1962 a larger Twin Cam appeared in the just-released Giulia. The obvious change was that displacement was increased to , but the engine was also now being produced using a different casting method. The diameter of the valve stems had been increased by , the bore centre spacing was different, the timing chain longer and the crankshaft had been revised, among other changes. In 1968 the engine was again enlarged, this time to , for the 1750 GTV and 1750 Berlina. Additional changes to this version included offsetting the big-end bearings on the connecting rods, and adding sodium-filled exhaust valves. In 1971 a version was introduced for the 2000 GTV and 2000 Berlina. This largest production Twin Cam also had fewer teeth in the ring-gear and 6 bolts holding the flywheel instead of 8. When the engine was adapted for use in the Alfetta in 1972, this necessitated a new oil pump and a change away from the finned sump used in the 105-series cars. While this was an aesthetic loss it may have been beneficial in other ways, as some owners reported that the old sump kept the engine and oil so cool that in cold weather it was sometimes necessary to block off the radiator airflow to raise the coolant temperature enough for the interior heater to be effective. Since the Alfetta also used a rear-mounted transaxle, there was no need for a pilot bearing in the engine. The Twin Cam was the first production automobile engine to employ a form of Variable Valve Timing (VVT). The system that appeared on the 1980 Spider was an electro-mechanical system employing a variator to alter the phase but not duration of the intake camshaft. Competition variations and specials Alfa Romeo's Autodelta competition arm produced a multiplicity of variations on the Twin Cam for different racing classes and cars including the racing oriented GTA. Displacements ranged from a over-square version with a bore and stroke of up to a version with a bore and stroke of . Many of these engines used dual ignition systems (see "Twin Spark"). Even though Alfa Romeo never sold a production version of the Twin Cam with more than 8 valves, at least two 16 valve cylinder heads were available. A number of Autodelta engines had them, and another 16-valve head was developed by the tuner Franco Angelini. Some Autodelta cylinder heads had an included angle