QUOTE(jcd914 @ Sep 26 2016, 06:16 PM)
They are offset from the centerline of the valve so the the wiping action causes the valve to rotate slightly, this helps keep the contact surfaces of the valve to valve seat clean of carbon and reduces hot spots on the valve and valve seat.
There was a member here that had shimmed or machined the rockers to line up dead center but I don't remember who. How much difference it would make, I don't know and it could be years before any difference was noticed.
Jim
Correct and well explained, but shimming is a bandage machining the rocker the arms is the cure,do not change the rocker arm offset to the top of the valve stem.
I'am running the original CB performance ones in my speedster plastic copy with an 1.8 euro carb motor ,I machined the arms and it works fine with arms from an 1.7.
Appears these kits are now poorly made (samba info) and to go to 911 ones is very expensive.
You can still maybe buy the original adjustment screws but I don't know of a source.