Skoda FABIA 2000 Workshop Manual page 61

FABIA 2000 1.4/55; 1.4/74 Engine - Mechanical Components
1) The max. permissible reworking dimension is shown in the figures
for reworking the valve seats as dimension „b".
Reworking valve seats
Reworking inlet valve seat
= ∅ 28.7 mm
a
b = max. permissible reworking dimension
c = 1,5 ... 1.8 mm
Z = Bottom edge of cylinder head
α
= 45° valve seat angle
β
= 30° top correction angle
γ
= 60° bottom correction angle
Reworking exhaust valve seat
= ∅ 25.0 mm
a
b = max. permissible reworking dimension
c = approx. 1.8 mm
Z = Bottom edge of cylinder head
α
= 45° valve seat angle
β
= 30° top correction angle
γ
= 60° bottom correction angle
Procedure
Reworking can be carried out by hand while complying
with the following conditions:
•
Wear limit of valve guides must not exceed the per-
missible dimension ⇒ 15-2 page 4.
•
Use NAC milling cutter with carbide metal tips (min. 90
HRC).
•
Mill with the milling cutter using slight pressure in such
a way that an even removal of swarfs is ensured over
the whole working surface.
Reworking valve seats with NAC milling cutter
–
Place cylinder head on a felt base and secure to pre-
vent it from turning.
–
Match diameter of guide drift to diameter of valve
guide.
Valve guide
Inlet valve
Exhaust valve
–
Match diameter of milling cutter to diameter of valve
seat.
Edition 05.05
S00.5306.06.20
∅ Guide drift in mm
- 0,01
6,0
Repairing Valve Gear
15
S15-0098
15-2 5
page