Chery A11. Manual — part 19
CAC Gasoline Engine Maintenance And Servicing Manual
31
5.Valve, valve spring, valve oil seal, spring seat assembly
removal and
installation：
Removal：
Using special tools for valve compression, take out valve
locking pieces, don't compress spring excessively, compress
spring enough to slip locking pieces out of its stroke, or valve
stem may be bent.
If valve locking pieces do not come out during spring
compression, remove compression tools, put an appropriate
pipe on spring seat， so the valve locking piece will not be
impacted. Put a wooden block on valve head (with cylinder
head combustion chamber facing workbench), and then strike
pipe end with hammer.
Reinstall special tools for valve spring compression, locking
pieces may be taken out. After locking piece is taken out,
remove compression tools by unbolting slowly.
——Remove valve spring seat and valve spring，take out
valve oil seal spring seat assembly with screwdriver， and
valve oil seal spring seat must be replaced.
——Overturn cylinder head ，remove intake and exhaust
valves.
——Keep each set of valve, valve locking pieces, valve
spring, spring seat in the same plastic bag and mark numbers
on it, so the parts may be installed in the original place.
——Valve standard sizes and clearance：
Unit：Mm
Intake valve
Exhaust valve
grade
Valve stem
diameter
Valve guide
hole
diameter
Clearance
Valve stem
diameter
Valve guide
hole
diameter
Clearance
standard
8.043+0
-0.018
8.063-8.094
8.017+0
-0.018
8.063-8.094
oversize0.4
8.443+0
-0.018
8.463-8.494
0.02-0.069
8.417+0
-0.018
8.463-8.494
0.046-0.095
Fig.38
Fig. 39
Fig. 40
CAC Gasoline Engine Maintenance And Servicing Manual
32
——Measure valve spring free length and spring force:
——Grinding the valve and the valve seat with the valve
conical angle(Intake valve and exhaust valve):
44°30′— 45°30′
valve seat sealing width:
1.75 — 2.32mm
Installation:
——Before installation, make sure that cylinder head has been
cleaned without any grinding material on cylinder head, valve or
valve guide .
——Lubricate the valve stem and guide with clean engine oil.
——Install the valve. notice that the intake and exhaust valve for 478
and 480 are not interchangeable .refer to the previous valve mark for
valve assembly.
——Press the valve spring assembly with oil seal onto the top of
valve guide. apply engine oil on the intake and exhaust valve guide
edge where the valve seals are installed for preventing valve lock
piece groove from damaging oil seal lip. You may protect the valve
lock groove with tape and remove the tape after installing the valve.
——Install the valve spring and spring seat. Compress the spring seat
to expose the lock piece groove with a special compression tool. Then
put the lock pieces into it and release the compression tool slowly and
remove the tool .
——Put the cylinder head on a wood lump after all lock pieces are
assembled. And tap the small head of the valve stem with a plastic or
copper hammer to fit for the valve mechanism.
Compression (mm)
Spring load (N)
Spring free length
L
1
=37.084
422
L
2
=27.7
892.7
L
3
=27.0
945
L
0
=47.2
Fig.42
Fig.43
Fig.44
Fig.45
Fig.42
CAC Gasoline Engine Maintenance And Servicing Manual
33
6.the sizes for intake valve, intake valve seat, exhaust valve seat and valve guide
―the size of intake valve seat and cylinder head valve seat hole
―
the size of exhaust valve seat and cylinder head valve seat hole
—
——the size of valve guide and valve guide hole
Diameter. of intake
valve seat
Diameter of the
cylinder head
valve seat hole
press fit
clearance
Standard
478
41.877
+0.01
-0.01
41.763
+0.025
0
oversize
0.5
42.377
+0.01
-0.01
42.263
+0.025
0
oversize
1.0
42.877
+0.01
-0.01
42.763
+0.025
0
0.079—0.124
Standard
480
43.877
+0.01
-0.01
44.763
+0.025
0
oversize
0.5
44.377
+0.01
-0.01
44.263
+0.025
0
oversize
1.0
44.877
+0.01
-0.01
44.763
+0.025
0
0.079—0.124
Diameter. of intake
valve seat
Diameter of the
cylinder head
valve seat hole
press fit
clearance
Standard
478
35.377
+0.01
-0.01
35.263
+0.025
0
oversize 0.5
35.877
+0.01
-0.01
35.763
+0.025
0
oversize 1.0
36.377
+0.01
-0.01
36.263
+0.025
0
0.079—0.124
Standard
480
38.377
+0.01
-0.01
38.263
+0.025
0
oversize 0.5
38.877
+0.01
-0.01
38.763
+0.025
0
oversize 1.0
39.377
+0.01
-0.01
39.263
+0.025
0
0.079—0.124
Level
The valve guide
hole
The diameter. of
cylinder head tube
hole
press fit
clearance
Standard
13.555
0
-0.01
13.481-13.519
oversize
14.305
0
-0.01
14.231-14.269
oversize
14.505
0
-0.01
14.481-14.519
0.026-0.07
Fig.46
CAC Gasoline Engine Maintenance And Servicing Manual
34
【9】: Removal and installation of the piston and rod assembly.
Removal:
——Remove the crankshaft to the bottom dead center of the
cylinder. Check and make sure that there is a cylinder mark on the
connecting rod and its cap. or make a mark on each cylinder
before removal.
——Remove the connecting rod bolts and remove the rod cap.
Take the connecting rod bushing out and stick on cylinder marks
and labels on the upper or lower halves.
——Push the connecting rod and piston out of the cylinder with a
hammer wood handle. Take the piston and rod out.
——Remove the piston ring with a special tool or the piece of
feeler gauge. And make labels on each cylinder and upper and
lower halves.
——Press the piston pin out of the piston hole and connecting rod
small end with a press . Then put the piston, piston ring and piston
pin together.
Cleaning and inspection:
——Clean and remove the carbon deposits from the piston, piston
ring and piston pin.
——Clean and remove the carbon deposits from the upper
cylinder bore.
——Measure the diameter of cylinder bore. unit: mm
U
——Grind the cylinder bore with the service gauge and the
figured
twins angle is 50°—60°.
——Measure the diameter of each piston of the carburetor
engine.
Measurement should be taken at the position 10mm to the
bottom
skirt. For 480E piston, measurement should be taken at the
478 cylinder bore
480 cylinder bore
1
77.22—77.23
1
79.94—79.95
2
77.23—77.24
2
79.95—79.96
3
77.24—77.25
3
79.96—79.97
Factory
group
4
77.25—77.26
4
79.97—79.98
A
77.51—77.52
A
80.23—80.24
B
77.52—77.53
B
80.24—80.25
Factory
repair
C
77.53—77.54
C
80.25—80.26
standard
77.245—77.255
standard
79.965—77.975
Increase
0.29
77.525—77.535
oversize
0.29
80.245—80.255
For
mainte
nance
Increase
0.5
77.745—77.755
oversize
0.5
80.466—80.475
Fig.47
Fig.48
Fig.49
Fig.50
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