alternate rocker thrust washer

[baz]

Hello ,
That's exactly the way to go. You may need to center the rocker to the top of the valve. It may add a bit of mechanical noise because of a bit of backlash to pthe rocker. I do the very same thing when I do my big valve conversions.
The only question is: Does the rocker really need to touch the valve top in the center? If it touches it off center, the valve might rotate, which would be good for the wear of the sealing surfaces. But that 's theory.
Best Regards
Klaus

I always shim the rockers the centre of the valve tops
But Klaus you have given me something else to think about now!!
Is the valve turning a good thing??

 

[marinatlas]

Two ways of center the rocker/valve top , you could (and should) from left to right (or right to left) but front to aft ...........no way , me think Klaus say that !

 

[Deets55]

IIRC
Mr. Comstock says keep it in the center of the valve. Off setting to either side induces very little or no rotation. I also believe he said that rotation is not desirable on a stock Commando head.
Pete

 

[Klaus Monning]

I always shim the rockers the centre of the valve tops
But Klaus you have given me something else to think about now!!
Is the valve turning a good thing??

Yes, it is definately advantageous to have the valves rotating. Unfortunately with the valve / keeper- design the Norton valves are clamped between the valve keepers, so they can' t rotate.

The rotational movement also has its advantage for the wear of the valve tops, where we often suffer from grabbing in of the valve adjusters into the tops of the valves. This could also be prevented by using valve caps and very slightly excentric positioning of the rocker- arm to the valve- stem. In this case only the valve cap rotates.

The air- cooled BMWs by the way have a different valve / keeper design. With their design the valves are free to rotate. I used their valves for my big- valve conversion (42/38mm for more than 78mm bore). Certainly their valves are rather short for our purpose but with the thickest valve caps you can get for the old DUCATI singles (8mm stem-diameter and thickness of at least 3,5mm) you can balance the length- difference.
Best regards
Klaus