Valve guides
Using a micrometer and bore gauge, take diameter readings on
valve stems and guides to determine the stem clearance in the
guide. Be sure to take a reading at more than one place along
the length of each stem and guide.
If the bore gauge is not available, check the end deflection of the
valve stem in place with a dial gauge rigged. Move the stem end
in the directions (4) (5) and determine whether replacement is
necessary or not, by referring to these limiting values:
Valves
Inspect each valve for wear, burn or distortion at its face and
stem and, as necessary, replace it.
Measure the thickness “a” of valve head. If the limit given to this
thickness is exceeded, the valve must be replaced.
Valve head thickness “a”
ENGINE MECHANICAL (F8B ENGINE)
6A-21
Item
Standard
Limit
Valve stem
In
6.965 – 6.980 mm
(0.274 – 0.275 in.)
–––––
diameter
Ex
6.950 – 6.970 mm
(0.273 – 0.274 in.)
–––––
Valve guide
In
7.000 – 7.015 mm
g
I.D.
Ex
(0.275 – 0.276 in.)
–––––
Stem-to-guide
In
0.020 – 0.050 mm
(0.0008 – 0.0020 in.)
0.07 mm
(0.0028 in.)
g
clearance
Ex
0.030 – 0.065 mm
(0.0012 – 0.0025 in.)
0.09 mm
(0.0035 in.)
Valve stem end
Intake
0.12 mm (0.0047 in.)
deflection
Exhaust
0.16 mm (0.0063 in.)
Standard
Limit
0 8
1 2 mm
Intake
0.6 mm (0.024 in.)
0.8 – 1.2 mm
Exhaust
0.7 mm (0.028 in.)
