View source for BMC B-series engine

{{Use dmy dates|date=December 2016}}
{{Use British English|date=December 2016}}
{{Infobox automobile engine
|image = BMC B-Series engine.jpg
|name = B-series engine
|manufacturer = [[British Motor Corporation|BMC]]
| designer = [[Leonard Lord]], John Rix, Eric Bareham
|configuration = [[Inline-four engine|Inline-4]] and [[Straight-6 engine|Inline-6]]
|production = 1954–1986
|predecessor = [[BMC A-Series engine]]
|successor = {{ubl|[[BMC E-Series engine|BMC E-Series]]|[[BL O-Series engine|BL O-Series]]}}
|bore = {{ubl|{{convert|65.5|mm|in|1|abbr=on}}|{{convert|73|mm|in|1|abbr=on}}|{{convert|75.4|mm|in|1|abbr=on}}|{{convert|76.2|mm|in|1|abbr=on}}|{{convert|80.2|mm|in|1|abbr=on}}}}
|stroke = {{convert|89|mm|in|1|abbr=on}}
|displacement = {{ubl
  | [[Straight-four engine|Inline-fours]]: 
  | {{convert|1199.6|cc|L|1|order=flip|abbr=on}} 
  | {{convert|1490|cc|L|1|order=flip|abbr=on}} 
  | {{convert|1588|cc|L|1|order=flip|abbr=on}} 
  | {{convert|1623|cc|L|1|order=flip|abbr=on}} 
  | {{convert|1762|cc|L|1|order=flip|abbr=on}} 
  | {{convert|1798|cc|L|1|order=flip|abbr=on}}
  | [[Straight-six engine|Inline-six]]: 
  | {{convert|2433|cc|L|1|order=flip|abbr=on}} 
}}
|length =
|width =
|height =
|weight =
|block = Cast iron
|head = {{ubl|Cast iron|[[Aluminum alloy]] (Twin-Cam)}}
|valvetrain = [[Overhead valve engine|OHV]], [[DOHC|Twin-Cam]]
|fuelsystem = Single or twin [[carburettor]]s
|fueltype = [[Petrol engine|Petrol]] & [[Diesel engine|Diesel]] versions
|oilsystem =
|coolingsystem = [[Radiator (engine cooling)|Water-cooled]]
|power ={{convert|39-108|bhp|kW|abbr=on}}
|torque ={{convert|64|lbft|abbr=on}}
|compression =8.3:1-9.9:1
|fuelcon =
|specfuelcon =
|oilcon =
}}

The '''BMC B series''' is a line of [[straight-4]] & [[Straight-six engine|straight-6]] [[internal combustion engine]] mostly used in [[automobile|motor cars]], created by British automotive manufacturer [[Austin Motor Company]].

==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 -->

==Construction==

The engine was of conventional construction with a one-piece [[crankcase]] and [[cylinder block]] in cast iron with the crankcase extending down to the lowest level of the [[main bearing]] caps; with a [[cylinder head]], also usually in [[cast iron]], and a [[Wet sump|sump]] made from pressed [[steel]] for rear-wheel drive vehicles. Early engines used a three-[[Bearing (mechanical)|bearing]] [[crankshaft]], but later engines used five bearings. On all except the rare twin overhead [[camshaft]] variant, the camshaft — which was chain driven and mounted low in the block — operated the overhead valves via [[pushrod]]s and [[rocker arm]]s. The two inlet ports in the [[Reverse-flow cylinder head|non-crossflow cylinder head]] were shared between cylinders 1 + 2 and 3 + 4 and the three [[exhaust port]]s between cylinder 1, 2 + 3 and 4. [[Valve]] clearance was adjustable by screws and locknuts on the rocker arms.<ref>Austin Motor Company. ''Austin A40 Models Service Manual''. Austin, Birmingham, UK.</ref> Another unconventional characteristic of the engine is that the bore spacing is not constant between all four bores. The distance from cylinder 1 to 2 is 3.4375"; 2 to 3 =3.875"; and 3 to 4 =3.4375".

