Somerford Mini Ltd. Ordering Parts Using This Catalogue

Welcome to Somerford Mini Ltd. 

Somerford Mini Limited was established in 1990 by Peter Hines, a Mini enthusiast. The 

company has been very successful and now boasts a huge spares department alongside 

the original restoration business. Manned by restorers with a deep passion for (and vast 

knowledge and experience of) the Mini, our workshop enjoys a reputation as one of the 

country’s leading Mini restoration centres. With the spares and restoration departments 

together as a team, we have the full blessing of MG Rover, through being a British 

Motor Heritage Approved Specialist. We are justifiably proud of this accolade. 

The spares side of the business started in 1994 and has grown at an incredible rate. 

We now stock over 8000 lines, with more being added all the time. We cater for all 

Minis, from 1959 to the end of production in 2000, with the parts needed to carry out 

a full restoration, including very specialised body fittings that are not otherwise widely 

available. Other stock ranges from service items right the way through to accessories, 

performance parts and all the latest gizmos to dress up your Mini. 

Somerford Mini Limited is still a small enough company to guarantee a personal 

service, a very important consideration. Unlike many of our competitors, we can offer 

proper advice before you make your purchase. We know from our own workshop 

experience what works and what doesn’t, so if you’re not sure about something please 

ask – the chances are we can help. Our workshop is also able to fit any part we sell, 

if you so choose. We take a pride in being totally honest with our customers and not 

making false promises (tales of which you hear only too often with some mail order 

companies). 

We look forward to helping you to care for your cherished Mini. 

Peter Hines 

Somerford Mini Limited. 

Ordering Parts 

When ordering parts, it is very helpful if you also provide us with information 

about your car. Details such as the chassis number (or vehicle identification 

number on later models), engine number, year of manufacture, whether the car is 

right or left hand drive and details of any modifications will all help to ensure you 

get the parts you need. 

You can order parts by telephone, fax, mail, e-mail, through our website, or 

alternatively you would be most welcome to visit our shop during normal trading 

hours (Monday to Friday 9.00am to 6.00pm, Saturday 9.00am to 2.00pm, Sunday 

closed). We provide a range of methods of despatch for your order, from regular 

post through to next day courier delivery. Sometimes the method of despatch is 

dependant on the weight or size of your order. We are of course happy to give 

you a quotation, including delivery costs, before you place your order with us. 

Using This Catalogue 

Illustrations and Illustration Numbers: The illustrations are carefully 

crafted to guide you to the parts you want for your car. Each assembly is depicted 

in an exploded format and for consistency,where practicality permits, the view is from 

a left hand front three quarter angle (we’re also aware that many customers use 

catalogues as a visual guide to the assembly procedure of their car!). If only one hand 

is illustrated of a part with right and left hand versions, both hands will be listed 

under the illustration number in the text, usually with the right hand listed first. 

Part Number: A part number is the identifying name for a part in our stock 

control system, and differentiates between versions – right hand or left hand, early or 

late model. We ask you, where you can,to use part numbers when ordering – it helps 

to guarantee you get the exact parts you need. If you can’t work out which part 

number or you’re having difficulty working out exactly what it is you need, please 

contact us. We are only too happy to guide you or work it out for you. 

Description: We need to clarify here what we mean by right and left hand. 

Right and left hand is always taken from a viewpoint of sitting in the car, not from 

standing in front of it. So why don’t we say ‘offside’ or ‘nearside’? Because offside for 

a right hand drive car is nearside for a left hand drive car (you can see how this 

becomes easily confused…). 

Quantity Required: This is always the quantity required per car. For 

example, if two bolts hold a hinge, and there are four hinges on the car, the quantity 

required will be shown as 8, not 2. 

Remarks: This is additional descriptive information to help you identify the part 

you need, to tell you exactly what you’ll receive if you order that part, or to make you 

aware of an available alternative. It does this by telling you to which models or in 

which years a part was originally fitted (if there is a choice), or what that part 

includes, or whether that part can be used on other models. 

Parts Availability 

While the great majority of the parts listed in this catalogue are currently available, 

there are some that are not. A few of the parts shown in this catalogue are there 

in anticipation of what may become available in future (new or reintroduced products 

are constantly under development). A handful of others are there to historically 

acknowledge what would have originally been fitted and are, where possible, accompanied 

by an alternative, serviceable product. It therefore follows that this catalogue does not 

constitute a definite offer for sale of any particular item. 

In the accompanying price list, a price beside the part number indicates that the part 

is usually available; if the part number is absent it indicates non-availability. If the 

comment ‘use’ (followed by a different part number) is found, the original part has 

been superseded by an available alternative. 

Overseas customers should note that sometimes shipments will be subject to local 

import duties, which are not included in the price we charge for your order, or the 

delivery costs. These duties must be paid by you before you can receive your 

shipment. Value Added Tax at the current United Kingdom rate will be levied on all 

orders despatched to countries within the European Community, but will not be 

levied on orders despatched to the rest of the world. 

We accept payments for orders by cash, personal cheque, bank draft, Sterling 

travellers cheque and most credit or debit cards, including Visa, Mastercard, Maestro 

(Switch) and Delta. If you intend to pay by personal cheque or bankers draft, we 

would advise you to ask for a parts availability check and quotation before placing 

your order. 

Copyright 

Copyright Somerford Mini Limited June 2007 (second edition, December 2008). All 

rights reserved. No part of this publication may be reproduced, stored in a retrieval 

system, or transmitted in any form by any means, electronic, photocopying, recording 

or otherwise without prior written consent of Somerford Mini Limited. 

British Motor Heritage Approval 

Somerford Mini Limited is a British Motor Heritage approved specialist. Our agreement 

with British Motor Heritage permits the use of certain marque logos and some of the 

artwork contained in this catalogue. The remainder of the artwork is the intellectual 

property of Somerford Mini Limited. 

Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk

No. Part No. Description Qty. Remarks No. Part No. Description Qty. Remarks 

Change Points 

In the catalogue you will see parts changes referred to by dates. We have steered 

away from the tradition of listing change points by chassis or commission number 

(they’re different, and the factory parts books used both) because they are so 

complicated on Minis. All the models had different change points until 1984 (after 

which it got much easier) and to list change point numbers often amounts to half a 

page of text! 

As a result, we’ve used years instead. While much more simple, we acknowledge that 

using dates to portray change points is not perfect. For example, you will know the 

year of registration of your car but you might not know the year of manufacture - the 

two aren’t necessarily the same. Also, a revised part was often introduced during a 

year rather than at the beginning or end of it. If you have difficulty in establishing 

which part is for your car, you will find a list of Mini models production history at the 

end of this catalogue which may help. If it doesn’t, contact us, preferably with your 

chassis, commission or engine number to hand, and we’ll do our best to sort it out 

for you. 

