Show CAUSE OF BAD compression proper amount of clearance necessary to permit valves to seat scat in proper manner an obscure engine difficulty sometimes occurs that is manifested by a reduction of compression when the cylinders are hot although they may be known to be tight when the parts are cold this Is caused by the e expansion an of the vale beems during the warming up process unless a hyop proper er amount of clearance Is till allowed C I 1 between e the ends of the stems and the tappets this may inay be enough to prevent thu the vales from seating properly |