Hi all !
I bought 4 new competition exhaust valves with a diameter of 30.9mm for the BMC
A 1275cc engine.
I recognized that these valves wobble around in the cylinder head valve seats
when being turned.
The reason is that the valves are slightly asymmetric, i.e. the area which is
designed to have
contact with the cylinder head valve seat is not symmetric. This area is
smaller on one side and
bigger on the other side of the valve. And this is the same for all 4 valves!
(Can easily be seen by turning the valves with an electric drill.)
Is this a manufacturing error or is this a feature, e.g. to cause rotation of
the valves when
they are closing ??
(Lapping the valves does not help in this case because you can not lap the
cylinder head valve
seat to an asymmetric valve !)
Any ideas about this phenomenon ?