Standard wet liner inline-four engine

The Standard wet liner inline-four engine was an inline four cylinder petrol engine produced by the Standard Motor Company. Originally developed concurrently for passenger car use and for the Ferguson TE20 tractor, it was widely used for Standard passenger cars of the 1950s, most notably the Vanguard. Later it was successfully used in Standard's popular early generation Triumph TR series sports cars.

The water-cooled overhead valve engine featured novel advances for an immediate post-war design, which included thin-wall bearings with replaceable shells and loose-fitted wet liners. Displacement varied from 1,850 cc to 2,088 cc (and 2,188 cc in a tractor variant), growing with time.

The engine's origins lay in the wartime production of Bristol aero engines at the new Banner Lane shadow factory, operated by Standard in Coventry. From 1939 this factory produced Bristol Hercules engines, an air-cooled radial engine, with Bristol's typical sleeve valves. With peace in 1945, this huge factory then stood empty.

During the war, Ford had built tractors for Ferguson in Detroit. Afterwards, Ferguson wished to continue this arrangement with an improved TO20 tractor (for "Tractor Overseas") and also a TE20 (for "Tractor England") to be built by Ford's plant at Dagenham. Ford however was unwilling and it was Standard which was to build the tractors at Banner Lane. The first TE20 model used a Continental Z-120 petrol engine, but the TE-A20 and later models used a new engine developed by Standard.

The new tractor engine appeared in 1947. It was a petrol powered four-cylinder engine with a bore of 80 mm and stroke of 92 mm, for a total capacity of 1,850 cc. The engine was undersquare (long stroke), favouring the tractor's need for torque over horsepower and the British practice of building long stroke engines, dictated by the tax horsepower regulations. A compression ratio of 5.77:1 reflected the era's low octane fuel. Conventional overhead valves were driven from a camshaft mounted in the side of the cylinder block via vertical pushrods and adjustable rockers. Cylinder block and crankcase were one piece cast iron, as was the cylinder head. The crankshaft had three main bearings typical of 4 cylinder engines of the era.

Construction of the engine would be regarded as typical for the 1950s, although this engine was developed in the late 1940s and its lineal derivatives, the Triumph straight-four and straight-six engines, would remain in production into the 1970s. In some aspects it was advanced for its day, particularly in its use of components such as pistons being pre-graded into standardised sizes and marked as such. This avoided the need for costly hand-fitting during assembly and also simplified replacement in service. It was one of the first mass-production engines to use thin-wall bearings: a steel shell faced with whitemetal bearing material. Rather than re-metalling the bearing journals and hand-scraping a new bearing surface to fit the crankshaft, these bearings were disposable after use. Several replacement bearing shells were expected to be fitted before the crankshaft required re-grinding. Had the tractor been built at Ford, Dagenham as originally intended, it is likely that the engine would still have been designed around the whitemetal bearings that Ford continued with on small car engines throughout the 1950s.

The distinctive, and unusual, feature of the engine was its use of wet liners to form the cylinders. Rather than the cylinders being bored into the cast-iron block, separate thin-walled steel tubes were inserted into a hollow block. The space between liner and block formed a large uninterrupted water jacket, which improved cylinder heat dispersal into the cooling system, as did the thin tubes of the liners. The liners were only loosely installed into the block with hand pressure. The sealing of the liners into the engine block was at the bottom by a pair of soft metal "spectacle washers" that each sealed a pair of liners. Each liner stood slightly proud of the cylinder block face. so that it formed a good seal against the head gasket when assembled. Such wet liners had been used in high performance engines for many years, but this was an early example of them for a low-cost, mass-production engine. Particularly with the advanced grinding techniques necessary to make such a thin-walled tube with good concentricity and surface finish, other manufacturers saw them as over-complex. However Banner Lane's building of sleeve-valve Bristol engines during the war had given them the necessary experience and equipment. Throughout the engine's service it was seen as a dependable and reliable engine, if slightly staid and tractor-like. The liners never gave the trouble experienced by other engines such as the much later Rover K-series.

Another distinctive, although less revolutionary, feature of the engine was the location of the tubes carrying the valve pushrods. Rather than being cast inside the cylinder head, thus requiring more cores and complexity, they were outside the main casting of the cylinder head. The top and bottom faces of the cylinder head were extended to form a flange on the camshaft side of the engine with individual steel tubes placed through the flanges to enclose each pushrod (a similar system was used for the Volkswagen Beetle engine, albeit with longer tubes the entire length of the cylinder). These tubes were expanded at top and bottom to seal them and thus became a permanent part of the cylinder head. The separate tubes were reliable, less expensive to manufacture than casting them into the head, and gave that side of the engine its distinctive "hollow" appearance with the rocker box appearing to be supported by columns.