View Full Version : Changing LH rotation inboard motor to RH rotation

08-16-2000, 12:09 PM
If anyone out there has any knowledge of what parts have to be changed in a Mercruiser left hand rotation motor to change the motor back to a right hand rotation motor your insight would be greatly appreciated.

sonny benfield
08-19-2000, 08:04 PM
" I think that just the cam shaft will do the trick for rotation,but you have to mount the starter either in front of or behind the flywheel to get it spinning in the desired direction. i have these parts listed in a chris craft manual ....i,ll check to make sure i,m telling you right. "

09-05-2000, 11:50 PM
don't forget you have to change the prop to right hand. and you have to change the starter to right hand drive . if you have a velet drive trans. you can change the rotation of the prop without changing the engine. get a trans. manual and find out which way you turn the gear housing a 1/4 turn and the output will now be right hand. this will save a lot of time with the engine

09-19-2000, 10:19 PM
Parts required:
-reverse rot. camshaft
-timing gear set
-reverse front seal
-reverse rear seal
Pump cover on transmission must be rotated 180 degrees (note arrow on front cover must coincide with rotation of engine)
Finally change propeller to an opposite rotation prop.

Michael Forbis
10-05-2000, 10:33 PM
" Gee - this is not a good idea!

1. Change camshaft to standard rotation, then, standard practice is to replace lifters with camshaft

2. Replace timing gears with chain set (same as automotive)

3. New front seal (same as automotive)

4. Pull the pan and remove the rear main seal (replace with automotive)

5. Pull out the all the pistons and rods. take them to a machine shop and have all the pistons reversed. Notice the notch on the pistons when you pull the heads off on a counter rotating motor - they point to the rear of the engine! Yes, this is true. And the machinist will tell you your crazy to reuse the pistons. So, like the camshaft - bore and hone the block and buy new pistons.

6. Then, if you plan to reuse the starter... open it up and rotate the field housing 180 degrees and replace the bendix - lead in cut on opposite side of the gear teeth.

7. If you have a velvet drive transmission follow what Dave said in his post. But, your nuts to spin a old pump backwards.

See why this is a such a bad idea? Also, the stress cracks (microscopic) in the crank will not be loaded in the other direction.

Suggest you sell the motor as a LH and buy a RH or plan on a complete rebuild "

10-28-2000, 08:54 PM
LISTEN TO MICHAEL!! I have gone down that very
costley road.It's no fun and very expensive.

01-24-2002, 02:06 PM
Why change engine rotation you can do it in the trans.If you have velvet drives just turn the pump around