The Jaguar V12 engine is a V12 internal combustion engine produced by Jaguar Cars. The engine was based on a prototype design by Claude Baily for an intended Le Mans car—the Jaguar XJ13. The XJ13 project was terminated in 1966 before the car was ever entered into competition, but under the direction of Jaguar Chief Engineer William Heynes the V12 engine design was reworked by engineers Walter Hassan and Harry Mundy into a production-ready version, first installed in the Series 3 Jaguar E-Type of 1971. The V12 was the second production engine design in Jaguar's history. The all-aluminium block was fitted with removable wet iron liners, complete with single overhead camshaft aluminium heads with two valves per cylinder. It was regarded as one of the premier power plants of the 1970s and 1980s. Development Initial designs for a V12 engine were produced by engineer Claude Baily as early as 1951, with a view to using it in a Le Mans car. Baily's original 8.0 L design used double overhead camshafts heads sharing the same basic layout as the XK6 engine, in order to allow for a relatively high redline. Even after Jaguar withdrew from racing in 1957 the V12 design continued to be refined, and Baily proposed a range of displacements from 7.6 L (sharing 87 mm bore and 106 mm stroke measurements with the 3.8 L XK6) down to 5.0 L (sharing the 2.4 L XK6's 83 mm bore and 76.5 mm stroke). In 1962 Baily was instructed to begin prototype tooling and bench testing of a 5.0 L design, having settled on an 87 mm bore and 70 mm stroke. By 1964 several incarnations of the V12 engine were being tested, including versions meant for racing and others for installation into production cars. An all-aluminium quad-cam design with fuel injection was created for the XJ13, while cast iron blocks and heads, and other double and single overhead cam head designs were created for use in a production road car version. These production versions of the engine were tested in Mark X saloons. After the XJ13 project was cancelled the team of Hassan and Mundy designed a new single overhead cam head, with the camshaft lobes acting directly on vertically-inclined valves through bucket tappets. This was similar to the cylinder head design of the contemporary Rover 2000, with which the Jaguar V12 also shared the use of dished 'Heron'