converting a standard rotation to a counter rotation.
(See above)
Click to expand...






.
 
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kghost said:
My suggestion would be to trade in your transmission for a reverse rotation transmission instead of a reverse rotation motor....

Then you would have identical motors and complete parts swapping ability if needed.........

other than that suggestion I do not have any direct experience with converting a standard rotation to a counter rotation.
Click to expand...

Thanks to everyone for their suggestions. The transmission reversing the direction was not even a scenario I thought about. I've done a heap research on reversing the engine and this sounds much easier.

My next question (fingers crossed here) is...is my existing transmission a reversing type?

The model number is 10-17-006.

Thanks so much for all your replies.
 
Probably. Note that the pistons also have to go in backwards ("F" to the rear) when running assbackwars.

Jeff
 
kghost said:
I'm not suggesting that this is the correct answer,


Yup!
Click to expand...

Jack, I think that you've taken my comment somewhat out of contex.
Here's what I said, and why:

"I'm not suggesting that this is the correct answer, because you would have other things to consider as well.
Over-all gear reduction (i.e., ratio), transmission length, and so on. "

In other words........ if Mark was to change transmission design and type only as to accommodate a Std Rotation Engine on the Starboard side.

Correct for me would be to build or purchase either:
a ...... a RH REV Rotation Engine.
b ...... an "Opposite of Engine Rotation" transmission (of the same foot print and workable reduction).

Either scenario would give Mark a RH propeller on the Starboard side.






.
 
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kghost said:
http://www.velvetdrive.com/marine.html


"""""Fully reversing feature allows for Twin Engine installation using Automotive Rotation Engines (Standard marine rotation) and Compact design ...""""
Click to expand...
Yes, and Mark would also end up with two (2) LH propellers.
If that is not a concern for Mark, then there ya go! :D



tronic72 said:
Thanks to everyone for their suggestions. The transmission reversing the direction was not even a scenario I thought about. I've done a heap research on reversing the engine and this sounds much easier.
Mark, as suggested above.........., by using two Std LH Rotation Engines, and by reversing the one Starboard transmission, you will end up running two (2) LH prpellers.
(a Reserve Capable transmission only means that it can/will follow Engine rotation and that the oil pump will still function for the selected direction)

The only way to reverse the shaft direction from that of a Starboard LH Rotation engine, would be to install an "Opposite of Engine Rotation" transmission.
Click to expand...



fastjeff said:
Probably. Note that the pistons also have to go in backwards ("F" to the rear) when running assbackwars.

Jeff
Click to expand...

Jeff, all due respect....., if Mark is looking at two 330 horse power 5.7L SBC Vortec Engines, they are likely HP Automotive (not suited for Marine cruiser use).
And if the build produces an honest 330 horse power, then GM most likely did not use their dreaded Full Dished pistons (shown below).


images

images



The GM full dished pistons (shown above) are ambidextrous, and can be fit into any bore (one large dished area.... same sized double valve reliefs).
They can also be flipped 180* (on the connecting rods) as to change the wrist pin off-set.
By doing so, nothing but the wrist pin off-set has changed.


With a more High Performance style piston (with a quench surface and specific sized single valve reliefs), this cannot be done quite as easily.

images






****************************************************

Mark, I am curious as to how 330 horse power can be derived from a 5.7L SBC Vortec Engine at an RPM suitable for Marine Cruiser use.

Can you tell us more about these ?
Are these being sold for Marine Cruiser use?
Are these coming from GM, or are these coming from another source?










.



 
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Bt Doctur said:
there the 6.2L motors. 5.7 block and bore, stroker crankshaft
Click to expand...

Bt Doc......... that was my error in thinking that these were 5.7's . .... duh! :eek:

The GM 6.2L is a 377 cu in SBC (std 4.000" bore), and still uses the dreaded GM Full Dished pistons.



Mark, here's your scenario should you install two Std LH Rotation Engines, yet wish to run a RH propeller on the Starboard side.
 

