from everything that i have been reading, normally the port engine is a normal counter-clockwise rotation and the starboard engine is a reverse or clockwise rotation coming from the motor....

I am looking to replace the starboard motor in my 1980 Scarab 377 with TRS borg warner velvet transmission and drives...can anyone verifiy if this correct and I would need a counter-rotation motor before I go put the money down on a used one...

thanks

ALL Mercruiser engines are left hand (counter clockwise)rotation as looking at the flywheel from behind the boat. The rotation of the prop is determined in the outdrive.
Looking at the front of the engine the belts will be turning clockwise. Both of your engine are the same.

Are you sure this correct? I know this for all mercruiser engines produced now...but i was told in the 70's and 80's that they produced LH and RH engines....

I have an '89 with twin 454's and they both spin the same direction.

tmobileguy, I believe you are correct. The TRS drive requires a transmission & I cant see a simple velvet drive trans living too long running in reverse under full power. Smokey Yunick used to reverse rotate some of his stock car engines in the late 50s-early60s cause the car would plant itself harder coming out of the corners. Pretty much all you would have to do is grind a reverse cam & dist gear & spin it the other direction

http://www.wikihow.com/Determine-You...ngine-Rotation

I have inboards oviously... I think they did make RH engines...

If you call a merc dealer & give them ser # Ill bet you will find different part# for cams, dist, circ waterpumps, etc. Ran into that problem with a cruiser that blew a starter at the marina I hung out at. Fortunately someone with another cruiser loaned him a starter to get home, they had to pull 3 starters to get it right cause they didnt think port to port. they just grabbed the easiest one to get to

Mercruisers are stern drives. All the Mercruiser stern drive engines are left hand rotation. The Mercury reverse rotation engines were used for twin engine inboard applications where there is no outdrive to reverse the prop rotation. They used the velvet drive transmissions also. A velvet drive can be spun by either direction engine but you must have the pump on the front of the transmission installed (indexed) for the rotation engine it is on. You don't run it in reverse to go forward if you change it to a different rotation engine. You change the pump indexing. Crank the engines with the starters and you will see they turn the same direction.
Prop rotation is determined in the lower gears of the TRS drive.

Sounds like they had to pull 3 starters because none of them knew what they were doing, or too many cold ones.
Port and starboard doesn't necessarily determine rotation. Some boats run better with the props spinning inwards and some run better with them spinning outwards.

Your correct. They most certainly did make RH engines. Read the Tips section of your wikihow link closely. You have a inboard/outboard or sterndrive. A plane inboard as they mention has a straight propeller shaft coming off the end of the transmission and goes through the bottom of the boat. Propellers are on the end of the shafts under the boat and they use a rudder to steer.