The other three Mini engine sizes make up the ‘big bore’ engines and have 

capacities of 970cc, 1071cc and 1275cc. It may seem a misnomer to call the 970cc 

and 1071cc units ‘big bore’ (in light of the largest ‘small bore’ engine being the 

1098cc unit), but in fact it is correct because both have the same large dimension 

cylinder bore as the 1275cc engine; only the engine stroke dimension differs 

between them. The ‘big bore’ engines can, like the ‘small bore’ units, also be split 

into two sub-groups, these being the Cooper S engines of 970cc, 1071cc and 1275cc 

and the distinctly different non-Cooper S engines of 1275cc. Again, this is how you 

will find the ‘big bore’ engines categorised in this catalogue. 

Comprehensive descriptions of each of the seven Mini A Series engines, their 

histories and identification data may be found at the start of each engine section. 

Contact Us 

Somerford Mini Limited 

Unit 2 Broadfield Farm, Great Somerford, Chippenham, 

Wiltshire, SN15 5EL 

The A Series Engine and The Mini 

The British Motor Corporation’s A Series engine family remained in production 

longer, and was built in far, far greater numbers than any other volume-built 

British motor car engine. In the 49 years between the earliest variant, the 803cc 

engine in the Austin A30 of 1951, and the last 1275cc Mini engine in 2000, it is 

estimated that somewhere around 12 million A Series power units were made. 

This comfortably beats the next longest produced engine, the Jaguar XK unit, which 

ran for 43 years but of course only managed to total a tiny fraction of the A 

Series’ production quantity. 

With the Mini being in production for 41 of the A Series engine’s 49 year life and 

taking 5.4 million of the 12 million or so engines produced, it is no surprise to 

find that the Mini has the closest association of any A Series engined car to that 

engine. There were nine different sizes or capacities of A Series built at the BMC/ 

Leyland/Rover Longbridge factory (engine tuners and modifiers have over the years 

added several more), of which only two didn’t make it into one Mini model or 

another on the production line. 

Both the aforementioned 803cc unit (used in the Austin A30 and Morris Minor) and 

the 948cc unit (which saw service in the Austin A35 and A40, Morris Minor, Austin 

Healey Sprite and MG Midget) were only built in ‘in-line’ configuration and were 

thus unsuitable for the Mini, which of course required a specially designed 

transverse, or sideways situated, engine attached to an underslung gearbox. Even 

this statement is not quite true, since a very small number of pre-production 

prototype Minis were in fact fitted for a short while with hand-built 948cc power 

units; none are believed to have survived. 

Of the seven engine sizes which were fitted during Mini production, four were what 

have come to be known as ‘small bore’ engines: the 848cc, 997cc, 998cc and 

1098cc units. These four can be comfortably split into two sub-groups. The 848cc 

and 997cc engines are very closely related and share many components, the latter 

being a direct, larger capacity development of the former (the first Mini engine) for 

fitment in the earliest Mini Coopers. The 998cc and 1098cc engines form the 

other sub-group, although in this case the smaller capacity 998cc engine - destined 

to become the most commonly found engine under a Mini bonnet - was developed 

from and shares many parts with the 1098cc unit, which was first used in the 

Austin/Morris 1100 of 1962 and which wasn’t itself fitted to British-built Minis until 

1975. This is why, as you read through this catalogue, you will find 848cc/997cc 

parts and 998cc/1098cc parts grouped together in their own sections. 

e-mail spares@somerford-mini.co.uk 

Tel. 01249 721421 Fax. 01249 721316 

Opening Times 

Monday to Friday: 9.00am to 6.00pm 

Saturday: 9.00am to 2.00pm Sunday: Closed 

Contents 

External Engine - 848 and 997cc 2 

External Engine - 998 and 1098cc 6 

External Engine - 1275cc (not Cooper S) 10 

External Engine - 970, 1071 and 1275cc (Cooper S) 14 

Internal Engine - 848 and 997cc 18 

Internal Engine - 998 and 1098cc 22 

Internal Engine - 1275cc (not Cooper S) 26 

Internal Engine - 970, 1071 and 1275cc (Cooper S) 30 

Cylinder Head - 848 and 997cc 34 

Cylinder Head - 998 and 1098cc 38 

Cylinder Head - 1275cc (not Cooper S) 42 

Cylinder Head - 970, 1071 and 1275cc (Cooper S) 46 

Oil Pumps and Oil Pressure Relief Valve 50 

Oil Filters and Oil Pipes 52 

Engine Mountings 56 

Brief Mini Production History 60 

Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk 1

External Engine - 848 and 997cc 

© Copyright Somerford Mini Limited 

2 




848 and 997cc Engine Identification 

The 848cc A Series engine was the original engine in the Mini when the car was launched in 1959. It 

continued in production until the cessation of the Mini Van, the last batches of which made it to 

commercial fleet operators in early 1984. Like other Mini engines that continued in production after the 

1970s, the 848cc engine received a timing chain tensioner pad at the end of that decade. 

However it never got the strengthened cylinder block or the other ‘A Plus’ modifications wrought on the 

998, 1098 and 1275cc engines - the 998 (which shared its block with the 1098) and 1275cc engines 

being scheduled to have much longer production lives in the Austin Metro.1980s 848cc engines can 

therefore only be easily identified by a bulge in the timing chain cover, giving away the fact that there 

is a chain tensioner pad assembly inside. 848cc engines used with automatic gearboxes are different in 

several respects to those used with manual; 848cc automatics ceased production in 1971. 

In fact, the only other BMC/Leyland vehicles to use the 848cc engine were the Mini Moke, a handful of 

early 1980s Metro Vans and the final batch of Austin A35 Vans built as AA patrol vans in 1968! The 

latter was the only non-transverse 848cc A Series engine type ever produced, incidentally, while it would 

be very unlikely indeed for you to find one of the other two transplanted into your Mini. 

The 997cc A Series engine is most closely related to the 848cc unit from which it was directly developed 

(which is why it is included with the 848cc engine in sections of this catalogue). It only saw use in one 

model of Mini, the first incarnation of Mini Cooper, and was produced from 1961 to 1963. The only 

other application of note for a 997cc A Series was in John Cooper’s ‘Formula Junior’ racing cars, from 

which most of the components were borrowed for the Mini Cooper. 

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 848 and 997cc 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 always relates to the compression ratio of the engine: H for high compression, L for low 

compression. 

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 w ere not necessarily the same design, all lumped to gether. In other words, parts used 

in the rebuild were frequently incorrect in an historic sense for the engine being rebuilt. 