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RicardoMarine said:
Yes, and Mark would also end up with two (2) LH propellers.
If that is not a concern for Mark, then there ya go! :D



OMG.............if you get a reverse rotation transmission then that would be the same as having twin I/O's with one with a counter rotation lower or twin outboard with one with a counter rotation lower.

Same thing............Have another dished Danish piston with your coffee please!!!!!!!!

Reverse rotation transmission = counter rotation................ugggggggggggggggg

For his information...

A standard marine engine when looking at it from the back of the boat, the engine rotates counter clock wise, this is how they describe it in the industry.
This is also considered STANDARD rotation.

just for his reference.........
Click to expand...
 
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RicardoMarine said:
Yes, and Mark would also end up with two (2) LH propellers.
If that is not a concern for Mark, then there ya go! :D


Gents,

http://inboardmarines.com/products/5.7L%7B47%7D350,-330HP-Vortec-Marine-Base-Engine.-Replaces-Mercruiser-years-96%252dup.html






Jeff, all due respect....., if Mark is looking at two 330 horse power 5.7L SBC Vortec Engines, they are likely HP Automotive (not suited for Marine cruiser use).
And if the build produces an honest 330 horse power, then GM most likely did not use their dreaded Full Dished pistons (shown below).


images

images



The GM full dished pistons (shown above) are ambidextrous, and can be fit into any bore (one large dished area.... same sized double valve reliefs).
They can also be flipped 180* (on the connecting rods) as to change the wrist pin off-set.
By doing so, nothing but the wrist pin off-set has changed.


With a more High Performance style piston (with a quench surface and specific sized single valve reliefs), this cannot be done quite as easily.

images






****************************************************

Mark, I am curious as to how 330 horse power can be derived from a 5.7L SBC Vortec Engine at an RPM suitable for Marine Cruiser use.

Can you tell us more about these ?
Are these being sold for Marine Cruiser use?
Are these coming from GM, or are these coming from another






.
Click to expand...
http://inboardmarines.com/products/...ngine.-Replaces-Mercruiser-years-96%2dup.html
 
tronic72 said:
Thanks to everyone for their suggestions. ....The

My next question (fingers crossed here) is...is my existing transmission a reversing type?

The model number is 10-17-006.

Thanks so much for all your replies.
Click to expand...

The mode number for your gear shows it to be a 71 series velvet drive, configured for a RH engine. It is NOT a "full power reversing" type of gear. If you want to use a LH engine, you'll need a 5000 series velvet drive, or something similar...

Though the title says 330 hp, the original post had 230hp.....standard 305 SBC rating for the time.....just my two cents
 
Hi Everyone,

based he'd on what I've learned since the initial reply to my OP I think that 2 left hand (standard) turning engines is a much easier proposition. Now the only thing I need to figure out is:

1. Is my existing transmission one of the reversing (CR) types
2. If not, can I convert mine to a reverse type... And if not.....
3. Where can I get one.

As I previously stated mine is the 10-17-006. Apparently this replaced or is the same as the AS2-71CR. Where the CR denote the reverse type.

If there's a velvet drive expert that could tell me that would be great.

Im surprised none of you have heard or the 330 HP vortecs for marine use. They seem to be very common. Even here in Australia. In my previous reply I found a link in the US in 10 seconds. Hopefully they are okay??? The units I'm looking at are brand new. Four bolt mains and roller cams . They seem like very well built engines.

Am I missing something?
BRAND NEW 350 CHEVROLET VORTEC ROLLER CAM LONG ENGINES .
THESE ENGINES HAVE 4 BOLT MAINS , BRASS WELSH PLUGS & HORSEPOWER IS 330HP.
THESE ENGINES ALSO HAVE MARINE HEAD GASKETS FITTED TO THEM SO CAN BE USED FOR BOTH CAR / MARINE APPLICATIONS.
COMES WITH A 12 MONTH - 20,000KM WARRANTY.
Specifications:
Horsepower:330 hp @ 5,000 rpm
Torque:380 ft/lbs @ 3500 rpm
Compression Ratio:9.1 to 1
Block:Cast Iron 4-bolt, 4.000" Bore
Crankshaft:Cast Nodular, 3.480" Stroke
Heads, Chamber Size:Vortec Cast Iron, 64cc Chamber
Valves (I/E):1.940"/1.500"
Camshaft, Lift (I/E):0.431"/0.451" Hydraulic roller cam
Camshaft Duration @ 0.050" I/E:196/207 degrees
Intake Manifold:Not Included

 
Yes the original post was about converting the 330 vortecs to right-hand. The current engines are 230 HP mercruisers. From which I hope to transplant the bits.

