19
COMPILER TECO/ATI ENDORSEDDATE
23.06.2003
REG. CODE
1-5302-602
MODEL N°
50884
DATE OF ISSUE
06-03
REVISION 00
X
9
10
11
c mm
13,025÷13,037
a mm
6,960÷6,970
6,945÷6,955
b mm
7,00÷7,01
e mm
13÷13,01
d mm
0,8÷1,0
CHECKS AND OVERHAUL
Guide
Inlet
Exhaust
assembly
Cylinders heads
Parts shown in figure 9.
1.Head - 2.Tappets - 3.Valves - 4.Seats - 5.Guides - 6.Seals -
7.Lower washers - 8.Springs - 9.Top washers - 10.Valve locking
split cones - 11.Rocker arms - 12.Rocker pins - 13.Gaskets -
14.Push rods - 15.Cover tube - 16.O-ring - 17.Camshaft.
The heads are made off aluminium with valve guides and seats are
made of cast iron.
Do not disassemble the head when the engine is hot to
avoid deformation.
Clean heads of carbon deposits and check the cylinder mating
surfaces; if they are deformed they must be ground to a maximum
of 0.3 mm. Check that there are no cracks or other imperfections in
the heads. If defects are encountered the heads must be renewed.
In this case consult the spare parts catalogue.
Valves - Guides - Seats
Clean the valves with a wire brush and renew them if the valve
heads are deformed, cracked or worn.
Check the dimensional conformity of the valve stems (fig. 11) and
the clearance between valve and guide, bore out the guides to the
dimensions indicated in the table (fig. 10).
Renew both guide and valve if the clearance is greater than 0.1mm.
It is always necessary to grind the valve seats when new guides are
fitted.
Oversize valve guides with external diameter increased by 0.10 are
available.
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