848 and 997cc Engine Serial Number Prefix Codes 1959-69 

8A/ 848cc Austin manual gearbox engines only up to engine no. 25000 (1959-60) 

8MB/ 848cc Morris manual gearbox engines only up to engine no. 25000 (1959-60) 

8AM/ 848cc Austin and Morris manual gearbox engines without closed circuit breathing from 

engine no. 25001 (1960-69) 

8AH/ 848cc Austin and Morris automatic gearbox engines without closed circuit breathing 

(1964-69) 

8AJ/ 848cc Austin and Morris manual gearbox engines with closed circuit breathing (1964-69) 

8AK/ 848cc Austin and Morris automatic gearbox engines with closed circuit breathing (1964-69) 

8WR/ 848cc Wolseley and Riley manual gearbox engines (1961-63) 

9F/SA 997cc Austin and Morris Cooper manual gearbox engines (1961-63) 

848cc Engine Serial Number Prefix Codes 1969-84 

85H/ Engines from 1969 onwards 

With the advent of 85H/ serial numbers in 1969, the codes became far more complex. 85H/ was 

followed by a three digit number and either one or two letters . The number referred to the 

transmission fitted (manual/automatic, type of gearchange, type of drive shaft joints, final drive ratio etc .), 

the charging system fitted (dynamo or alternator), plus any unusual specifications (Police, Post Office or 

other utility users, export market specific requirements). 

The one or two letters following the three digit number referred to emission controls fitted (type of 

crankcase ventilation, air intake system, evaporative loss control, etc .). Unfortunately with regard to the 

848cc engine there are too many combinations of 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. 

BMC/Leyland/Unipart Mini 848 and 997cc Reconditioned Engine P art Nos. 

8G13 848cc manual gearbox engine, with 1 3/8" tail diameter type crankshaft accepting oil-fed 

primary gear bush (1959-62; replaces D.U. bush type) 

8G28 848cc manual gearbox engine, with 1 3/8" tail diameter type crankshaft for Deva primary 

gear bush (1962-63) 


gear bush and warning light type oil filter head (1964-67) 


gear bush and non-warning light type oil filter head (1964-80) 

GSE1101 848cc manual gearbox engine; later ‘Gold Seal’ part number. Spec. as 8G45 (1964-80) 

RKM1101 848cc manual gearbox engine; later ‘Silver Seal’ part number. Spec . as 8G45 (1964-80) 

RKM1118 848cc manual gearbox engine; later ‘Silver Seal’ par t number. Spec. as 8G45; replaced 

RKM1101 (1964-80) 

BHM1307 848cc manual gearbox engine, with 1 1/2" tail diameter type crankshaft for Deva primary 

gear bush and timing chain tensioner (1980-84) 

8G52 848cc automatic gearbox engine without closed circuit breathing (1964-69) 

8G53 848cc automatic gearbox engine with closed circuit breathing (1964-71;848cc automatic 

discontinued after 1971) 

8G18 997cc high compression engine, with 1 3/8" tail diameter type crankshaft accepting oil-fed 


8G36 997cc high compression engine, with 1 3/8" tail diameter type crankshaft for Deva primar y 


8G29 997cc high compression engine, with 1 1/2" tail diameter type crankshaft for Deva primar y 

gear bush (1963) 

8G23 997cc low compression engine , with 1 3/8" tail diameter type crankshaft accepting oil-fed 


8G37 997cc low compression engine, with 1 3/8" tail diameter type crankshaft for Deva primary 


8G30 997cc low compression engine, with 1 1/2" tail diameter type crankshaft for Deva primary 

gear bush (1963) 

There never was a differentiation made between open circuit or closed circuit breathing, nor between 

dynamo or alternator fitment, on manual transmission reconditioned engines. The factory instructed that 

the parts concerned (rock er cover, tappet cover, pulley etc.) should be swapped over from the old engine 

to the new one as required. All factory reconditioned 848cc engines were high compression ratio units . 

Rebuilt or Repaired Engine Assemblies 

Somerford Mini Ltd. offers an engine rebuilding and repair service, courtesy of its workshop facility. We 

can carry out repairs or rebuilds on late-model engines, but the extent of rebuilding on an early engine is 

governed by - and sometimes restricted by - par ts availability. 

Please contact us to discuss your Mini engine requirements - it would be helpful if you could supply us 

not only the details of what’s gone wrong with your engine , but also the full engine number (if known) 

and type (capacity, high or low compression, gearbox, breathing system, etc.). The more you can provide 

us with,the better we can ascertain how we might possibly help you. 

Gasket Sets 

1 GUG49 GASKET SET, con version (‘bottom end set’)1 Manual gearbox models. 

GEG254 GASKET SET, con version (‘bottom end set’)1 Automatic gearbox models. 

Conversion gasket sets (often called ‘bottom end’ or ‘supplementary’ sets) include gaskets for the following: 

water pump, front cover, tappet chest covers, front mounting plate, oil pump, oil filter head, engine to 

gearbox joint and flywheel/torque converter housing. Washers, seals and O rings are included for the 

following: priming plug, drain tap/plug, main bearing cap, front cover, tappet chest covers, distributor 

housing and oil suction pipe. Note that the tappet chest cover gaskets included are the post-1966 rubber 

type - customers requiring the earlier cork gaskets should purchase them separately. 

EGS001 GASKET SET, full engine 1 Manual gearbox models. 

The full engine gasket set includes the conversion gasket set listed above plus a cylinder head gask et set 

(‘decoke’ or ‘decarbonising’ set) minus the head gasket itself, which should be purchased separately 

according to the engine size. 

External Engine Components 

2 2K8169 PLUG, core, cylinder block 4 

3 2K1345 PLUG, oil pressure release valve passage 2 

4 12H1734 PLUG, oil gallery 2 

5 ADP210 PLUG, oil feed 1 Automatic gearbox. 

6 1B3664 WASHER, sealing 1 Automatic gearbox. 

7 1A1964 RESTRICTOR, cam bearing oil feed 1 

8 CAM150 STUD, cylinder head, long 4 

9 CAM151 STUD, cylinder head, short 5 

10 CHS2513 STUD, fuel pump drive aperture 2 1959-69. 

CHS2515 STUD, fuel pump drive aperture 2 1969 on. 

From 1959-69 the fuel pump drive aperture studs secured a blanking plate, plus the open circuit 

breathing vent pipe (if fitted). From 1969 onwards, they secured the mechanical fuel pump. For 

mechanical fuel pump fixing details, including the gasket (which is not the same as the blanking plate 

gasket), please see the ‘Fuel Pumps - Carburetter’ section in the Fuel and Exhaust Systems area of the 

Somerford Mini Catalogue. 

Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk 

3



4 




External Engine Components (continued) 

11 2A265 PLATE, blanking fuel pump drive aperture 1 1959-69. 

