Somerford Mini Ltd. Ordering Parts Using This Catalogue

External Engine - 998 and 1098cc
No. Part No. Description Qty. Remarks No. Part No. Description Qty. Remarks
998 and 1098cc Engine Identification
The 998cc A Series engine first saw Mini use in the Riley Elf and Wolseley Hor net Mk II models,
introduced in early 1963. By the end of 1963 they had been joined by the 998cc Mini Cooper, which
replaced the 997cc Cooper after a short production overlap. 1967 saw the first use of a 998cc engine
in a ‘standard’ Mini, the Mini Mk II 1000. This model, in both manual and automatic gearbox versions
and a wide range of trim levels and names, continued in production right the way through to 1992.
As with the 848cc engine, 998cc engines used with automatic gearboxes are different in several respects
to those used with manual. The Mini Clubman and Clubman Estate shared the Mini 1000’s power unit
until 1975, after which date the manual Clubmans received the 1098cc A Series (automatics continued
with 998cc, there being no automatic type 1098cc engine). While in 1980 the Clubman saloon was
dropped, the Estate continued for two years , badged ‘HL’ and reverting to 998cc in manual versions.
For 1981 the 998cc A Series engine was relaunched in A Plus specification, in readiness for what was
envisaged as a new and prosperous life in the Austin Metro (the Mini wasn’t expected to last much
longer by then!). The A Plus engine is most easily identified by the reinforcement ribs on the engine
block casting; these ribs are missing on the much smoother casting of the pre-A Plus unit. However, just
to confuse the issue, the A Plus components were actually introduced gradually between 1979 and 1981,
which means that many ‘hybrid’ engines were built at that time.
The Metro, overseas-built Mini Mokes and the very short-lived Allegro 3 are the only BMC/Leyland/Austin
Rover vehicles to share the use of the 998cc engine with the Mini.
The 1098cc engine first appeared in home market Minis in the aforementioned Clubman in 1975. The
only other UK-built Mini to receive the engine was the Special (1100) of 1979, a limited edition for the
20th anniversary of Mini production. The Special was heavily based on a similar Mini produced in
Belgium for mainland European markets , which also used the same engine. Through the 1970s and ear ly
1980s Europe always used the 1098cc A Series in Minis more than was the case in the UK.
In common with the 848 and 998cc engines, the 1098cc unit received a pad timing chain tensioner for
1979, with the tell-tale bulge on the timing cover. Not being destined for use in the Austin Metro, the
1098cc engine was not scheduled for the full 1981 A Plus improvement scheme; certain A Plus parts still
had to be used however because they were shared with 998cc engine production. The most obvious -
and biggest - example of this was the adoption of the A Plus ribbed cylinder block.
The best known of other 1098cc A Series applications was without doubt the best-selling BMC ADO16
range (Austin/Morris 1100, MG 1100, etc .). It is very possible if your Mini has received a 1098cc
upgrade that the engine started life in one of these cars, especially one of the very nice twin carburetter
versions. The only other transverse applications of the engine were o verseas-built Mokes (again) and
more basic trim level Austin Allegros . Non-transverse applications were le gion (Morris Minor, MG Midget,
etc.) but are of no consequence here: the engines cannot be made to sit on a Mini gearbox.
With the advent of 99H/ and 10H/ serial numbers , the codes became far more complex. 99H/ or 10H/
was followed by a three character code, either three digits (issued from 1967-81), or a letter and two
digits (1982 onwards). There were not many variations in the Mini 1098cc engine and most ha ve an
engine number beginning 10H/791. Engines with A Plus features star ted to appear around 10H/791/
180000, and the A Plus block was in use by 10H/791/217000.
