Editing BMC B-series engine (section)

==Design==
[[File:Austin_A40_Engine_-_B-series_four_cylinder_(2566561210).jpg|left|thumb|A sectioned illustration of the Austin A40's 1200cc engine – the direct predecessor to the B series]]
The precursor of the "B" series engine was a 1200&nbsp;cc [[Overhead valve engine|Overhead Valve (OHV)]] engine which was used in the 1947-1952 [[Austin A40 Devon]], and, in slightly modified form, in the 1953 [[Austin A40 Somerset]]. This engine had many of the same basic dimensions as one of Austin's pre-war [[flathead engine|sidevalve]] engines - the 1125cc engine fitted in the [[Austin 10]] which had the {{convert|3.5|in|mm|1|abbr=on|order=flip}} stroke common to all later B-Series engines, allowing the use of much of the same installed equipment to produce the block and crankshaft - but to an all-new OHV design. Beyond this relationship to the pre-war Ten's engine, the lineage of the new OHV 1200cc power unit was somewhat complex - in the rest of its design it was in essence a scaled-down version of the 2199cc engine introduced in 1945 on the [[Austin 16 hp]].

The design of this unit were derived from the much larger OHV engine developed for the wartime [[Austin K5]] military truck, which used a 3995cc [[straight-six engine]] (minus two cylinders this engine became the 2660cc four-cylinder engine used in the [[Austin A90 Atlantic]] and the [[Austin-Healey 100]]). The K5 engine was broadly an Austin version of the 3519cc engine built by [[Bedford Vehicles|Bedford]] for its military trucks, and in turn the Bedford engine was similar in design to the [[Chevrolet Stovebolt engine#235|Chevrolet 235 straight-six engine]] - Bedford and Chevrolet both being part of [[General Motors]]. The common features found on all these engines, from the Chevrolet 235 to the Austin 1200cc, include the design of the valve gear and the cylinder head, especially the siamesed cylinder head ports.

The A40 engine was originally drawn up to be produced in two capacities of 990cc and 1200cc to fall into the Eight and Ten [[tax horsepower]] classes. Before the A40 was launched, the British government removed the tax horsepower system in favour of a flat tax rate making the smaller capacity redundant. Therefore, only the 1200cc version was built but could not be increased in capacity any further since it was already nearly at the maximum bore and stroke dimensions permitted by the design of the block casting. The long stroke, narrow bore characteristics of engines designed for the British taxation system remained.

Austin realised that eventually they would need an engine that could power many of its forthcoming medium-sized cars, and this would require an engine of at least 1500&nbsp;cc capacity. Since the A40 Devon engine could not have its capacity enlarged, a new engine needed to be designed and built.

The design of this new engine commenced around January 1952, and was designated as the "B" series. The first production version of the B series retained the same 1200cc capacity as the A40 engine and, superficially, appeared to be identical, with the same valve gear, same cylinder head design, same positioning of its ancillary parts (many of which were interchangeable with the older engine) and so on. But the B-series block and head were slightly larger in both length and width and the block had thicker cylinder wall castings making the new engine heavier than the A40 motor. This was to allow room for enlargement of the cylinder bore to provide the larger capacities foreseen by BMC.

The stroke was retained at {{convert|3.5|in|mm|1|abbr=on|order=flip}} and was never altered. Originally of approximately 1.2 Litre capacity, later displacements ranged widely from 1.2&nbsp;L to 2.4&nbsp;L, the latter being a six-cylinder variant which was only produced in Australia. The most common engine sizes were 1.5&nbsp;L and 1.8&nbsp;L and saw service in a number of vehicles. This included a version of the engine built under license in [[India]] by [[Hindustan Motors]] for its [[Hindustan Ambassador|Ambassador]] series of cars.<ref>Hindustan Ambassador. (webpage) Retrieved on 2 January 2016 from http://www.uniquecarsandparts.com.au/car_info_hindustan_ambassador.php</ref> [[Petrol]] versions were produced in the greatest numbers, but [[Diesel fuel|diesel]] versions exist for both cars and marine applications.

Meanwhile, the earlier 990cc displacement would later indirectly resurface in Japan from the late-1950s at Nissan after the company had engaged an American engine specialist called Donald Stone formerly of Willys-Overland as a consultant,<ref>{{cite book |last1=Halberstam |first1=David |title=The Reckoning |date=2012 |publisher=Open Road Integrated Media |location=New York |isbn=978-1453286104}}</ref><ref>{{cite book |title=Britain & Japan : biographical portraits. Vol. VI |date=2007 |publisher=Global Oriental Ltd |location=Folkestone, UK |isbn=978-9004217850 |pages=104–105}}</ref> Nissan was trying to develop a new 1-litre engine at the time for the 1957 [[Nissan Bluebird|Nissan Bluebird (210/211)]], but as Stone pointed out, it would have cost a fortune. His suggestion was to shorten the cylinder block of the 1.5-litre B-Series licence built in Japan as the [[Nissan H engine|1H engine]],<ref>{{cite book |last1=LONG |first1=BRIAN |title=DATSUN 240Z, 260Z & 280Z : fairlady roadster to 280zx. |date=2019 |publisher=VELOCE Publishing |isbn=978-1787115255}}</ref> thus the 1-litre [[Nissan C engine]] also known as the "Stone engine" was born being manufactured on Austin's old transfer machines. When it was later increased to 1.2-litres from 1958, it was named the [[Nissan E engine]].<ref>{{cite web |title=Tech Wiki - Datsun History : Datsun 1200 Club |url=http://datsun1200.com/modules/mediawiki/index.php?title=History#Engine_Technology |website=datsun1200.com}}</ref> This was followed by the [[Nissan J engine]], distinctly different from the earlier engines yet similar in many ways.<ref>{{Cite web
  |title=Austin A40 and A50
  |website=EarlyDatsun.com
  |url=http://www.earlydatsun.com/austina40a50.html
  |access-date=15 December 2014
  |archive-url=https://web.archive.org/web/20150208152243/http://earlydatsun.com/austina40a50.html
  |archive-date=8 February 2015
  |url-status=dead
}}</ref>

<!-- The design of the engine block and the method used to manufacture the [[crankshaft]] meant that it was much easier and more cost-effective to alter the capacity by changing the [[Bore (engine)|bore]] rather than the [[Stroke (engine)|stroke]]. This meant that the {{convert|3.5|in|mm|1|abbr=on|order=flip}} stroke of the B-Series, inherited from the pre-war Austin Ten engine, remained a constant on all variants of the engine, while the bore differed between capacities. This limitation was inherited by the engines which replaced the B-Series which were intended to use the same block tooling. Despite its very different internal architecture (with a [[heron cylinder head]] and siamesed bores) the [[BL O-series engine|British Leyland O-Series]] had the common stroke, as did its successors the [[Rover_M-series_engine|Rover M-]] and [[Rover T-series engine|Rover T-Series]] units. The O-Series also formed the basis of the [[Perkins Engines|Perkins Prima]] diesel engine, which was developed further into the [[Rover L-series engine|Rover L-Series]] diesel. For commonality of parts the L-Series' internal dimensions were carried over to the [[Land_Rover_engines#Td5_(engine_codes:_10P,_15P_and_16P)|Land Rover Td5]] unit developed in the late 1990s. This engine, still retaining the {{convert|3.5|in|mm|1|abbr=on|order=flip}} stroke introduced on the [[Austin 10|Austin Ten]] in 1932 and carried on through much of the post-war period by the B-Series, ended production in 2007 -->