Subaru IMPREZA 2004 Service Manual page 161

Color of spring part:
Intake [Silver]
Exhaust [Silver]
ST2
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
ST1
ME-00284
(A)
(B)
ME-00285
ME(H4SO)-65
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)
3. VALVE GUIDE
1) Check the clearance between valve guide and
stem. The clearance can be checked by measuring
the outside diameter of valve stem and the inside
diameter of valve guide with outside and inside mi-
crometers respectively.
Clearance between the valve guide and valve
stem:
Standard
Intake 0.035 — 0.062 mm (0.0014 — 0.0024
in)
Exhaust 0.040 — 0.067 mm (0.0016 —
0.0026 in)
MECHANICAL
(B)
ME-00397
ME-00287