Unfortunately there are too many combinations of 99H/ codes to list in the space available here, but if
you contact Somerford Mini with your full engine number we can ‘unpick’ the codes to tell you exactly
what specification your engine was built to. We can however give you two important developments later
in the life of the 998cc engine denoted by the codes, which mostly ran chronologically in numerical (and
from 1982 alpha-numerical) order:
99H/791/431856 Introduction of A Plus cylinder block (plus some engine numbers intermittently for a
short period beforehand;1980-90)
99H/997 Earliest code denoting complete A Plus specification engine (introduced 1980/81)
Additionally, it is helpful to know which A Plus 998cc engines are high (10.3:1) or low (8.3:1)
compression ratio, and which are lead-free engines:
High Compression Ratio:99H/997, 998, A53, A94, A98, B81, B82, C20, D80, D82
Low Compression Ratio: 99H/A19, A97, A99, B83, B84, B85, D83
Lead-Free High Compression Ratio: 99H/D81, E20, E21, F15, F16, F32, G30, G32, G33, G34, G39
Lead-Free Low Compression Ratio: 99H/960, A99, E22, G31
BMC/Leyland/Unipart/Rover Mini 998cc Manual (not Cooper) Reconditioned
Engine Part Numbers
8G31 998cc Wolsele y and Riley manual gearbox engine (1963-67; replaced b y 8G51)
8G47 998cc Wolsele y and Riley manual gearbox engine (1963-67; replaced b y 8G51)
8G51 998cc Wolsele y and Riley manual gearbox engine (1963-67)
8G56 998cc Austin, Morris, Wolsele y and Riley manual gearbox engine (1967-69)
8G57 998cc Austin, Morris, Wolsele y and Riley manual gearbox engine (1967-80)
GSE1102 998cc manual gearbox engine; ‘Gold Seal’ part no.Specification as 8G57 (1967-80)
RKM1102 998cc manual gearbox engine; ‘Silver Seal’ part no. Specification as 8G57 (1967-80)
RKM1119 998cc manual gearbox engine; later ‘Silver Seal’ part no. Replaced RKM1102 (1967-80)
8G63 998cc manual gearbox engine, Canada (1972-75)
BHM1061 998cc manual gearbox engine, Canada, Sweden and Japan (1975-80)
BHM1232 998cc A Plus manual gearbox engine, low compression (1980-85)
BHM1377 998cc A Plus manual gearbox engine, high compression (1980-85)
BHM1233 998cc A Plus manual gearbox engine, Japan (1980-85)
BHM1458 998cc A Plus manual gearbox engine, low compression (1985 on)
BHM1460 998cc A Plus manual gearbox engine, high compression (1985 on)
LBB10175 998cc A Plus manual gearbox engine, low compression, lead free (1988 on)
LBB10089 998cc A Plus manual gearbox engine, high compression, lead free (1988 on)
Engine serial number prefix codes are impor tant in identifying what you have in your car and
establishing which replacement parts to fit to it. The 998 and 1098cc engine number prefixes used on
Mini engines are listed here for that reason. The engine serial number is stamped on a plate affixed to
the cylinder head mating face or ‘deck’ of the cylinder block, at the front of the engine towards the right
hand side, as you look at the engine in the car. Note that the last code letter before the serial number
itself on pre-A Plus engines relates to the compression ratio of the engine: H for high compression, L for
low compression. A Plus high or low compression engines are by contrast identified by the letter plus
two digits part of the engine serial number prefix, a full list of these is shown below.
Factory reconditioned engines always lost their serial numbers in favour of an engine number plate
stamped with the appropriate part number for the intended application for each engine. In the absence
of an engine serial number on a factory reconditioned unit, this is the only means of identification - but
beware! Factory reconditioned engines were more often than not built up with whatever suitable
components were to hand; for example , new parts were usually plucked from the engine production line
and were therefore of the latest design. Reused components came from stocks of parts which would do
the same job, but were not necessarily the same design, all lumped to gether. In other words, parts used
in the rebuild were frequently incorrect historically for the engine being rebuilt.
