If you have the engine tag still attached to the engine - just in front/below the thermostat housing - or perhaps the original engine number in the log book then the following should help you determine which engine you have. For Metro units, see 'Engine - Metro identification data'.

Original engine identification numbers

850cc
8A Austin up to 25000
8MB Morris up to 25000
8AM Austin & Morris 25000 onwards
8AH Austin & Morris Automatic
8AJ Austin & Morris closed circuit breathing
8AK Austin & Morris automatic with closed circuit breathing
8WR Wolseley Hornet & Riley Elf
8AC Moke
85H/101 All variants 1969 onwards

Note: third suffix letter denotes compression type, L = Low, H = High, e.g. 8AM/U/H101 denotes high compression.

998cc
9WR Wolseley Hornet & Riley Elf Mk2, pre closed circuit breathing
9AD Austin, Wolseley Hornet & Riley Elf Mk2 with remote type gearbox and closed
circuit breathing
9AE Wolseley Hornet & Riley Elf Mk3
99H/-/101 on Wolseley, Riley, Mini 1000, Clubman1000 1970 onwards and Mk3 with dished
piston
99H/791 Mini 1974 onwards with dished piston
99H/997 1980 onwards A+ block, flat top psitons, economy fitment with 2.95 final drive
99H/A97P A+ block with dished pistons, pre-A+ gears, 3.44 final drive & 12-inch wheels

998 A+ block with centre locating tang in main cap, 1985 onwards
Flat top piston with circlip wrist pin retention
99H/B81 Up to engine number 127431
99H/C20 Up to engine number 105023
99H/997 From engine number 127422 with 2.95 final drive
99H/A35P

Flat top piston with press fit wrist pin
99H/B81 From engine number 127432
99H/C20 From engine number 105024
99H/D80

Flat top pistons with press fit wrist pins, Lead-free cylinder head
99H/G30 or G32 or G33
99H/F15 or F16
99H/E20 or E21
99H/D81
LBB10089

Dished pistons with circlip wrist pin retention
99H/B83P Up to engine number 102908
99H/B84P Up to engine number 100216

Dished pistons with press fit wrist pin
99H/B83P From engine number 102909
99H/B84P From engine number 100217

Dished pistons with press fit wrist pin, Lead-free
99H/G31
99H/E22
LBB10175

1100cc (1098cc)
10AMW/Ta Clubman Estate and Austin 110 (ADO16 shape)
10H791 Clubman saloon
10H/-/H All Austin 1100 2 & 4 door derivative Saloons (ADO16 shape)
10GR/Ta/H MG1100 (ADO16 shape)
10GRB/Ta/H MG1100 & Wolseley 1100 (ADO16)
10V/Ta/H Vanden Plas 1100 (ADO16 shape)

997 Cooper
9F/Sa/H101 to 2637 except 19201 to 20410 (became 1070S)

998 Cooper January 1964 onwards)
9FA/Sa/H Mk1 Austin pre closed circuit breathing
9FD/Sa/H Mk1 Morris up to engine number 1934, all Austin Mk2 closed circuit breathing and
Morris Mk2 from engine number 1935-33660 with closed circuit breathing
9FD/Xe/H 4 syncro gearbox introduced
99/-/H Last of manufacture 1969

Cooper S variants
970cc
9F/Sa/X Engine numbers 29001-29003 with Tecalamit filter
9FD/Sa/X Closed circuit breathing introduced with Tecalamit filter
9FE/Sa/X Closed circuit breathing, oil filter with oil light switch introduced
9F/Sa/X Engine numbers 29039-30029 Purolator oil filter with oil light switch and closed
circuit breathing
1070cc
9F/Sa/H Engine numbers 26501 to 33660 and 19201 to 20410
9FD/Sa/H Engine numbers 33661 to 33948 with closed circuit breathing and oil light switch in
oil filter head
1275cc
9F/Sa/Y Engine numbers 31001 to 31504 pre closed circuit breathing with Purolator oil filter
9FD/Sa/Y Closed circuit breathing with oil light switch on filter housing after engine number
32178
9FE/Sa/Y Closed circuit breathing with oil light switch on Purolator filter housing and piston
design change
9F/Sa/Y From engine number 32378 onwards, cosed circuit breathing with Purolator filter
with oil light switch, Aeg510 camshaft introduced at engine number 40006, cross-
drilled EN40Bcrank at engine number 42730 and metal dipstick tube at engine
number 42548 onwards
12H397 Cooper S Mk3 with dynamo, negative earth and Tuiftrided EN16T crankshaft
12H398 Cooper S Mk3 with alternator, negative earth and Tuftrided EN16T crankshaft

