Description And Operation: Engine: Description: Camshafts

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

The engine is fitted with a Double Over Head Camshaft (DOHC) configuration which uses two camshafts, one intake and one exhaust. The lobes on the camshafts control the opening and closing of the valves via a roller finger cam follower valve train system.

The camshafts run on needle roller bearings to reduce friction and minimize the breakaway torque on engine startup. The needle roller bearings are housed in the camshaft carrier and the camshaft caps are marked with 'I' and 'E' to denote intake and exhaust. The camshaft caps are also numbered to ensure assembly in the correct position in the camshaft carrier. For example 'I4' or 'E1'.

The camshafts are of a hollow steel tube construction, with pressed on sintered lobes and needle roller bearings. The hollow tube design provides reduced weight for increased engine performance. Each camshaft has a pressed on drive adapter which locates a drive sprocket on the intake camshaft and the Variable Camshaft Timing (VCT) actuator on the exhaust camshaft. The drive adapter on each camshaft is fitted with a timing pin to locate the drive sprocket and the VCT actuator on the camshaft relative to the lobe positions. The exhaust camshaft has a pressed on reluctor ring for use with the Camshaft Position (CMP) sensor.

The exhaust camshaft is fitted with a VCT actuator. The actuator contains a sprocket which drives the camshaft via a timing chain, driven from the crankshaft. The VCT actuator adjusts the timing of the exhaust camshaft, increasing engine efficiency and performance as required. A reluctor wheel is pressed on to the opposite end of the exhaust camshaft which is monitored by the CMP sensor. The CMP sensor signal is used by the Powertrain Control Module (PCM). The CMP sensor enables the PCM to determine the position of the exhaust camshaft. The exhaust camshaft can then be phased by the VCT actuator to provide increased performance and efficiency.