Subaru Impreza 2003 Service Manual page 280

MECHANICAL
F: ADJUSTMENT
1. CYLINDER HEAD
1) Make sure that no crack or other damage exists.
In addition to visual inspection, inspect important
areas by means of red lead check.
Also make sure that gasket installing surface
shows no trace of gas and water leaks.
2) Place the cylinder head on ST.
ST 498267800 CYLINDER HEAD TABLE
3) Measure the warping of the cylinder head sur-
face that mates with crankcase using a straight
edge and thickness gauge.
If the warping exceeds 0.05 mm (0.0020 in), re-
grind the surface with a surface grinder.
Warping limit:
0.05 mm (0.0020 in)
Grinding limit:
0.1 mm (0.004 in)
Standard height of cylinder head:
97.5 mm (3.839 in)
NOTE:
Uneven torque for the cylinder head bolts can
cause warping. When reassembling, pay special
attention to the torque so as to tighten evenly.
ST
(A) Straight edge
(B) Thickness gauge
CYLINDER HEAD ASSEMBLY
(A)
(B)
ME-00285
ME(H4SO)-68
2. VALVE SEAT
Inspect the intake and exhaust valve seats, and
then correct the contact surfaces with valve seat
cutter if they are defective or when valve guides are
replaced.
Valve seat width: W
Intake (A)
Standard 1.0 mm (0.039 in)
Limit 1.7 mm (0.067 in)
Exhaust (B)
Standard 1.5 mm (0.059 in)
Limit 2.2 mm (0.087 in)
(A) (B)
ME-00397
ME-00287