Skoda Octavia Workshop Manual page 88

15
------------ 15-34 ------------
Cylinder Head, Valve Gear
Procedure
Reworking can be carried out manually or with
a machine. It is important that the following con-
ditions are met:
l Wear limit of valve guides must not be
greater than permissible dimension ⇒ page
15-31.
l Use NAC milling tool with carbide metal
blades (min. 90 HRC).
K Reworking valve seats with NAC hand miller
- Place cylinder head onto a felt base and se-
cure against turning.
- Match diameter of guide mandrel to diam-
eter of valve guide.
Exhaust valve
- Match diameter of milling tool to diameter of
valve seat.
Valve seat
Inlet valve
Exhaust valve
K Sequence of milling
1. Machine valve seat with 90° milling tool
until a proper pattern is achieved (do not
exceed max. permissible reworking di-
mension).
2. Chamfer top correction angle with 120°
milling tool until valve seat diameter „a“
is achieved (⇒ page 15-33).
3. Chamfer bottom correction angle with 60°
milling tool until valve seat width „c“ is
achieved (⇒ page 15-33).
Valve guide Guide mandrel
Inlet valve
Milling tool
90°
28
32
OCTAVIA
mm
6.0 0.01
mm
120° 60°
28 30
32 32
Edition 08.98
S00.5104.52.20