Note: Only Cooper S engines with prefix '9F' had EN40B forged steel, nitrided crankshafts. All other A-series engines had EN16T steel crankshafts which were only Tuftrided on Mk3 'S' and Austin 1300GT (ADO16) and were stamped 12G1683.

1275cc, Solid wall block (no tappet chest covers)
12G/Ta/H ADO17 shape Wolseley, Riley, MG & Vanden Plas fitted with S rods
12H379 1275GT with dynamo, negative earth, electric fuel pump and remote type
gearbox
12H380 1275GT with alternator, negative earth, electric fuel pump and remote type
gearbox

12H389 1275GT with dynamo, negative earth, mechanical fuel pump and remote type
gearbox
12H390 1275GT with alternator, negative earth, mechanical fuel pump and remote type
gearbox
12H706 1275GT with alternator, negative earth, mechanical fuel pump and rod change
gearbox
12H397 Cooper S Mk3 with dynamo and negative earth
12H398 Cooper S Mk3 with alternator and negative earth
12H/-/ 1275 Austin ADO16 & Allegro
12H610/635 Innocenti Mini with duplex cam drive gears and 11-stud head
12H719/832 Innocenti Mini with simplex cam drive gears and 11-stud head

1275cc, 1990 onwards (12A numbers)
12A/2A Carburrettor type
12A/2B Carburrettor and catalyst type
12A/2D SPi (Single Point injection - Tbi, throttle body injection) with 9.4-1 CR
12A/E SPi (Tbi - throttle body injection) with 10-1 CR
With the following suffixes:
F53 10.0-1CR, 3.105 final drive, catalyst, oil cooler
F75 9.4-1CR, SPi, 3.105 final drive, closed loop catalyst
F76 9.4-1CR, automatic with closed loop catalyst
F77 10.0-1CR, SPi Cooper, 3.2 final drive, closed loop catalyst
G01 10.0-1CR, 3.105 final drive, catalyst, no oil cooler
G03 9.4-1CR, 3.105 final drive, catalyst, May 1992 onwards
G04 9.4CR, 2.76 final drive, catalyst, French only spec
G05 9.4-1CR, automatic with catalyst