The B series shares many design features (such as the heart-shaped [[combustion chamber]]s and siamese inlet ports designed by [[Weslake|Harry Weslake]]), as well as its basic layout and general appearance, with the smaller [[BMC A-series engine]]. However another difference was its block's full-depth skirt which provided excellent bottom-end strength. This made the engine highly durable and suitable for developing into diesel versions in later years.

==Engine types==

==={{vanchor |1.2}}&nbsp;litre engines===
The {{convert|1199.6|cc|L|1|order=flip|abbr=on}} version was the first version of the engine. The bore and the stroke was {{convert|65.5x89|mm|in|abbr=on}}. The maximum power output was {{convert|39|bhp|kW|abbr=on}} at 4300&nbsp;rpm.

After the formation of [[British Motor Corporation]] (BMC) the new B Series engine was used in the following vehicles:

*1954–56 [[Morris Cowley]]
*1954–56 [[Austin Cambridge|Austin A40 Cambridge]]
*1954–55 [[Nash Metropolitan]] 1200 (used unique "2G" engine prefix)
*[[Massey-Harris]] Combine Harvester

==={{vanchor |1.5}}&nbsp;litre engines===
[[File:Nash Metropolitan Series 3 Austin 1500 engine.jpg|right|thumb|250px|B-series 1500 engine in a [[Nash Metropolitan]] Series 3]]

The {{convert|1489|cc|L|1|order=flip|abbr=on}} version was first used in 1953 in the [[MG Magnette]] ZA in twin [[carburettor]] version and in 1954 in the [[Morris Oxford Series II]] and [[Austin Cambridge]].<ref>Lost Marques;Morris-The William Morris Story. (webpage) Retrieved on 1 January 2016 from http://www.uniquecarsandparts.com.au/lost_marques_morris.php</ref> In 1957, it was used in the original [[MG MGA|MGA]]. Output in twin carburettor form was {{convert|68|-|72|bhp|kW|abbr=on}} and {{convert|55|bhp|kW|abbr=on}} with a single carburettor. Bore and stroke was {{convert|73x89|mm|in|abbr=on}}.

There was also a diesel version of this engine size. Power output was {{convert|40|bhp|kW|abbr=on}} at 4,000&nbsp;rpm and [[torque]] {{convert|64|lbft|abbr=on}} at 1,900&nbsp;rpm. The 1.5&ndash;litre diesel engines were made in India by [[Hindustan Motors]] for many decades until the production of the [[Hindustan Ambassador|Ambassador]] was phased out in 2013. They are very popular amongst the taxicab market in India even today. This engine was also license built by Nissan in Japan in the late 1950s as the [[Nissan H engine#1H|1H engine]].

The 1.5 B-Series would also form the basis of the 1958 [[Perkins Engines|Perkins]] 4.99 / 1.6 L (1,622 cc) diesel, which was fitted in cars, boats and commercial vehicles including London Taxis like the [[William Beardmore and Company|Beardmore Mk7 Paramount taxi]], [[Ford Thames 400E]], early [[Ford Transit]]s, [[Bedford CA]], [[Vauxhall Victor]],<ref>{{Cite web|url=https://www.curbsideclassic.com/curbside-classics-european/carshow-classics-1957-to-1972-vauxhall-victor-luton-salutes-the-victor/|title = Carshow Classics: 1961-1972 Vauxhall Victor – Luton Salutes the Victor|date = 26 July 2020}}</ref> [[Hillman Minx]],<ref>{{Cite web|url=https://www.motorsportmagazine.com/archive/article/january-1960/34/rumblings-january-1960|title = Rumblings, January 1960 | date=7 July 2014 }}</ref> [[Standard Ensign]] and [[Moskvitch 402|Moskvitch 407]]. In the mid-1960s the 4.99 was upgraded to become the 4.107 / 1.8 L (1,760 cc) and later the classic 4.108 / 1.8 L (1,760 cc), powering the [[Bedford CF]], [[Commer FC]], [[Alfa Romeo Romeo|Alfa Romeo F12/A12]], [[Alfa Romeo Giulia]], [[SEAT 131]] and [[Moskvitch 408]] as well as being used extensively in marine applications, farm equipment and Mustang/OMC skid-steer loaders. The 4.108 continued in production until 1992 the last application being for the auxiliary power unit fitted on British Army tanks in the Gulf War to power the essential air conditioning equipment. A total of almost 500,000 engines were made in Peterborough, with small numbers built elsewhere from kits. The peak production volume was reached in 1970, when almost 30,000 were made.<ref>{{cite web |url=https://sites.google.com/view/perkinslongserviceclub/heritage-snippets/the-4-99-4-107-4-108-engines |title=The 4.99, 4.107, 4.108 engines |website=Perkins Long Service Club |access-date=29 June 2022 }}</ref>