998cc Wolseley and Riley Engine Serial Number Prefix Codes 1963-67
9WR/ Manual gearbox (direct change) engines (1963-64)
9AD/ Manual gearbox (remote change) engines without closed circuit breathing (1964-67)
9AE/ Manual gearbox (remote change) engines with closed circuit breathing (1964-67)
9AG/ Automatic gearbox engines without closed circuit breathing (1966-67)
9AJ/ Automatic gearbox engines with closed circuit breathing (1966-67)
998cc Cooper Engine Serial Number Prefix Codes 1963-69
9FA/SA Manual gearbox (3 Synchro) engine without closed circuit breathing (1963-64)
9FD/SA Manual gearbox (3 Synchro) engine with closed circuit breathing (1964-68)
9FD/XE Manual gearbox (4 Synchro) engine with closed circuit breathing (1968-69)
99H/377CHManual gearbox (4 Synchro) engine with closed circuit breathing and dynamo (1969)
99H/378CHManual gearbox (4 Synchro) engine with closed circuit breathing and alternator (1969)
BMC/Leyland/Unipart Mini 998cc Manual (Cooper)
Reconditioned Engine Part Numbers
8G33 998cc high compression, open circuit breathing, 12G206 cylinder head casting (1963)
8G34 998cc low compression, open circuit breathing, 12G206 cylinder head casting (1963)
8G40 998cc high compression, open circuit breathing, 12G295 cylinder head casting (1964)
8G39 998cc low compression, open circuit breathing, 12G295 cylinder head casting (1964)
8G42 998cc high compression, closed circuit breathing, 12G295 cylinder head casting (1964)
8G43 998cc low compression, closed circuit breathing, 12G295 cylinder head casting (1964)
8G49 998cc high comp., closed circuit breathing, 12G295 head, oil filter condition lamp (1964-69)
8G48 998cc low comp., closed circuit breathing, 12G295 head, oil filter condition lamp (1964-69)
GSE1103 998cc high comp.; ‘Gold Seal’part number. Specification approx. as 8G49 (1964-69)
RKM1103 998cc high comp.; ‘Silver Seal’ part number. Specification approx. as 8G49 (1964-69)
RKM1120 998cc high comp.; later ‘Silver Seal’ par t no. Replaced RKM1103 (1964-69)
BMC/Leyland/Unipart/Rover Mini 998cc Automatic
Reconditioned Engine Part Numbers
8G58 998cc Austin, Morris, Wolsele y and Riley automatic gearbox engine (1967-69)
8G59 998cc Austin, Morris, Wolsele y and Riley automatic gearbox engine (1967-80)
BHM1041 998cc Austin and Morris automatic gearbox engine (1974-80)
BHM1235 998cc A Plus automatic gearbox engine, low compression (1980-85)
BHM1378 998cc A Plus automatic gearbox engine, high compression (1980-85)
BHM1461 998cc A Plus automatic gearbox engine, high compression (1985 on)
LBB10088 998cc A Plus automatic gearbox engine, high compression, lead free (1985 on)
LBB10176 998cc A Plus automatic gearbox engine, low compression, lead free (1985 on)
BMC/Leyland/Unipart Mini 1098cc
Reconditioned Engine Part Numbers
BHM1042 1098cc manual gearbox engine, ‘Gold Seal’ (1975-80)
RKM1150 1098cc manual gearbox engine, ‘Silver Seal’ (1975-80)
BHM1229 1098cc manual gearbox engine with A Plus cylinder block, ‘Gold Seal’ (1980-81)
RKM1151 1098cc manual gearbox engine with A Plus cylinder block, ‘Silver Seal’ (1980-81)
998cc Wolseley and Riley Engine Serial Number Prefix Codes 1967-69
998cc Austin and Morris Engine Serial Number Prefix Codes 1967-69
998cc Mini Engine Serial Number Prefix Codes 1969-92
1098cc Mini Engine Serial Number Prefix Codes 1975-81
99H/ 998cc engines (1967-92)
10H/ 1098cc engines (1975-81)
Note that where no differentiation is made between open circuit or closed circuit breathing, or between
dynamo or alternator fitment, the factory instr ucted that the parts concerned (rocker cover, tappet cover,
pulley etc.) should be swapped over from the old engine to the new one as required.
Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk
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