Standard Procedure - Refacing
WARNING: This page is about a different variant/trim than selected.
NOTE:
Valve seats that are worn or burned can be reworked, provided that the correct angle and seat width are maintained. Otherwise the cylinder head must be replaced.
NOTE:
When refacing valves and valve seats, it is important that the correct size valve guide pilot be used for reseating stones. A true and complete surface must be obtained.
- Measure the concentricity of the valve seat using a dial indicator. Total runout should not exceed 0.051 mm (0.002 inch.) total indicator reading.
- Inspect the valve seat with Prussian blue to determine where the valve contacts the seat. To do this, coat the valve seat with Prussian blue then set the valve in place. Rotate the valve using light pressure. If the blue is transferred to the center of the valve face, contact is satisfactory. If the blue is transferred to the top edge of the valve face, lower the valve seat with a 15 degree stone. If the blue is transferred to the bottom edge of the valve face, raise the valve seat with a 65 degree stone.
- Refer to the table below for the proper valve seat width, valve seat angle, valve face angle and valve spring height.VALVE SEAT, VALVE FACE AND SPRING HEIGHT CHART
DESCRIPTION SPECIFICATION SEAT WIDTH INTAKE 0.94 - 1.04 mm 0.037 - 0.041 in. EXHAUST 1.16 - 1.26 mm 0.046 - 0.050 in. SEAT ANGLE (INT. AND EXT.) 44.5° - 45° FACE ANGLE INTAKE 45.5° - 46° EXHAUST 45° - 45.5° SPRING HEIGHT INTAKE 52.1 mm 2.051 in. EXHAUST 51.2 mm 2.016 in. - The valve seat must maintain an angle of 44.5° - 45.0°.
- The valve face must maintain an angle of 45.5° - 46.0° for the Intake and 45° - 45.5° for the exhaust.