Since Phosphor bronze (Cn-Sn-P alloy) has intensity and high thermal
conductivity, it is used in the making of high performance valve guide for high rotation and high
output engine. Moreover, since its rubbing characteristic is higher than
general material, clearance with valve can be made smaller and
attachment of the circumference of valve and operation accuracy can be
improved. This brings about the greatest effects thus the stress fall of
valve system, valve stick prevention, and valve guide crack prevention.
