Rik

That would be because the drives he has do not counter rotate.

It just a different cam, distributor gear, starter and rear main seal that make the engine spin backwards.

Makes a V bottom much more balanced as well with both the propellers and the engines counter rotating.

Only the new ASD8 drop boxes counter rotate.

Gary Anderson

That explains it.
How about custom ground cams? Do most manufacturers have the ability to produce any of thier camshaft profiles in reverse rotation?
Gary

Gary Anderson

And one other followup.
I've seen both gear driven cam (normal rotation cam) like merc uses on their reverse rotation motors, and chain driven (cam also rotates in reverse) for reverse rotation motors. Which do cam makers grind them for?
Gary

Rik

Getting a cam made has not been an issue over the years.

Remember, in the past the majority of marine engines were counter rotated to accomplish the RH & LH task.

Today for some reason, the some ski boats use a reverse rotation engine???

Your cam manufacturer can answer these questions far better than I as they will know what they make.

I'm sure that not every grind is made in RH and LH but the real answer lies with the cam manufacturer.

KNOT-RIGHT

Whats up Rik?

The crane cam used in these engines is the 139741
versions.The counter engine cam has a LH
stamp after the part #
The distributor gear is cut opposite of the normal rotating engine. which allows it to spin the same way as the normal rotating engine. the firing order is opposite on the counter 12756348

If you think about it the distributor would have to spin the same because it drives the oil pump.

However the rear seal is identical on both engines
in this case. Why would it have to be different?

The starters are different.

On this application the props spin inward.

I actualy had to flip the blower drive snout on one of the ( roots)mooneyhams to allow it to spin the correct way sitting on the counter engine. lukily it was symetrical. (Now the mooneyham sighn reads upside down) Try doing that with a whipple. I tried to get procharger to listen forget it. I was going to persue
maybe making a different bracket to allow the centrifigal to mount backwards. it was just to easy to do the roots.

The New ASD # 8,s drop boxes Would be the way to go.
Then I could actually keep a spare engine around.
Rik post a picture of one.

JPD Motorsports

Man some good reading here. will have to post a pic with my measurements from my hull to center of drives to see what drop boxes needed along with what height to mount at.

marinetrans

Gerry, whats up w/ the blue starters. Paint that chit man!

KNOT-RIGHT

Why you not like my Smurf starters?

I sent them to the armature guy who does all are work at the dealership. I told them there going in my boat.
Thats what I got back

The real catch is one of them wasnt disengageing properly after the rebuilds so he came buy the shop and saw them on the engines He said "guess I should have painted them a different color"
He probrobly thought they were going in a bayliner.

Another thing I should have left alone.

Rik

I'm certainly no engine builder but I've been told that the rear main seal is different on the counter rotating engines??

With the standard "Roots" style blowers you will need to rotate the front housing cover to make the blower spin the correct way while the engine runs backwards.

The other style of blowers cannot be counter rotated as one cannot move the drive pulley to change the rotation of the blower.

The new ASD8 drives cannot be mounted at an angle, rather they mount vertically. A stagger setup will require the engines to be staggered. (Of course there are ways around this)

Reed Jensen

Some seals have little "threads" molded into the rubber... these feed the oil back into the engine and facilitate lubricating the rubber seal lip... I know of several european car engines that don't have a "rear seal" as most people know it.. there is no rubber lip at all... there is a "slinger" which directs the oil away from the area that the crankshaft exits the block. Close to the surface of the crankshaft is a housing that is within .001" of the crankshaft... the crankshaft at this area has an "archemedian screw"... which are square cut threads that "thread" the oil back into the sump... Works great... just don't park on a steep hill.... If you were to convert one of those engines into a reverse rotation... then the threads on the crankshaft would draw the oil outward....