12 GUG705557GM GASKET, blanking plate 1 1959-69. 

13 FNZ105 NUT, blanking plate to block 2 1959-69. 

14 LWZ205 WASHER, locking 2 1959-69. 

15 PWZ105 WASHER, plain 1 Required for open circuit breathing 

vent pipe bracket (if fitted). 

16 53K615 STUD, oil filter head 2 Manual gearbox, 1959-73. For paper 

element oil filters. 

CHS2613 STUD, oil filter head 2 Manual gearbox, 1973 on. For ‘spin 

on’ cartridge oil filters. 

The first automatic gearbox Minis of 1964-65 had an adaptor and pipe running from what would have 

been the oil filter head mounting face on a manual engine down to the gearbox. From mid-1965 this 

was dispensed with in favour of an oil pipe more similar in design to that used on a manual power unit, 

leaving all subsequent automatic-type engines wearing a blanking plate where the adaptor had been 

fitted. Full details of the adaptor and oil pipes may be found in the Oil Filters and Oil Pipes section of 

the Somerford Mini Catalogue. 

17 22A1203 PLATE, blanking cylinder block oil filter 1 Automatic gearbox, 1965-71. 

face 

18 88G402 GASKET, blanking plate 1 Automatic gearbox, 1965-71. 

19 SH506071 SCREW, blanking plate to block 2 Automatic gearbox, 1965-71. 

20 12G1058 WASHER, sealing 2 Automatic gearbox, 1965-71. 

21 12A1910 SCREW, main bearing cap to block 6 

22 2A54 DOWEL,main bearing cap 6 

23 6K927 LOCK TAB, main bearing cap screw 6 

24 2A52 LINER, camshaft bearing 1 848cc . 

25 BHM1211 LINER SET, camshaft bearings 1 997cc . 

26 3H576 TAP, cooling system drain 1 Alternative to plug. 

27 2K4954B WASHER, fibre, drain tap A/R 

This washer not only seals the tap to the block, but also is intended (using whatever quantity is 

necessary) to shim the tap so that when tightly screwed to the block the spout faces downwards. 

28 53K2853 PLUG, cooling system drain 1 Alternative to tap. 

29 6K638B WASHER, sealing plug 1 

30 2A612 HOUSING, distributor 1 1963-65; does not require O ring. 

31 12A1136 HOUSING, distributor 1 1965 on; requires O ring. 

32 13H2792 O RING, housing 1 1965 on. 

The later 12A1136 distributor housing may be fitted in place of the earlier 2A612 housing, but only if a 

13H2792 O ring is fitted with it. 

33 SH604061 SCREW, housing to block 2 

34 LWZ404 WASHER, shakeproof 2 

Engine Front Mounting Plate 

35 2A970 PLATE, engine front mounting 1 1959-79. 

36 12G2626 PLATE, engine front mounting 1 1979 on. Accepts chain tensioner. 

37 GUG705554GM GASKET, plate to block 1 

38 SH605051 SCREW, plate to block 2 

39 LWZ305 WASHER, locking 2 

40 53K2016 SCREW, plate to main bearing cap 2 

41 6K831 LOCK TAB, screw 1 1959-69. 

42 WF600041 WASHER, shakeproof 2 1969 on. Will replace lock tab on 

earlier engines. 

43 AHU2379 PLATE, camshaft locating 1 


45 WF600040 WASHER, shakeproof 3 

Timing Cover 1959-79 (without chain tensioner pad) 

Several timing covers were fitted in the 1960s , some with timing pointers, some without and most with 

stiffeners, one without. All were superseded by 1970 by 12G2506, which includes a timing pointer and 

integral lo wer stiffener and does not therefore require the stiffener 12A666 listed below. The plain 

washers PWZ104 and PWZ105 listed here replace the original elongated washers used at different times 

on the A Series engine until the 1980s . 

46 12G2506 COVER, front, timing 1 Includes oil seal. 

47 88G561 OIL SEAL, timing cover 1 Included in timing cover. 

48 12A666 STIFFENER, timing cover 1 Use on ear ly 1960s covers suffering 

from poor sealing. 

49 12A956 GASKET, timing cover 1 

50 SH604031 SCREW, timing cover to front mounting 6 

plate 


52 PWZ104 WASHER, plain 6/3 Qty. reduced if stiffener is present. 

53 SH605061 SCREW, timing cover to mounting plate 4 

and block 


55 PWZ105 WASHER, plain 4/3 Qty. reduced if stiffener is present. 

Timing Cover 1979 On (with chain tensioner pad) 

56 CAM4641 COVER, front, timing, accepts chain 1 1979-80; includes oil seal. 

tensioner pad 

CAM4904 COVER, front, timing, accepts chain 1 1980 on; includes oil seal. 

tensioner pad 

A Plus type. 


58 GUG705550GM GASKET, timing cover 1 1979 on; for CAM4641 and CAM4904 

covers. 


plate 


61 PWZ104 WASHER, plain 6 

62 SH605061 SCREW, timing cover to mounting plate 5 

and block 



65 FNZ105 NUT,timing cover to mounting plate 1 

Tappet Chest Covers 

66 - COVER, tappet chest,LH, with breather 1 Convex cover; for open circuit 

pipe breathing (1959-66). 

67 - COVER, tappet chest,LH, with breather 1 Concave cover ; for open circuit 

pipe breathing (1966-69). 

68 12G577 COVER, tappet chest,LH, with oil 1 Convex cover; for closed circuit 

separator breathing (1964-66). 

69 12A1212 COVER, tappet chest,LH, with oil 1 Concave cover; for closed circuit 

separator 

breathing (1966 on). 

There are too many varieties of LH tappet chest cover for open circuit engine breathing models to list 

here. However they are all detailed, along with all of the other components of each type of breathing 

system,in the ‘Emission Controls - Engine Breathing’ sections in the Fuel and Exhaust Systems area of the 

Somerford Mini catalogue. 

70 12H941 COVER, tappet chest,RH 1 Convex cover, 1959-66. 

71 12A1386 COVER, tappet chest,RH 1 Concave cover, 1966 on. 

72 12A1139 GASKET, cover, cork 1 For convex type cover. 

73 BH605151 BOLT, cover to block 1 For convex type cover. 

74 2K4458 WASHER, bolt 1 For convex type cover. 

75 GUG705505GM GASKET, cover, rubber 1 For concave type cover. 

76 SH605091 SCREW, cover to block 1 For concave type cover. 

77 12A1177 WASHER, cup 1 For concave type cover. 

78 12A1176 BUSH, r ubber 1 For concave type cover. 

79 MRC1980A BUSH, r ubber 1 Later design; replaces 12A1176 and 

12A1177. 

Oil System Components 

80 2K4994 PLUG, priming 1 

81 6K464 WASHER, sealing 1 

82 12H865 PLUNGER, oil pressure relief valve 1 Standard fitment. 

