Clean The Valves; Check Rods And Valve Guides - Nanni T4.155 Workshop Manual

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4. CLEAN THE VALVES

a. Use a gasket scraper to separate any accumulation of carbon
deposits on the tops of valves.
b. Use a metal brush to carefully clean valves.

5. CHECK RODS AND VALVE GUIDES

a. Measure the inside diameter of each valve guide using a
micrometer.
Guide inside diameter: 8.010 – 8.030 mm
b. Use a micrometer to measure the diameter of valve stems.
Valve stem diameter:
Intake : 7.975 – 7.990 mm
Exhaust: 7.960 – 7.975 mm
c. Subtract the measured value for the valve stem guide from the
value of the external diameter of the valve guide bush.
Nominal oil clearance:
Intake: 0.020 – 0.055 mm
Exhaust: 0.035 – 0.070 mm
Oil clearance limit:
Intake: 0.08 mm
Exhaust: 0.10 mm
If the oil clearance is greater than the maximum limit, replace the valve
and the guide bush involved.
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