{{hidden begin
|title      = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle  = text-align:left;
}}
*1954–61 [[Morris Oxford Series II]], [[Morris Oxford Series III|III]], [[Morris Oxford Farina|V & VI]]
*1956–59 [[Morris Cowley]]
*1956–62 [[Nash Metropolitan]] 1500
*1955–58 [[MG MGA|MGA]]
*1953–61 [[MG Magnette]] ZA, ZB, & Mark III
*1956-61 [[Morris Commercial J2|Morris J2]] 1/2-ton vans
*1956–58 [[Austin Cambridge|Austin A50 Cambridge]]
*1958–61 [[Austin Cambridge|Austin A55 Cambridge]]
*1956–58 [[Wolseley 15/50]]
*1957–65 [[Wolseley 1500]]
*1958–61 [[Wolseley 15/60]]
*1957–61 [[Morris Commercial JB-type]] half-ton vans
*1957-61 ((Austin 101)) half-ton vans
*1957–65 [[Riley 1.5]]
*1959–61 [[Riley 4/68]]
*1959–65 [[Rochdale Olympic]]
*1958–62 [[Morris Major]] and [[Austin Lancer]] Series I/II
*1957–63 Tempo Matador
*[[Hindustan Ambassador]]
*[[Hindustan Contessa]]
*[[International Harvester]] "Metro-Mite" delivery truck
*Navigator 1500 [[Marine propulsion|marine engine]]
*1958–60 [[TVR Grantura]] Mark I
*1960–62 [[TVR Grantura]] Mark II & IIA
*1958–59 [[Elva (car manufacturer)|Elva Courier]]
{{hidden end}}

==={{vanchor |Twin-Cam}} engines===
A special Twin-Cam ([[DOHC]]) version of the {{convert|1588|cc|L|1|order=flip|abbr=on}} B-series engine was produced for the [[MG MGA|MGA]]. Output was {{convert|108|bhp|kW|abbr=on}} at 6700&nbsp;rpm in the high-compression (9.9:1) version and {{convert|100|bhp|kW|abbr=on}} in the optional low-compression (8.3:1) version. The engine block was cast iron, but the crossflow eight-port cylinder head was of [[aluminium alloy]]. Drive to the twin camshafts was by chain from a [[Gear train|gear-driven]], half-speed shaft running in the space that would have been occupied by the conventional camshaft.

This engine gained a reputation for being unreliable in service, especially in the high-compression version which needed high-[[octane]] fuel, but this has now been largely overcome. The piston burning habits — thought to be the result of [[ignition timing]] — was later discovered to be due to a vibration induced lean burn situation involving the float bowls, easily correctable by flexibly mounting the carburettors. A total of 2,111 cars were built, in both [[coupé]] and [[Roadster (automobile)|roadster]] versions.

A very few engines with the special displacement of {{convert|1762|cc|L|1|order=flip|abbr=on}} were produced for racing purposes.

Applications:
*1958–60 [[MG MGA#Twin-Cam|MGA Twin-Cam]]

==={{vanchor |1.6}}&nbsp;litre engines===
The engine was enlarged to {{convert|1588|cc|L|1|order=flip|abbr=on}} in 1958 by increasing the bore to {{convert|75.4|mm|in|abbr=on}}.