83 BLS916 BALL, oil pressure relief valve 1 Alternative; see note below. 

The transverse A Series engine is quite susceptible to a sticking oil pressure relief valve because its 

lubricating oil is shared with the gearbox and dirty oil ends up carrying fine metallic particles from the 

gearbox into the engine (Never skimp on Mini oil changes!). Almost invariably, if the valve is going to 

stick it will do so in the wide open position when the oil is cold and thick. As the oil warms it gets 

thinner; because the valve is still stuck wide open the oil pressure drops alarmingly - the oil pump can’t 

keep up with thin oil and a wide open valve - and the engine ceases to be lubricated correctly. 

The BLS916 ball listed above may be used in place of the standard fitment plunger to guard against a 

sticking relief valve. It must, however, be used in conjunction with the shorter and stronger AEA536 relief 

valve spring. 

84 6K853 SPRING, oil pressure relief valve 1 848cc . 

AEA536 SPRING, oil pressure relief valve 1 997cc . 

85 12A1851 CAP, threaded, relief valve 1 


87 2A797 HOUSING, oil pressure relief valve 1 Press-fit in cylinder block. 

88 12A116 DIPSTICK, oil level 1 Manual gearbox; 848 and 997cc. 

89 AEC671 WASHER, sealing dipstick 1 Manual gearbox; 848 and 997cc. 

90 12G107 TUBE, dipstick, plastic 1 Manual gearbox; 997cc. 

For the dipstick on Minis with automatic gearboxes, please see the ‘Automatic Transmission - Torque 

Converter and Housing’ section in the Transmissions area of the Somerford Mini catalogue. 


5



6 




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) 


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. 







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 


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 


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. 


7



8 






can carry out repairs or rebuilds on late-model engines, but the extent of rebuilding on an early engine 

is governed by - and sometimes restricted by - parts availability. Please contact us to discuss your Mini 

engine requirements - it would be helpful if you could supply us not only the details of what’s gone 

wrong with your engine, but also the full engine number (if known) and type (capacity, high or low 

compression, gearbox, breathing system, etc.). The more you can provide us with, the better we can 

ascertain how we might possibly help you. 

Gasket Sets 

1 GUG49 GASKET SET, conversion (‘bottom end set’)1 Manual gearbox models. 

GEG254 GASKET SET, conversion (‘bottom end set’)1 1967-79, automatic gearbo x models. 

LVQ10035 GASKET SET, conversion (‘bottom end set’) 1 1979 on, automatic gearbox models. 


water pump, front cover, tappet chest covers, front mounting plate, oil pump, oil filter head, engine to 

gearbox joint and flywheel/torque converter housing. Washers, seals and O rings are included for the 

following: priming plug,drain tap/plug, main bearing cap, front cover, tappet chest covers, distributor 

housing and oil suction pipe. Note that the tappet chest cover gaskets included are the post-1966 

rubber type - customers requiring the earlier cork gaskets should purchase them separately. 

EGS001 GASKET SET, full engine 1 Manual gearbox models. 

The full engine gasket set includes the conversion and cylinder head gasket sets minus the head gasket 

itself, which should be purchased separately according to the engine size. 


2 2K8169 PLUG, core, cylinder block, 1 5/8" dia. 4 1963-80. 

AEC876 PLUG, core, cylinder block, 1 3/8" dia. 4 1980 on (A Plus block). 

3 2K1345 PLUG, oil pressure release valve passage 2 1963-85. 

TAM2009 PLUG, oil pressure release valve passage 2 1985 on. 

4 12H1734 PLUG, oil gallery, solid brass 2 1963-85, 998cc. 

CAM4133 PLUG, oil gallery, cup type 2 1985 on, 998cc. 

12G3503 PLUG, oil gallery 2 1098cc . 

5 ADP210 PLUG, oil feed 1 Automatic gearbo x. 

6 1B3664 WASHER, sealing 1 Automatic gearbo x. 



9 CAM151 STUD, cylinder head, shor t 5 

10 CHS2513 STUD, fuel pump drive aperture 2 1963-69. 

CHS2515 STUD, fuel pump drive aperture 2 1969 on. 

From 1963-69 the fuel pump drive aperture studs secured a blanking plate, plus the open circuit 

breathing vent pipe (if fitted). From 1969 onwards, they secured the mechanical fuel pump. For pump 

fixing details, including the gask et (not the same as the blanking plate gasket), please see the ‘Fuel 

Pumps - Carburetter’ section in the Fuel and Exhaust Systems area of the Somerford Mini Catalogue. 

11 2A265 PLATE, blanking fuel pump drive aperture 1 1963-69. 

12 GUG705557GM GASKET, blanking plate 1 1963-69. 

13 FNZ105 NUT, blanking plate to block 2 1963-69. 


15 PWZ105 WASHER, plain, vent pipe bracket 1 Open circuit breathing (if fitted). 

16 53K615 STUD, paper element oil filter head 2 Manual gearbox, 1963-73. 

CHS2613 STUD, ‘spin-on’ cartridge oil filter head 2 Manual gearbox, 1973 on. 

17 22A1203 PLATE, blanking oil filter face 1 Automatic gearbo x. 

18 88G402 GASKET, blanking plate 1 Automatic gearbo x. 

19 SH506071 SCREW, blanking plate to block 2 Automatic gearbo x. 

20 12G1058 WASHER, sealing 2 Automatic gearbo x. 

21 12A1910 SCREW, main bearing cap to block 6 

22 2A54 DOWEL,main bearing cap 6 

23 6K927 LOCK TAB, main bearing cap screw 6 

24 BHM1211 LINER SET, camshaft bearings 1 

25 3H576 TAP, cooling system drain 1 Alternative to plug until early 1980s . 

26 2K4954B WASHER, fibre, drain tap A/R 



27 53K2853 PLUG, cooling system drain 1 Alternative to tap. 

28 6K638B WASHER, sealing plug 1 




The later housing may be fitted in place of the earlier item, but only if an O ring is fitted with it. 

32 SH604061 SCREW, housing to block 2 1963-80; not A Plus cylinder block. 

33 LWZ404 WASHER, shakeproof 2 1963-80; not A Plus cylinder block. 


34 2A970 PLATE, engine front mounting 1 1963-79. 

35 12G2626 PLATE, engine front mounting 1 1979 on. Accepts chain tensioner. 




39 53K2016 SCREW, plate to main bearing cap 2 

40 6K831 LOCK TAB, screw 1 1963-69. 

41 WF600041 WASHER, shakeproof 2 1969 on. Will replace earlier lock tab. 




Timing Cover 1963-79 (without chain tensioner pad) 

Several timing covers were fitted in the 1960s; all w ere superseded by 1970 by 12G2506, which does not 

require the stiffener 12A666 listed below. The plain washers PWZ104 and PWZ105 listed below replace 

the original elongated washers used at different times on the A Series engine until the 1980s. 



