Valve Spring: Testing and Inspection

Valve, Valve Spring and Valve Guide Inspection






NOTE: Two types of exhaust valve may be installed-standard valves A in illustration or carbon break valves-B in illustration. Carbon break valves may be identified by the machined profile C on the valve stem. To prevent exhaust valves *ticking, standard exhaust valves should be replaced with carbon break valves during engine overhaul.





1. Remove carbon deposits from exhaust valve guides using an 8.70 mm diameter reamer inserted from combustion face side of cylinder head.
2. Clean cylinder head, valve springs, valves and inlet valve guide bores. Ensure all loose particles of carbon are removed on completion.
3. Check existing valve stem and head diameters.
4. Check valve stem to guide clearance using new valves.





5. Renew valves and guides as necessary.
Valve Head Diameter A:
Inlet: 39.75 to 40.00 mm
Exhaust: 34.226 to 34.48 mm
Valve Stem Diameter B:
Inlet: 8.664 to 8.679 mm
Exhaust: 8.651 to 8.666 mm
6. Check installed height of each valve.
Valve Installed Height C: 47.63 mm
7. Renew valve/valve seat insert as necessary.
8. Check valve stem to guide clearance.
Valve stem to guide clearance D:
Inlet: 0.25 to 0.66 mm
Exhaust: 0.38 to 0.78 mm
9. Check condition of valve springs:
Free Length: 48.30 mm
Fitted Length: 40.40 mm
Load-Valve Closed: 339 ± 10 N
Load-Valve Open: 736 ± 22 N

NOTE: Valve springs must be replaced as a complete set.