Answers my question, chain drive cam.
FYI on most counter rotated marine engines, the cam is gear driven so it spins opposite the crank. These use standard distributors.

As for the rear seals, some old marine engines even had grooves cut in the rear main journal of crank to push oil back in. You spin these the wrong way or use the wrong seal and you'll have a mess in your bilge.
But I did think all Mark IV BBC motors used a "yellow" rear main seal that was designed for counter rotation. Might want to check on this.
Gary

It has been a long winter in building these engines.
I have had different opions and ideas on just about everything I have asked about. From Valve train geomitry to piston wall clearance. They fire right up on the stands and set off every alarm in the cars here at the dealership. Will they stay together? Time will tell. I am currently awaiting dyno time.

In reading this post I remember I was in error in my thinking of counter. this post clarified it for me.


http://www.offshoreonly.com/forums/s...unter+rotation

The seal pictured below is the felpro 2904
this seal was on the counter and the normal rotating.
These engines had 150 hours on them before I pulled them apart with no leaks. The cranks are sonny bryant
with no machining on the rear main journal. Perhaps thats why it dosnt leak.

Now is certainly the time to find any problems.

The 72C transmissions with 6 cluches worked well for me with the 600 hp motors.However the 900 hp,s
required me to upgrade to 10 fiber cluches.

Gerry

Might be worth checking on that seal. See this post as a possible result of using the wrong seal.
http://www.offshoreonly.com/forums/s...tion+rear+seal

Do we have any pics of the asd's with the mounts inside the engine compartment transom to go with the one that is shown externally please.

I see what you mean Gary.


:confused: confuses me that it worked for over 150 hrs
(4 years hard offshore running )

The mains look as new.

Reverse Rotation
 

I am glad to see someone else is building a wrong hand turn engine.

Three things I would like to add from my experience.

1. If you use a reverse rotation camshaft with a new distributor gear, check the distributor! Most distributors are only made to handle the upward thrust of the helical gear set. This pushes the distributor shaft up into the housing and is addressed with the thrust washer behind the gear. When you change the direction of the thrust with the RR cam/and the reversed helical distributor drive gear the distributor shaft is now being pulled down into the engine. Some marine distributors have bearings to support both loads. If you don't check, it will fail the distributor and increase the wear on your oil pump.

2. Check the pistons for offset. Position two identical pistons with the "front of engine" mark in opposite directions. Slide one wrist pin into half of each piston and check for offset. If you have offset turn the pistons around on the rods, if not leave her be....

3. Use a bi-directional waterpump.


I am working to reverse rotate a 181 cubic engine four cylinder. They were never offered as a reverse rotation marine engine. However after a detailed review of the parts book the 91 and 92 pass car engines had timing chains instead of timing gears. So with any luck I can take the gears off, "slap" on the chain/ sprocket assembly, change two wires at the cap and be on my way. Well it is not quite that simple, but much cheaper than a reversing gear.....