ARMY TM 9-6115-670-14&P 6-22 ADJUST a. Use a valve grinder to grind the face of the valve to a 45 to 45.5 angle. b.  Correct valve seat. Proceed as follows: (1)     Use a 45 valve seat cutter to grind the valve seat surface (1, Figure 6-7). (2)     Apply red lead to valve. (3)     Fit valve in valve seat and visually check the contact position of valve face and valve      seat (2). (4)     Grind the upper surface of valve seat with a 15 valve seat cutter until the contact area between valve seat and valve face is centered on the valve face. (5)     Use a 45 valve seat cutter and regrind valve seat. (6)     Check the contact between the valve and valve seat. (7)     If contact between the valve and valve seat is not correct, repeat steps b(3) - b(6) until the correct contact is achieved. (8)     Once correct contact is achieved, lap the valve (para 6.7., ADJUST) until the seated rate becomes more than 70% of the total contact area. NOTE Before adjusting the valve and seat, check clearance between valve stem and the valve guide (para 6.7., steps c. and d.). NOTE After adjusting valve seat, check cylinder head for valve recessing (para 6.5., TEST, step d). WARNING Wear   protective   gloves   when   using   red   lead   and dispose of red lead in accordance with local ordinance. NOTE If the valve has been used for a long period, the seat will tend to come in contact with the upper side of the valve face.