Camshaft drive
| Camshaft drive |
| Camshaft assembly |
The engine has twin overhead camshafts with large base circle diameter cams, providing a high lift but little stress. The camshafts are driven by a timing chain equipped with a self- adjusting chain tensioner. The camshafts act directly on the valves via hydraulic tappets.
The hydraulic tappets adjust automatically to differences in valve clearance caused by temperature variations. They operate in an oil bath, with oil supplied via an oilway in the cylinder head. The main advantages of these hydraulic tappets are their near-silent operation and high degree of reliability.
The valves are made of steel and have chrome-plated stems. The heads of the exhaust valves are stellited.
| Chain tensioner |
Mounted in the cylinder head, the chain tensioner is easily accessible for service. Tensioning force is applied by a spring-loaded plunger which, via a guide bar pivoted at the bottom, keeps the slack side of the chain correctly tensioned. A ratchet with close-spaced teeth prevents the plunger, and with it the guide bar, from moving back.
Since the chain tensioner has close-spaced tensioning intervals, it provides good compensation for chain wear and consequently ensures quieter operation.
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