WHEN refacing the valve seats of an automobile engine ... a hack saw in four places and driving in four pieces of clocl:spring. These cutters were filed down nearly to the surface of the reamer.

IN THE usual auttmobile poppet valve the poppet or mushroom valves are lifted from their seats by cams and reseated by springs. In a four·cycle motor, the valves in each cylinder are Oiened and ...