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Camshaft drive

Camshaft drive


Camshaft assembly

Each cylinder head has twin overhead camshafts having a large-diameter base circle, providing a large amount of lift but little stress. All four camshafts are driven by an internally-cogged belt with self-adjusting belt tensioner. The belt assembly also includes two adjustment rollers.

The camshafts are direct acting on the valves via hydraulic tappets. The hydraulic tappets adjust automatically to differences in valve clearance caused by variation in temperature. They operate in an oil bath, with oil supplied via an oilway in the cylinder head. The chief advantages of hydraulic tappets are that they are silent in operation and extremely reliable. In addition, each cylinder head has two air-purging nozzles to eliminate tappet noise after starting.

The valves have chromium-plated stems. The camshaft sprockets on the rear cylinder head are interchangeable as also are those on the front cylinder head.

Belt tensioner

Of dynamic and adjustable type, the belt tensioner is mounted on the slack side of the internally-cogged belt. Once belt tension has been adjusted, it tensions the belt continuously to compensate for belt wear.

The belt assembly also includes two adjustable rollers.