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Camshaft drive

Camshaft drive


Camshaft and tappets

The engine has twin overhead camshafts driven by a timing chain equipped with a self-adjusting chain tensioner. The camshafts act directly on the valves via hydraulic tappets which adjust automatically to differences in valve clearances caused by temperature variations. They operate in an oil bath, with oil supplied via an oilway in the cylinder head. The valves are made of steel with 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.