CMB 67 rod orientation?

[Terry Keeley]

One face of the bottom end has 2 slots, the other has 3. Which way does it come from the factory?

I've been having issues with the rod contacting the counterweight on the crank and measured the clearance on both sides, either I've worn more on one side or they come that way.

 

[Bert Dygert]

Terry,

I just opened a 67 Blue head up from the factory. The three oil clearances were facing out when I removed the rotor housing assembly.

Hope this helps.

Bert

 

[Terry Keeley]

Terry,

I just opened a 67 Blue head up from the factory. The three oil clearances were facing out when I removed the rotor housing assembly.

Hope this helps.

Bert

Thanks, that's the way I had it in there. The old mule on the dyno must be gettin' tired.

 

[dave roach]

Terry
Is there a rad on the big end of the rod that goes on the crank pin.

Dave

 

[Buckshot]

New .80 rod orientation.

 

[Terry Keeley]

New .80 rod orientation.
View attachment 290790

Great, thanks for that. It looks like it doesn't really matter?

Are those slugs from the factory?

 

[Buckshot]

Great, thanks for that. It looks like it doesn't really matter?

Are those slugs from the factory?

No. Ken Ballard installed them.

 

[Buckshot]

Terry,
Is this the issue you were having? This is out of my V5.

 

[Wasted wages]

Wow,,,, I hate to say it, but the machine work on that crank looks terrible when you enlarge the picture... sharp edges, a raised rib on the leading edge of the wing. ( where the rod was hitting it)

 

[Terry Keeley]

Terry,
Is this the issue you were having? This is out of my V5.
View attachment 295895

Missed this.

Yup, the 67 only has to wear about 0.005" on the lower rod face to contact the counter weight.

Any idea how much that one has worn? How much running time is on it?

 

[DON MAHER]

Terry, I am guessing that you checked to make sure that the rod is straight and not bent? Had a new one that was!

 

[RaceMechaniX]

Buck, have you checked your bearings? I have seen this with collet setups and worn bearings.

 

[Terry Keeley]

Terry, I am guessing that you checked to make sure that the rod is straight and not bent? Had a new one that was!

No, just visually. It was worn so much on the one side there was a groove in the drum but it had many, many gallons through it.

 

[Mike Cathey]

Maybe add a couple more front case gaskets to give the rod some more room to float. The Picco squarecases were notorious for getting hot and pinching the rod between the crank and drum and usually a broken rod to show for it.

 

[CarlHansen]

Guys the crank end float and prop thrust will also reduce the clearance, not sure how this will happen on Terry’s dyno.

 

[Terry Keeley]

Something I noticed that might be contributing to it is the upper rod bushing can get banged out pretty quick, especially after breaking in a new piston & sleeve.

I've started watching that a lot closer now and re-bush them with 544 when they get a little sloppy.

 

[David Murany]

Something I noticed that might be contributing to it is the upper rod bushing can get banged out pretty quick, especially after breaking in a new piston & sleeve.

I've started watching that a lot closer now and re-bush them with 544 when they get a little sloppy.

Does your dyno put any thrust against the engine? I have had to shim all my CMB cranks back to stop this. Small bearing towards transom.

 

[Terry Keeley]

Does your dyno put any thrust against the engine? I have had to shim all my CMB cranks back to stop this. Small bearing towards transom.

Dyno doesn't put any thrust on the engine, this one spent most of it's life in the SAW boat tho...

 

[DON MAHER]

Are you using a pinch collet or a square drive in your SAW boat?

 

[Terry Keeley]

Are you using a pinch collet or a square drive in your SAW boat?

Pinch, thrust is taken on the front engine bearing.