Based on the previous posts I think reversing the velvet drive seems a much simpler option.
 
The CR is "old" velvet drive jargon for counter rotation - it does NOT mean full power reverse. A velvet drive has it's output rotation the same as the input rotation, except for the 1.88:1 gearing. There's NOT a 71 series drive that will do what you want.
 
Mark, let me apologize for Jack's attitude….... he often disagrees with me and does not know how to do so in an adult like manner. :eek:





Just to be clear.... are your newly proposed engines 5.7L SBC Vortec engines............ or are these 6.2L SBC Vortec engines?????


I will suggest this once again…....
If you wish to maintain a right-hand rotation propeller on the starboard side, you will need to do one of two things:

a...... Purchase or build a reverse right-hand rotation engine for the starboard side and continue using your OEM Stbd side transmission.
b...... Install two Standard LH Rotation Engines, and use a transmission that is "opposite of engine rotation" capable or "Fully Reversing" on the starboard side .

Transmissions that allow for "Opposite of Engine Rotation" or "Fully Reversing" are:

Volvo Penta AQ series stern drives..... either prop rotation can be achieved.
Volvo Penta MS-3 and MS-4 style I/B transmissions...... either prop rotation can be achieved.
Inboard transmissions that are "Opposite of Engine Rotation" capable or "Fully Reversing" ......
and again, either prop rotation can be achieved.
See more here.




As I think MakoMarks suggests below, many I/B transmissions are capable of operating behind either LH or RH rotation engines.
The FWD gear is still selected for forward propulsion when installed behind either LH or RH rotation engines. The output shaft (while in FWD gear) will follow the engine rotation..... ( I.E., RH engine will spin a RH prop..... LH engine will spin a LH prop. )
The transmissions's oil pump is re-indexed as to operate correctly as per engine rotation as to continue lubricating correctly.
IOW...... a "non-opposite of engine rotation" transmission (that may be reverse rotation capable), simply follows Engine rotation while engaged in the "forward" gear selection.
These may not be capable of offering opposite of engine rotation while under forward propulsion.
In other words, you may not be able to simply operate one of these transmissions in Reverse Gear while propelling the hull forward under full and more constant loads.

Examples:

If you were to use a LH Engine on the Port side, and wished to turn a LH propeller (as most do), you would need to operate the transmission in Forward Gear!


If you were to use a LH Engine on the Stdb side, and wished to turn a RH propeller (as most do), you would need to operate the transmission in REVERSE Gear!

Unless the transmission is "Opposite of Engine Rotation" capable, or "Fully Reversing"......, you would cause damage to it.




makomark said:
The mode number for your gear shows it to be a 71 series velvet drive, configured for a RH engine. It is NOT a "full power reversing" type of gear.
If you want to use a LH engine, you'll need a 5000 series velvet drive, or something similar...
Click to expand...

Thank you, MakoMark.
This is what I've been attempting to explain to the other Mark (the OP here).


tronic72 said:
Hi Everyone,

based on what I've learned since the initial reply to my OP I think that 2 left hand (standard) turning engines is a much easier proposition. Now the only thing I need to figure out is:

1. Is my existing transmission one of the reversing (CR) types
See MaKoMark's responses above and below.
Mark is confirming what I've been trying to tell you, and Mark can actually quote model numbers to you.

2. If not, can I convert mine to a reverse type... And if not.....
Let's all be on the page regarding the language.
We have transmissions that are cable of either hand engine rotation.... and we have transmissions that are "opposite of engine rotation" or "fully reversing" capable.
The two applications do not necessarily interchange.