47 12A666 STIFFENER, timing cover 1 Use on certain early 1960s covers. 


49 SH604031 SCREW, cover to front mounting plate 6 


51 PWZ104 WASHER, plain 6/3 Qty. reduced when stiffener is present. 

52 SH605061 SCREW, cover to mounting plate and block 4 


54 PWZ105 WASHER, plain 4/3 Qty. reduced when stiffener is present. 

Timing Cover 1979 On (with chain tensioner pad) 

55 CAM4641 COVER, front, timing 1 1979-80; includes oil seal. 

CAM4904 COVER, front, timing 1 1980 on; includes oil seal. A Plus. 


57 GUG705550GM GASKET, timing cover 1 

58 SH604031 SCREW, cover to front mounting plate 6 








65 - COVER, tappet chest, LH, with breather pipe 1 Convex; open circuit breathing (1963-66). 

66 - COVER, tappet chest, LH, with breather pipe 1 Concave;open circuit breathing (1966-69). 

67 12G577 COVER, tappet chest, LH, with oil separator 1 Convex;closed circuit breathing (1964-66). 

68 12A1212 COVER, tappet chest, LH, with oil separator 1 Concave;closed circuit breathing (1966 on). 

There are too many varieties of open circuit breathing LH tappet chest cover to list here. However they 

are all detailed, with the other components of each type of breathing system, in the ‘Emission Controls - 

Engine Breathing’ sections in the Fuel and Exhaust Systems area of the Somerford Mini catalogue. 








76 12A1177 WASHER, cup 1 For conca ve type cover; 1963-85. 

77 12A1176 BUSH, r ubber 1 For conca ve type cover; 1963-85. 

78 MRC1980A BUSH, r ubber 1 For concave type cover; 1985 on. 

The MRC1980A bush may be fitted in place of the washer and bush on pre-1985 engines. 






The ball may be used in place of the plunger to prevent a sticking relief valve (which happens with dirty 

oil sometimes). It must,however, be used together with the shorter and stronger AEA536 spring. 

83 6K853 SPRING, oil pressure relief valve 1 Not 998cc Cooper. 

AEA536 SPRING, oil pressure relief valve 1 998cc Cooper. 




87 12A116 DIPSTICK, oil level 1 1963-66; manual gearbox. 

12A1263 DIPSTICK, oil level 1 1966 on; manual gearbox. 

88 AEC671 WASHER, sealing dipstick 1 1963-66; manual gearbox. 

12A1262 WASHER, sealing dipstick 1 1966 on; manual gearbox. 

89 12G107 TUBE, dipstick, nylon 1 1963-66; manual gearbox. 

12A1261 TUBE, dipstick, metal 1 1966-80; manual gearbox. Not A Plus 

engines (see note below). 

Note that ‘hybrid’ engines (with A Plus cylinder block, but not all other A Plus features) produced in the 

1979-81 period also did not require a dipstick tube. For the dipstick on Minis with automatic gearboxes, 

please see the ‘Automatic Transmission - Torque Converter and Housing’ section in the Transmissions area 

of the Somerford Mini catalogue. 


9

External Engine - 1275cc (not Cooper S) 


10 




1275cc Engine Identification 

The first application of the 1275cc A Series engine in the Mini was in 1964, with the advent of the 

1275 Mini Cooper S. This particular engine was however a very different animal to the 1275cc engine 

described on this page; for the Cooper S unit, please refer to the ‘External Engine - 970, 1071 and 

1275cc (Cooper S)’ section of the Somerford Mini catalogue. 

The engine described here made do without the eleven stud cylinder head and many other Cooper S 

engine attributes and did not have tappet chest covers on the bulkhead side of the engine block - for 

this reason it is often referred to as the ‘solid wall block’ 1275cc engine. Its first and only use in a 

Mini for just over ten years was in the 1275 GT model, introduced in 1969 and phased out in 1980. 

During this period the engine was subject to a number of modifications, not least of which were the 

change from twin or ‘duplex’ to single or ‘simplex’ timing chain in 1974 and the gradual introduction of 

‘A Plus’ features at the end of the 1970s. 

Although not programmed for fitment in a Mini bodyshell through the 1980s, the 1275cc engine was 

destined for considerable use in the Austin Metro; for this reason most A Plus modifications were present 

by the time of the 1275 GT’s demise, including the characteristically ribbed (much stronger) cylinder 

block with its completely revised distributor mounting. 

1275cc Mini Engine Serial Number Prefix Codes (not Cooper S) 1969-80 

12H/389 1275 GT manual gearbox engine with remote gearchange, rubber coupling drive shafts and 

dynamo (1969-73). 

12H/390 1275 GT manual gearbox engine with remote gearchange, rubber coupling drive shafts and 

alternator (1969-73). 

12H/706 1275 GT manual gearbox engine with rod gearchange, ‘pot’ joint drive shafts and alternator 

(1973-80). A Plus cylinder blocks ran from engine number 12H/706/-/026400 onwards . 

12H/831 1275 GT manual gearbox engine, as per 12H/706 but Police specification (1974-80). 

1275cc Mini A Plus High Compression Ra tio (10:1) 

Engine Serial Number Prefix Codes 1990-96 

12H/-/F53 Manual gearbox engine for carburetter, with 3.105:1 final drive and oil cooler (1990-91). 

12H/-/G01 Manual gearbox engine for carburetter, with 3.105:1 final drive; without oil cooler (1990-91). 

12H/-/F77 Manual gearbox engine for SPi, 3.21:1 final drive (1991-93). 

12H/-/J02 Manual gearbox engine for SPi, 3.21:1 final drive (1994-96). 

12H/-/J66 Manual gearbox engine for SPi, 3.21:1 final drive , 55 amp uprated alternator (1996). 

12H/-/J77 Manual gearbox engine for SPi, 3.21:1 final drive , 55 amp alternator, air cond. (Japan, 1995-96). 

12H/-/J18 Manual gearbox replacement engine with cylinder head, for SPi (1991-96). 

12H/-/J13 Manual gearbox replacement engine without cylinder head, for SPi (1991-96). 

For the next ten years the Mini soldiered on without a 1275cc variant and the factory declined to put a 

genuine performance Mini in the showroom line up (customers being encouraged to look at the MG 

Metro instead), despite the popularity of 998cc Mini limited editions like Flame and Racing with their 

obvious Mini Cooper styling cues. Finally in 1990 came the new Mini Cooper, complete with a fullyfledged 

A Plus 1275cc engine (borro wed ironically from the MG Metro). 

This was however a ver y different (lead-free fuelled, with catalytic converter) po wer unit to that seen in 

the 1275 GT ten years earlier,having been emasculated to a degree by emission control regulations . 

