Skoda Octavia Workshop Manual page 82

15
------------ 15-24 -------------
Cylinder Head/Valve Gear
Procedure
Reworking can be carried out with a machine or
by hand. It is essential that the following condi-
tions are met:
l Wear limit of valve guides must not be
greater than the permissible dimension
⇒ page 15-21.
l Use NAC milling tool with carbide metal tips
(min. 90 HRC).
K Reworking valve seats with NAC hand mill-
ing tool
- Place cylinder head down on a felt base and
secure to prevent it turning.
- Match diameter of guide drift to diameter of
valve guide.
Valve guide
Exhaust valve
- Match diameter of milling tool to diameter of
valve seat.
Valve seat
Inlet valve
Exhaust valve
K Order of milling operation
1. Machine valve seat with 90° milling tool
until a proper contact pattern is achieved
(do not exceed max. permissible rework-
ing dimension).
2. Chamfer top correction angle with 120°
milling tool until valve seat diameter „a“
or valve seat width ”c” is reached (⇒ page
15-23).
Inlet valve
Milling tool 90° Milling tool 120°
mm
41
34
OCTAVIA
Guide drift mm
7.0 -0.0
mm
41
34
Edition 08.99
S00.5127.50.20