Im surprised none of you have heard or the 330 HP vortecs for marine use. They seem to be very common. Even here in Australia. In my previous reply I found a link in the US in 10 seconds. Hopefully they are okay??? The units I'm looking at are brand new. Four bolt mains and roller cams . They seem like very well built engines.
Am I missing something?
Yes.... I think so if you are counting on pulling 330 hp from one of these under common cruiser engine RPM.
You'll also have 9:1 static C/R w/ GM full dished pistons! (Not very desireable for Marine use)

Look at the RPM at which the hp rating has been taken.
Taken directly from the spec sheet:
"Peak torque is 355 lb-ft @ 3600 RPM while peak horsepower is 330 hp @ 5,000 RPM"
These are erroneous numbers being used for sales purposes.
No one operates a Marine Cruiser Engine at 5k RPM. :rolleyes:


If you are wanting or needing more power, go with the new GM 6.2L engines. The 6.2L engine is a SBC 5.7L w/ std 4.000" bore and with the 3.750" stroke.
Better yet, build a pair of Q/E 6.3L SBCs yourself... and make one of them RH Rotation. ;)
The 6.3L engine is a SBC 5.7L w/ .030" over-bore (4.030") and with the 3.750" stroke, and you can select your own Q/E style piston profile.
Click to expand...

makomark said:
The CR is "old" velvet drive jargon for counter rotation - it does NOT mean full power reverse. A velvet drive has it's output rotation the same as the input rotation, except for the 1.88:1 gearing.
There's NOT a 71 series drive that will do what you want.
Click to expand...
Yes and Yes!




.
 
Last edited:
RicardoMarine said:
Mark, let me apologize for Jack's attitude….... he often disagrees with me and does not know how to do so in an adult like manner. :eek:





Just to be clear.... are your newly proposed engines 5.7L SBC Vortec engines............ or are these 6.2L SBC Vortec engines?????


I will suggest this once again…....
If you wish to maintain a right-hand rotation propeller on the starboard side, you will need to do one of two things:

a...... Purchase or build a reverse right-hand rotation engine for the starboard side and continue using your OEM Stbd side transmission.
b...... Install two Standard LH Rotation Engines, and use a transmission that is "opposite of engine rotation" capable or "Fully Reversing" on the starboard side .

Transmissions that allow for "Opposite of Engine Rotation" or "Fully Reversing" are:

Volvo Penta AQ series stern drives..... either prop rotation can be achieved.
Volvo Penta MS-3 and MS-4 style I/B transmissions...... either prop rotation can be achieved.
Inboard transmissions that are "Opposite of Engine Rotation" capable or "Fully Reversing" ......
and again, either prop rotation can be achieved.
See more here.




As I think MakoMarks suggests below, many I/B transmissions are capable of operating behind either LH or RH rotation engines.
The FWD gear is still selected for forward propulsion when installed behind either LH or RH rotation engines. The output shaft (while in FWD gear) will follow the engine rotation..... ( I.E., RH engine will spin a RH prop..... LH engine will spin a LH prop. )
The transmissions's oil pump is re-indexed as to operate correctly as per engine rotation as to continue lubricating correctly.
IOW...... a "non-opposite of engine rotation" transmission (that may be reverse rotation capable), simply follows Engine rotation while engaged in the "forward" gear selection.
These may not be capable of offering opposite of engine rotation while under forward propulsion.
In other words, you may not be able to simply operate one of these transmissions in Reverse Gear while propelling the hull forward under full and more constant loads.

Examples:

If you were to use a LH Engine on the Port side, and wished to turn a LH propeller (as most do), you would need to operate the transmission in Forward Gear!


If you were to use a LH Engine on the Stdb side, and wished to turn a RH propeller (as most do), you would need to operate the transmission in REVERSE Gear!

Unless the transmission is "Opposite of Engine Rotation" capable, or "Fully Reversing"......, you would cause damage to it.






