1.4 Overhauling The Cylinder Head And Valves - GGP WBE 0701 Workshop Manual

18
19
A
B
21
Service manual
1. ENGINE BLOCK - External operations
17
20
Engine WBE 0701-WBE 0704

1.4 Overhauling the cylinder head and valves

NOTE - These paragraphs describe all the
operations for checking and overhauling the
cylinder head;
it is left to the operator to assess the advisabi-
lity of performing all the operations described
or only part of them, depending on the type
of engine problems encountered.
1 - Dismount the cylinder head
2 - Move the rocker arms (17); press down the spring
seal cap (18) and move it sideways to remove from
the valve stem (19).
IMPORTANT - The inlet and exhaust valves are dif-
ferent from each other and can be identified by
the marking «IN» (inlet) and «EX» (exhaust), on the
valve head.
3 - Use an emery cloth to remove all incrustations
from the valve head and check the thickness of the
rim (A); the valve must be replaced if the margin
(A) is less than 0.5 mm (inlet - IN) or 0.5 mm (exhaust
- EX), or if it shows signs of burning.
4 - Check the diameter of stem (B) in several points
and replace the valve if it is less than the following,
even if only in one point:
5,32 mm (inlet - IN)
5,27 mm (exhaust - EX)
NOTE - The valve seats must be ground by
hand, using a special grinding tool with an
angle of 45°.
5 - Insert the pin (20) in the cylinder head valve
guide and then the grinding tool (21).
NOTE - Grinding must be done taking care
to remove as little material as possible.
6 - Use a caliper gauge to check the depth of the
valve seat (C), which must be 1.8 mm; the cylinder
head must be replaced if a greater value is mea-
sured.
pag. 8
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Release 00 - 02/2008