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Workshop manual
Stem – to - guide clearance
Subtract each valve stem OD from the corresponding guide ID to
obtain the guide-to-stem clearance.
Standard
IN
0,02 - 0,044 mm
EX
0,06 - 0,087 mm
If the stem-to-guide clearance exceeds the service limit, determine if
the new guide with standard dimensions would bring the clearance
within tolerance. If so, replace the guide (or cylinder head) as
necessary and ream to fit. If the stem-to-guide clearance exceeds the
service limit with new guides, replace the valves as well. Recondition
the valve seat whenever the valve guide is replaced.
Cylinder head service
Exhaust valve guide replacement
The intake valve guide is not replaceable. If the intake valve guide
is worn beyond the service limit, replace the cylinder head.
1. Chill the replacement exhaust valve guide in the freezer section
of a refrigerator for about an hour.
2. Use a hot plate or oven to heat the cylinder head evenly to 150℃
(330℉)
Check the temperature with a temperature indicating stick
(available at welding supply stores) or equivalent.
Wear heavy gloves to prevent burns when handling heated cylinder
head.
Note
Do not use a torch to heat the cylinder head; warpage
of the cylinder head may result. Do not get the head
hotter than 150 °C (330 °F); excessive heat may loosen
the valve seats.
3. Remove the heated cylinder head from the hot plate and
support it with wooden blocks. Drive the exhaust valve guide
out of the head from the combustion chamber side.
Note
When driving the valve guide out, be careful not to damage
the head.
4. Remove the new exhaust valve guide from the refrigerator.
5. Install the new valve guide from the valve spring side of the
cylinder head. Drive the valve guide until the clip is fully seated
as shown.
6. After installation, inspect the valve guide for damage. Replace
the guide if damaged.
Service limit
0,10 mm
0,12 mm
45
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