Thank you, MakoMark.
This is what I've been attempting to explain to the other Mark (the OP here).





Yes and Yes!




.
Click to expand...


HERE IS THE BOTTOM LINE.

If there is one thing that is true in the above quote and that is if you research this forum you will see it at least 500 times.
That is my issue..............WHO THE F^CK cares about that! Not me and not millions of others.........

Other than that I would STRONGLY advise to completely disregard it! There are hundreds of thousands of that motor design in use all over the world.............

If you or anyone else wants to purchase a new or rebuilt marine motor then do so with 1000% confidence that the motor builder or manufacturer knows a lot more then the "piston design or choice" then expert RICK.

Do not be baffled by his bull SH!t............. I say this only as a precaution!

I as many others who contribute here have a life time of experience so do what most do......take the outliers comments with a grain of salt.

If you are in Australia then go to a seaside marine business and discuss with them about a reverse rotation transmission so you can run a standard rotation motor. See what they have to say.

Other wise purchase a reverse rotation motor and DO NOT CONVERT a standard to reverse!! And be done with it.

I posted a link to the BorgWarner/velvet drive web site.

Call the and ask your questions directly if it is not to expensive to call , I would assume they have an office in Australia see if they do and call them.
 
Last edited:
Mark, if you have any doubts, I would encourage you to further research any of this information for yourself.

I'm having coffee and reading your email. I will respond shortly.


Jack, feel free to disagree with me, but when/if you voice your opinion, please do in an adult like manner.
And for God's sake..... quit reading my posts if they are so upsetting to you.



.
 
I would strongly suggest stop posting the exact same responses each and every time someone posts about replacing an engine. YOU ARE NOT AN EXPERT!

I don't really give a sh!t what you or anyone else thinks about my opinion..........

Your chronic repeat posts are getting very old and f^cking annoying!

Let them figure it out or simply message them with all that piston crap and engine "expertise?" you constantly post.

Information overload....................KISS

Keep it simple STUPID!!

For Christ sake............
Do you actually think that every one of the thousands of engine remanufactures or builders don't know what there doing and YOU do?

Its the same old song and dance from you...........every time...........

Why not create your own web page and simply link to it when responding............That way you don't clog up the forum post with the same overloaded posts over and over and over again.
 
disgruntled non-polite member with an ill tempered attitude said:
For Christ sake............
Do you actually think that every one of the thousands of engine remanufactures or builders don't know what there doing and YOU do?
Click to expand...

Certainly not.
Many of these builders know exactly what they are doing, and exactly how to sell an easy-to-build and cost-effective Engine.
Using the GM full dished piston is greatly acceptable. In fact, most boat owners aren't even aware of a better and more suitable SBC Engine build using other than the GM pistons.

However.... if you were to ask this same Engine builder if they understood the Quench Effect and why it is important for a true Marine SBC Engine, most are going to be on-board with the idea.

However #2...., this build costs more, and it involves careful consideration of (1) piston selection, (2) calculations of piston deck height (3) compressed head gasket thickness, all in order to achieve the proper quench dimension.
It's all about achieving the correct LPCP.... of which is not arguable!!!!!

If a machine shop is unwilling or incapable of doing this, then I'd certainly avoid using them.



.
 
I'm still interested in what steps are done to make this change. Regardless of the engine. Has anyone done this successfully?
 
In my opinion if you purchase two new (either new or remanufactured),

Make sure intake manifolds are the correct ones for the motors. Newer motors use a different bolt pattern than the older. 8 bolts vs I think 12.

Make sure they have the correct harmonic balancers,

The correct starters (mainly for the reverse rotation)

The newer motors may require a different starter based on the way it is mounted (straight mount or offset)....not sure but an inquiry to the motor supplier may answer this.

Also you will need to consider the flywheels and if they will need to be rebalanced before installation and of course if they will bolt up to the newer crankshaft. If not you will need new flywheels to match the newer flywheel configuration.

Don't forget the fuel pump whether mechanical vs electric.


Carb recalibration as per email.

Other than that I would expect everything else to be plug and play
 
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