The process of loading up the engine with more and more regulations-compliant equipment continued 

through the 1990s, the major milestones being the phased replacement of the carburetter by single point 

injection (SPi) from 1991 and a significant overhaul of the power unit design coinciding with the 

introduction of multi point injection (MPi) model in 1997. The 1997 on engine, in both MPi and Japanonly 

SPi guises, is immediately recognisable by the lack of a distributor, or any facility to attach one! 

Meanwhile, by 1992, 1275cc had become the only engine capacity available in the Mini line up (the 

lower-powered 998cc unit could no longer cope with all the extra equipment) and that was the way 

things stayed until the end of Mini production in 2000. Amongst other things this meant that to 

continue to be able to offer an automatic gearbox option, an automatic type 1275cc engine was 

produced for the Mini from 1992. 

Other applications of the transverse 1275cc A Series included the BMC 1100/1300, commonly referred to 

as the ‘ADO16’ range. Higher performance engines from such models as the MG 1300 and Austin/Morris 

1300 GT in the ADO16 range were frequently to be found transplanted into Minis by enthusiasts; 

particularly in favour was the 11 stud head engine, which is not the same as a Cooper S unit, by the 

way. Several other Leyland and Austin Rover cars also used the 1275cc engine, including the Allegro, 

overseas-built Mokes and the Maestro/Montego models (the latter featuring a different transmission which 

rendered Mini transplants impossible). 

The 1980s Metro’s 1275cc unit proved to be the most popular with Mini owners who desired an easy 

performance upgrade, the whole engine/transmission assembly less manifolds fitting comfortably in a Mini 

with very few necessar y modifications. For this reason, if you see an engine from another car under the 

bonnet of a Mini nowadays, it is most lik ely to be one from an MG Metro or its short-lived predecessor, 

the Austin Metro 1.3 S. 


establishing which replacement parts to fit to it. The 1275cc engine number prefixes used on non- 

Cooper S 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 always relates to the 

compression ratio of the engine: H for high compression, L for low compression. A Plus high or standard 

(as ‘low’ was then known) compression engines are by contrast identified by the letter plus two numbers 

part of the engine serial number prefix; a full list of these is shown below. 









1275cc Mini A Plus Standard Compression Ratio (9.4:1) 


Note that while standard compression ratio engines were generally non-Cooper units , some expor t markets 

did receive Coopers with standard compression ratio engines. Moreover, some numbers of Coopers with 

automatic gearboxes were built for export, too. This explains the 1992 start date for standard 

compression ratio SPi manual and automatic engines; these engines only started to be seen in UK (and 

most European markets) cars from 1994. 

12H/-/G03 Manual gearbox engine for carburetter, with 3.105:1 final drive (1992-93). 

12H/-/J04 Manual gearbox engine for carburetter, with 3.105:1 final drive (1993-94). 

12H/-/G04 Manual gearbox engine for carburetter, with 2.76:1 final drive (France, 1992-93). 

12H/-/J05 Manual gearbox engine for carburetter, with 2.76:1 final drive (France, 1993-94). 

12H/-/F75 Manual gearbox engine for SPi, with 3.105:1 final drive (1992-93). 

12H/-/J01 Manual gearbox engine for SPi, with 3.21:1 final drive (1994-96). 

12H/-/J21 Manual gearbox replacement engine with cylinder head, for carburetter (1992-94). 

12H/-/J19 Manual gearbox replacement engine with cylinder head, for SPi (1992-96). 

12H/-/J14 Manual gearbox replacement engine without cylinder head, for carburetter or SPi (1992-96). 

12H/-/G05 Automatic gearbox engine with carburetter (1992-93). 

12H/-/J06 Automatic gearbox engine with carburetter (1993-94). 

12H/-/F76 Automatic gearbox engine with SPi (1992-94). 

12H/-/J03 Automatic gearbox engine with SPi (1994-96). 

12H/-/J92 Automatic gearbox engine with SPi and 2.76:1 final drive ( France , 1994-96). 

12H/-/J20 Automatic gearbox replacement engine with cylinder head, for SPi (1992-96). 

12H/-/J15 Automatic gearbox replacement engine without cylinder head, for carburetter or SPi (1992-96). 

1275cc Mini A Plus High Compression Ra tio (10:1) 


12H/-/K70 Manual gearbox engine for MPi, with 2.76:1 final drive (1997-2000). 

12H/-/K71 Manual gearbox engine for SPi, with 3.21:1 final drive and air conditioning (Japan, 1997-1999). 

12H/-/L13 Manual gearbox replacement engine with cylinder head, for MPi (1997-2000). 

12H/-/L16 Manual gearbox replacement engine with cylinder head, for SPi (Japan, 1997-1999). 

12H/-/L21 Manual gearbox replacement engine without cylinder head, for MPi or SPi (1997-2000). 

1275cc Mini A Plus Standard Compression Ratio (9.4:1) 


12H/-/K72 Automatic gearbox engine for SPi, with air conditioning (Japan, 1997-1999). 

12H/-/L14 Automatic gearbox replacement engine with cylinder head, SPi, air cond. (Japan, 1997-1999). 

12H/-/L15 Automatic gearbox replacement engine without cylinder head, SPi, air cond. (Japan,1997-1999). 

Leyland/Unipart/Rover Mini 1275cc (not Cooper S) 


8G200 Manual gearbox engine, twin ‘duplex’ timing chain (1969-74). 

38G527 Manual gearbox engine , single ‘simplex’ timing chain with tensioner (1974-79). 

BHM1220 Manual gearbox engine, single ‘simplex’ timing chain tensioner, A Plus block (1980). 

RKM1112 Manual gearbox engine; ‘Silver Seal’ par t number. Specification as 8G200 (1969-74). 

RKM1130 Manual gearbox engine; later ‘Silver Seal’ par t number. Replaced RKM1112 (1969-74). 

RKM1152 Manual gearbox engine; ‘Silver Seal’ par t number. Spec . as 38G527 or BHM1220 (1974-80). 

LBB10399 Manual gearbox engine, A Plus, high compression, carburetter (1990-91). 

LBB10476 Manual gearbox engine, A Plus, high compression, SPi (1991-96). 

LBB10479 Manual gearbox engine, A Plus, standard compression, carburetter (1992-94). 

LBB10477 Manual gearbox engine, A Plus, standard compression, SPi (1992-96). 

LBB10480 Automatic gearbox engine, A Plus, standard compression, carburetter (1992-94). 

LBB10478 Automatic gearbox engine, A Plus, standard compression, SPi (1992-96). 

LBB109070 Manual gearbox engine , A Plus, high compression, MPi (1997-2000). 

LBB109080 Manual gearbox engine , A Plus, high compression, SPi (1997-2000). 