Applications:
*1959–61 [[MG MGA|MGA 1600]]
*1960–62 [[TVR Grantura]] Mark II, IIA
*1959-61 [[Elva (car manufacturer)|Elva Courier]] Mark II

===1.6&nbsp;litre {{vanchor |Mark II}} engines===
The engine was enlarged to {{convert|1622|cc|L|1|order=flip|abbr=on}} in 1961 with another bore increase, this time to {{convert|76.2|mm|in|abbr=on}}.

{{hidden begin|title=Applications:|titlestyle=background:#88FF88; text-align:left;|bodystyle=text-align:left;}}
*1961–62 [[MG MGA|MGA Mark II]]
*1961–69 [[Austin Cambridge|Austin Cambridge A60]]
*1961-67 [[Morris Commercial J2|Morris J2]] 1/2-ton vans
*1961–71 [[Morris Oxford Farina#Oxford series VI (1961–1971)|Morris Oxford VI]]
*1961–71 [[Wolseley 15/60|Wolseley 16/60]]
*1961–69 [[Riley 4|Riley 4/72]]
*1961–68 [[MG Magnette|MG Magnette Mark IV]]
*1961–67 Austin 152 & [[Morris J2]] 1/2-ton van
*1974–78 [[LDV Pilot|Sherpa van]]
*1962–64 [[Morris Major]] Elite
*1963–66 Tempo Matador
*1966–67 Hanomag Matador
*1967–73 Hanomag F20, Hanomag F25, Hanomag F30, Hanomag F35
*1970–73 Mercedes-Benz L206, Mercedes-Benz L306
*Navigator 1600 marine engine
*1962–64 [[TVR Grantura]] Mark III
*1963-64 [[Elva Courier]] Mark III
{{hidden end}}

{{anchor |Blue Streak|I6}}
The {{convert|1622|cc|L|1|order=flip|abbr=on}} B series also formed the basis of the "Blue Streak" engine developed by [[British Motor Corporation (Australia)|BMC Australia]] for use in the locally-built [[Austin Freeway]] and [[Wolseley 24/80]] models, both in turn variants of the existing Austin A60 Cambridge. The "Blue Streak" was an inline-6 development of the B series, adding two extra cylinders to create a {{convert|2433|cc|L|1|order=flip|abbr=on}} engine. Different market demands in Australia required the fitting of a six-cylinder engine to a car the size of BMC's mid-range [[British Motor Corporation#BMC Farina|Farina]] model and the corporate [[BMC C-Series engine|C-series engine]] would not fit, requiring the development of the unique "Blue Streak" engine. Both models were withdrawn in 1965 and no further use of the engine was made.

==={{vanchor |1.8}}&nbsp;litre engines===
The engine was enlarged again to {{convert|1798|cc|L|1|order=flip|abbr=on}} in 1962. Bore was {{convert|80.2|mm|in|abbr=on}} and stroke was still {{convert|89|mm|in|abbr=on}}, power varied by application with typically {{convert|94|bhp|kW|abbr=on}} at 5,500&nbsp;rpm in twin carburettor format and {{convert|85|bhp|kW|abbr=on}} in single carburettor format as used in the [[Morris Marina]].<ref>{{cite web|last1=Zal|first1=Pawel|title=1972 Morris Marina Coupé|website=Automobile-Catalog.com|url=http://www.automobile-catalog.com/make/morris/marina/marina_coupe/1972.html|access-date=25 February 2017}}</ref> The engine at first had a three-bearing crankshaft with a five-bearing version appearing in 1964.

There was also a diesel version of this capacity, used in the [[Leyland Sherpa]] van with a power output of {{convert|56|bhp|kW|abbr=on}} at 4,250&nbsp;rpm, and built under license in [[Turkey]] for many years. It is still widely used on narrowboats on the canals of the UK.{{citation needed|date=March 2014}}

