Vortec upgrade to 89 5.7 L reverse rotation motor

[dmohring]

Hi,
I've got a 1989 Mercruiser inboard with a REVERSE rotation 5.7 L 260 hp motor. Its got a one pc main seal and hydraulic flat lifters. It also has a Quad jet carb that I would like to keep. I would like to know the following.
- good source for rebuilt Vortec heads and do I need a hardened exhaust seat or not.
- source for intake manifold and part number.
- source for cam which I would like to get a mild upgrade, like a little more lift but not sure how much more lift would affect the valve spring stiffness needs?
- Is there a re-jet kit I would need for the carb or can it be adjusted as is?

Thanks for the input.

 

[Scott Danforth]

your motor would not have been reverse rotation in 1989 the reverse rotation of the prop is simply one motor in forward, one in reverse.

vortec heads are $750 brand new, $500 for a good used set and about $300 to reman them. buy new heads from any GM performance parts dealer.

Intake will depend if you go cast-iron, aluminum or dual alloy aluminum. pure aluminum intakes are used on heat exchanged cooled motors

if you truly have a reverse rotation motor, you need a custom cam.

if not and you have a standard (left hand rotation motor) the Comp Cams XM264H is a good cam. it is what I ran in my 1988 small block in the Cruisers

 

[Bt Doctur]

just to verify what motor you have, what is the sparkplug firing order?

 

[dmohring]

its definitely RH, 1-2-7-5-6-3-4-8 right off the tag and verified by watching it turn. Its an 89 Century 20 ski boat. Just got it as a project boat.

 

[alldodge]

Yep, that is a RH motor.
For a cam I would suggest calling Bob Madara at Marine Kinetics, he can grind you a cam for how ever much HP you want to make. Can also work with you and your local machine shop on specs.

http://www.marinekineticsonline.com/

 

[Scott Danforth]

definitely call Bob on a custom cam.

I would almost want to change the trans vs dealing with reverse rotation cam and crank (crank usually has grooves at rear main to prevent oil from being pumped out thru main seal)

 

[Bt Doctur]

the swirls in the front and rear seals force oil back into the motor and are specific to std and rev rotation
Put the wrong one in and oil comes out of the motor.

 

[Scott Danforth]

the swirls in the front and rear seals force oil back into the motor and are specific to std and rev rotation
Put the wrong one in and oil comes out of the motor.

exactly. when reverse rotation motors were prevalent many years ago, buddy had his motor rebuilt and the machine shop had a reverse rotation crank in his motor. it pumped nearly all the oil out at startup when he was breaking in the cam.

 

[dmohring]

OK I contacted Bob for a custom cam and he may have a core but it will likely be way to expensive for my budget. So.. I would like to see if I can keep my crank rotation right hand and then replace my timing chain and gears with just the 2 gear setup which turns the cam in the standard rotation. This would allow me access to more readily available standard rotation performance cams. The firing order would just be reversed. Am I missing something here? Would this work?

 

[Bt Doctur]

standard motors have the timing chain, crank sprocket and cam sprocket, reverse rotation motors us a crank gear, cam gear and 2 idler gears , no chain.
What do you have in yours? Changing the motor to a standard left hand will be determined by the transmission type, some are reversed by rotating the front pump and changing the prop

 

[dmohring]

If I go to marine engine.com and type in my engine serial of C391818 it comes up with my engine and the cylinder block and cam section shows i have a timing chain and gears. My question is could I convert cam rotation only, not crank, using the 2 gear to gear setup you show.

 

[thumpar]

I would just change it all over to standard rotation and make up for it in the trans. That would keep all your engine components standard and later on you never have to worry about which parts are which.

 

[Bt Doctur]

The 2 gear setup shown IS used for the reverse rotation
Using your serial number the parts components are listed as LH or RH rotation. If you are correct in having a RH motor you have a gear drive for the cam, and a chain drive if it`s a LH motor.Disregarding your firing order for a moment, what is driving the cam?

 

[Bt Doctur]

this is for standard LH motors

 

[Bt Doctur]

 

[Bt Doctur]

This is used for a standard LH motor

https://tse4.mm.bing.net/th?id=OIP.3...DAAAAA&pid=Api

 

[dmohring]

Oh.. sorry, I looked at those parts descriptions again instead of just the picture which showed the timing chain and gears, and yes it does appear I have the 2 gear setup. That means I can run any standard performance cam correct?

 

[dmohring]

by standard I mean it would fit an LH or RH engine.

 

[Bt Doctur]

If it is 2 gears ONLY it is a RH motor using a special cam and main engine seals.

 

[Bt Doctur]

the cams for both motor turn in the same direction no matter what direction the crankshaft turns.