Subaru IMPREZA 2002 Service Manual page 180

CYLINDER BLOCK
MECHANICAL
2. CYLINDER AND PISTON
1) The cylinder bore size is stamped on the cylinder
block's front upper surface.
CAUTION:
Measurement should be performed at a temper-
ature of 20°C
(68°F).
NOTE:
Standard sized pistons are classified into two
grades,
" A
and "6". These grades should be used
as a guide line in selecting a standard piston.
Standard diameter;
A: 99.505
-
99.515 mm (3.91 75
-
3.91 79 in)
B: 99.495
-
99.515 mm (3.91 71
-
3.91 75 in)
H2M1732C
(A) Main journal size mark
(B) Cylinder block RH-LH combination mark
(C) #1 cylinder bore size mark
(D)
#2
cylinder bore size mark
(E) #3 cylinder bore size mark
(F) #4 cylinder bore size mark
2) How to measure the inner diameter of each cyl-
inder:
Measure the inner diameter of each cylinder in both
the thrust and piston pin directions at the heights
shown in the figure, using a cylinder bore gauge.
CAUTION:
Measurement should be performed at a temper-
ature of 20°C (68°F).
Taper:
Standard
Limit
0.015 mm (0.0006 in)
0.050 mm (0.0020 in)
Out-of-roundness:
Standard
Limit
0.010 mm (0.0004 in)
0.050 mm (0.0020 in)
k 1 0 (0.39)
45 (1.77)
80 (3.15)
115 (4.53)
W
Unit: mm (in)
S2M1821 A
(A) Piston pin direction
(B) Thrust direction
3) When the piston is to be replaced due to general
or cylinder wear, determine a suitable sized piston
by measuring the piston clearance.
M E(S0HC)-82