{{hidden begin
|title      = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle  = text-align:left;
}}
*1969 [[Probe 16]]
*1962–80 [[MG MGB|MGB]]
*1964–75 [[BMC ADO17]] ("Landcrab") Austin 1800
*1967–72 [[BMC ADO17]] ("Landcrab") Wolseley 18/85
*1966–75 [[BMC ADO17]] ("Landcrab") Morris 1800
*1975–78 [[Princess (car)|Princess]] 1.8
*1971–78 [[Morris Marina]] 1.8
*1964–67 [[TVR Grantura]] Mark III and IV
*1964-65 [[Elva Courier]] Mark IV
*1974–78 [[Leyland Sherpa]] van
*1973–75 [[Hanomag]] F20, Hanomag F25, Hanomag F30, Hanomag F35 ([[:de:Harburger Transporter|de]])
*1973–77 Mercedes-Benz L207
*1973–78 Mercedes-Benz L307
{{hidden end}}

==={{vanchor |2.0}}&nbsp;litre engines===
2-litre B-Series prototype was designed by BMC engine-man Stan Johnson in 1964–65. This unit displaced 1,998 cc, power output was 106&nbsp;hp and featured siamesed cylinder bores and offset conrods in order to use the existing 1.2/1.5-litre cylinder block. This engine never went beyond the prototype stage.<ref>{{Cite web|url=https://www.leylandprincess.co.uk/o-series.htm|title = O-Series engines|url-status=dead|archive-url=https://web.archive.org/web/20211027035642/https://www.leylandprincess.co.uk/o-series.htm|archive-date=27 October 2021}}</ref>

==={{vanchor |2.4}}&nbsp;litre engines===
There was a {{convert|2433|cc|L|1|order=flip|abbr=on}} six-cylinder unit, named "Blue Streak", which was used in the Australian [[Austin Freeway]] and [[Wolseley 24/80]].

==Engine numbering==
There were two series of engine numbers used; BMC changed the system at the end of 1956.<ref name=number>MG Car Club. Engine Codes (webpage) Accessed on 1 January 2016 from http://www.mg-cars.org.uk/news/news498.html</ref>

===Numbering system, 1936 to 1956===
As an example numbers were of the style "BP15GB" followed by the engines serial number, where:

*BP = '''B''' series engine with '''P''' for pushrod (Overhead Valve)
*15 = capacity
*G = MG (for full list of codes see reference below)
*B = This final letter denotes the engine version.

===Numbering system, 1957 to 1970===
As an example numbers were of the style "15GB-U-H" plus a serial number, where:

*15 = capacity
*G = MG (other letters were: A = Austin, B = Industrial, H = Miscellaneous, J = Commercial, M = Morris, R = Riley, V = Vanden Plas and W = Wolseley )
*B = B series engine
*U = Central gear change (other letters were: A = Automatic, M = Manumatic clutch, N = Column change, O = Overdrive, P = Police, DA = Close ratio gearbox. Note letter A is in a smaller font size).
*H = High compression (alternatively L = Low compression)

===Numbering system, 1970 onwards ===
Beginning in the early 1970s the numbering system was simplified to "18 V" plus a serial number, where 18 represents the capacity and V = vertical, ''i.e.'' longitudinal (in-line, not vee-arranged) engine with [[rear-wheel drive]], and H = Horizontal, ''i.e.'' transverse engine with [[front-wheel drive]].<ref name=number />

There was sometimes a country indicator after the first part of the code, ''e.g.'' "18V-Z" was used for some [[United States]] (except [[California]]) [[MG MGB]] engines.

==See also==
*[[BMC A-series engine]]

==References==
{{reflist}}
*{{cite book |title= BMC and Leyland B-Series Engine Data|last=Porter |first=Lindsay|year=1985 |publisher=Osprey|isbn=0-85045-597-9}}

==External links==
*[http://www.mg-cars.org.uk/news/news498.html List of engine codes]
*[https://web.archive.org/web/20070311055719/http://www.austin-rover.co.uk/index.htm?enginebseriesf.htm B series engine description at "the unofficial Austin Rover resource"]
*[https://web.archive.org/web/20190531093554/https://sites.google.com/site/perkinslongserviceclub/heritage-snippets/the-story-of-the-4-99-4-107-4-108-engine "Perkins - Heritage Snippets - The story of the 4.99 / 4.107 / 4.108 Engine"]

{{DEFAULTSORT:BMC B-Series engine}}
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