Opinions on valve keepers..... (poll)
http://webbut.unitbv.ro/BU2011/Series I/BULETIN I/Jelenschi_L.pdf
2.1. The importance of valve rotation
The main scope of the valve and tappet
rotation is to reduce the wear, the friction
and to increase the life period of the
components. To maintain the conical valve
face and seat clean of carbon or soot deposit
that might appear on surfaces during valve
opening. To uniform the thermal stress of
the valve head because of the asymmetry
exhaust manifold and uniform the wear of
the conical face, providing a good sealing
of the cylinder [4].
https://www.quora.com/What-is-valve-rotation
engines? If so, then often [if not always] the valves designed to slowly rotate along their longitudinal axis when the engine is working in order for the working surface of their bevels which touch the valve seats to have more even wear: if the valves touch their seats in the same position every time the valve closes there is risk that the working surface can lose it’s roundness quickly.
How much more proof do you want...where is yours?