Factory replacement engine reference numbers (i.e. New, and Gold and Silver Seal units)
8G28 850cc - Oil feed to primary gear type crank with 1.375-inch tail shaft
8G35 850cc - Deva bush conversion type crankshaft with 1.375-inch tail shaft
8G45 850cc - Gold Seal, 1.5-inch self oiling primary gear/crankshaft type
GSE1101E 850cc - Gold Seal unit
RKM1101E 850cc - Silver Seal unit
BHM1307E 850cc - Gold Seal unit, 85H prefix replacement
8G18 997cc Cooper - Oil feed to primary gear type crankshaft
8G29 997cc Cooper - Deva bush type primary gear and crankshaft
8G36 997cc Cooper - Oil feed converted primary gear and crankshaft
8G33 998cc Cooper - Fitted with 28G193 (12G202) cylinder head
8G40 998cc Cooper - 28G222 (12G295)cylinder head introduced
8G42 998cc Cooper - Closed circuit breathing rocker cover and side plates
8G49 998cc Cooper - Purolator oil filter with oil light switch introduced
GSE1103E 998cc Cooper - Gold Seal unit, was RKM1120E Silver Seal
RKM1103E 998cc Cooper - Silver Seal unit
8G57 998cc - New from 1969 and exchange for all pre-A+ up to 1981
GSE1102E 998cc -Gold Seal unit, was RKM1119E Silver Seal unit, pre-A+ up to 1981
RKM1102E 998cc - Silver Seal unit, pre-A+ up to 1981
RKM1119E 998cc - Silver Seal unit, replaced by RKM1102E, pre-A+ up to 1981
BHM1232 998cc - Low compression dished piston, CAM6267 camshaft, early cylinder head
and crankshaft main bearings with side locator tang, A+
BHM1377 998cc - High compression flat top piston, CAM4717 camshaft, early cylinder head
and crankshaft main bearings with side locator tang, A+
BHM1458 998cc - Low compression piston, CAM6267 camshaft, late A+ cylinder head and
crankshaft main bearings with central locator tang, A+
BHM1460 998cc - High compression press-fit wrist pin piston, CAM4717 camshaft, late A+
cylinder head and crankshaft main bearings with central locator tang, A+
LBB10089 998cc - Low compression press-fit wrist pin piston, CAM6267 camshaft, lead -
free late A+ cylinder head and crankshaft main bearings with central
locator tang, A+
8G156E 1100cc - Clubman, Special and Austin 1100 (ADO16)
RKM1150E 1100cc - Silver Seal unit for Clubman and Special
RKM1151E 1100cc - Silver Seal unit for Clubman and Special
BHM1042 1100cc - New and Gold Seal units for Clubman and Special, 1974-1980
BHM1229 1100cc - New and Gold Seal units for Clubman and Special, A+ Block, 1980 on
8G38 970cc - Gold Seal unit, pre closed circuit breathing, Cooper S
8G41 970cc - Gold Seal unit with closed circuit breathing sideplates, Cooper S
8G46 970cc - Gold Seal unit withoil light switch in filter housing, Cooper S
8G133 1070cc - Gold Seal unit, pre closed circuit breathing, Cooper S
8G153 1070cc - Gold Seal unit with closed circuit breathing side plates, Cooper S
8G145 1275cc - Pre closed circuit breathing unit, Cooper S
8G154 1275cc - Closed circuit breathing side plates unit, Cooper S
8G155 1275cc - Oil filter housing with oil pressure light switch, Cooper S
8G174 1275cc - Fitted with AEG510 camshaft, Cooper S
38G464 1275cc - Introduced in 1970, most of which were fitted with EN16 Tuftrided
crankshaft
8G200 1275cc - New and Gold Seal units Clubman 1275GT
38G527 1275cc - New and Gold Seal units for engine numbers prefixed 12H706, 12H707 &
12H831 for Clubman 1275GT
RKM1130E 1275cc - Silver seal unit, was RKM1112E, for Clubman 1275GT, pre-A+
RKM1152E 1275cc - Silver Seal unit for Clubman 1275GT, pre-A+
RKM1112E 1275cc - Silver Seal unit for Clubman 1275GT, pre-A+
BHM1220 1275cc - A+ unit for Clubman 1275GT
8G199E 1275cc - Gold Seal unit with Duplex cam drive gears for 1300GT (ADO16) and
Innocenti 1300, 11-stud cylinder head
38G559E 1275cc - Gold Seal unit with Simplex cam drive gears for engine numbers prefixed
12H719 and 12H832, for 1300GT (ADO16) and Innocenti 1300, 11-stud
cylinder head
GSE1109E 1275cc - Gold Seal unit for 1300GT (ADO16) and Innocenti 1300, 11-stud cylinder
head
RKM1133E 1275cc - Silver Seal unit for 1300GT (ADO16) and Innocenti 1300, 11-stud
cylinder head
BHM1209E 1275cc - Gold Seal unit, replaced all Innocenti 1300 engines from engine numbers
prefixed 12H610, 12H635 and 12H832

Notes:
All engines pre-fixed with 'GSE' or 'RKM' were of UNIPART origin when BL split its parts organisation.

'E' at the end of a part number denotes it is a reconditioned, service unit only (basic engine assembly with no ancillaries).

'N' at the end of a part number denotes a brand new unit.