LBB109090 Automatic gearbox engine, A Plus, standard compression, SPi (1997-1999). 


11



12 






can carry out repairs or rebuilds on late-model engines, but the extent of rebuilding on an early engine 

is governed by - and sometimes restricted by - parts availability. Please contact us to discuss your Mini 


wrong with your engine, but also the full engine number (if known) and type (capacity, high or low 

compression, gearbox, breathing system, etc.). The more you can give us, the better we can help you. 

Gasket Sets 

1 GUG49 GASKET SET, conversion (‘bottom end set’)1 Manual gearbox models. 

LVQ701604EVA GASKET SET, conversion (‘bottom end set’)1 Automatic gearbox models. 


water pump, front cover, front mounting plate, oil pump, oil filter head, engine to gearbox joint and 

flywheel/torque converter housing. Washers, seals and O rings are included for the following: priming 

plug, drain tap/plug, main bearing cap,front cover, distributor housing and oil suction pipe. 

EGS001 GASKET SET, full engine 1 Manual gearbox carburetter models. 

EGS002 GASKET SET, full engine 1 Manual gearbox injection models. 

A full engine gasket set includes the conversion and cylinder head gasket sets minus the head gasket 

itself, which should be purchased separately according to the engine size. 


2 AEC876 PLUG, core, cylinder block, 1 3/8" dia. 5/4 Qty. reduced from 1997 on. 

3 2K1345 PLUG, oil pressure release valve passage 2 1969-80. 

TAM2009 PLUG, oil pressure release valve passage 2 1990 on. 

For Minis with 1275cc Austin/MG Metro engines, note that TAM2009 plugs were fitted from 1985. 

4 12H1734 PLUG, oil gallery, solid brass 2 1969-80; not A Plus cylinder block. 

CAM4133 PLUG, oil gallery, cup type 4 1980-96; A Plus cylinder block. 

LYQ100120 PLUG, oil gallery 5 1997 on. 

5 RU612123 RIVET, oil way 2 1990-96. 

LYQ100080 RIVET, oil way 1 1997 on. 

6 ADP210 PLUG, oil feed 1 Automatic gearbo x. 

7 1B3664 WASHER, sealing 1 Automatic gearbo x. 

8 1A1964 RESTRICTOR, cam bearing oil feed 1 1969-96. 

TAM2056 RESTRICTOR, cam bearing oil feed 1 1997 on. 


10 CAM151 STUD, cylinder head, shor t 5/4 Qty. reduced 1990-96. 

TAM1617 STUD, cylinder head and coil bracket 1 1990-96. 

11 CHS2515 STUD, fuel pump drive aperture 2 1969-94, carburetter models. 

12 2A265 PLATE, blanking fuel pump drive aperture 1 1991-96, SPi models . 

13 GUG705557GM GASKET, blanking plate 1 1991-96, SPi models . 

14 SH505061 SCREW, blanking plate to block 2 1991-96, SPi models . 

15 LWZ205 WASHER, locking 2 1991-96, SPi models . 

16 53K615 STUD, oil filter head 2 1969-73, manual gearbo x. For paper 

element oil filters. 

CHS2613 STUD, oil filter head 2 1973-92, manual gearbo x. For ‘spin 

on’ cartridge oil filters. 

Note that from 1992-96 the filter head was attached with bolts rather than studs. Full details of oil 

filter systems and attachments are in the ‘Oil Filter and Pipes’ section of the Somerford Mini Catalogue. 

17 22A1203 PLATE, blanking oil filter aper ture 1 Automatic gearbo x. 

18 88G402 GASKET, blanking plate 1 Automatic gearbo x. 

19 SH506071 SCREW, blanking plate to block 2 Automatic gearbo x. 

20 12G1058 WASHER, sealing 2 Automatic gearbo x. 

21 12G1398 SCREW, main bearing cap to block 6 

22 12G1268 DOWEL,main bearing cap 6 

23 BHM1210 LINER SET, camshaft bearings 1 Manual gearbox. 

BHM1211 LINER SET, camshaft bearings 1 Automatic gearbo x. 

24 LDT100030 PLUG, blanking cam sensor 1 1997 on, SPi models. Includes O ring. 

25 LYX100320 O RING, blanking plug 1 1997 on, SPi models. 

26 FS106161 SCREW, plug to block 1 1997 on, SPi models. 

27 WC600041 WASHER, plain 1 1997 on, SPi models. 

28 53K2853 PLUG, cooling system drain 1 1969-96. 

29 6K638B WASHER, sealing plug 1 Use with drain plug. 

30 3H576 TAP, cooling system drain 1 Alternative to plug (not std. fitment). 

31 2K4954B WASHER, fibre, drain tap A/R Use with drain tap. 



32 12A1136 HOUSING, distributor 1 1969-80; not A Plus cylinder block. 

33 13H2792 O RING, housing 1 1969-80; not A Plus cylinder block. 

34 SH604061 SCREW, housing to block 2 1969-80; not A Plus cylinder block. 

35 LWZ404 WASHER, shakeproof 2 1969-80; not A Plus cylinder block. 


36 AEG161 PLATE, engine front mounting 1 1969-74; ‘duplex’ timing chain. 

37 12G2626 PLATE, engine front mounting 1 1974 on; ‘simplex’ chain and tensioner. 

38 GUG705554GM GASKET, plate to block 1 1969-96. 

GUG705554MPI GASKET, plate to block 1 1997 on. 



41 AEA687 SCREW, plate to main bearing cap 2 1969-74; ‘duplex’ timing chain. 

42 53K2016 SCREW, plate to main bearing cap 2 1974 on; ‘simplex’ chain and tensioner. 

43 WF600041 WASHER, shakeproof 2 1974 on; ‘simplex’ chain and tensioner. 


45 SH604061 SCREW, plate to block 3 1969-96. 

46 WF600040 WASHER, shakeproof 3 1969-96. 

47 TAM1173 SCREW, plate to block 3 1997 on. 

Timing Cover 1969-74 (‘duplex’ chain without tensioner pad) 

48 12G2506 COVER, front, timing, without oil separator 1 1969-71; includes oil seal. 

49 12G2507 COVER, front, timing, with oil separator 1 1971-74; includes oil seal. 

50 88G561 OIL SEAL, timing cover 1 Included in timing covers. 


52 SH604031 SCREW, cover to mounting plate 6 






Timing Cover 1974-96 (‘simplex’ chain with tensioner pad) 

58 12G2623 COVER, front, timing, with oil separator 1 1974-80; with oil seal. 

59 CAM4868 COVER, front, timing, with oil separator 1 1980-91; carburetter models (A Plus 

type). With oil seal. 

LJR10168 COVER, front, timing, with oil separator 1 1991-96 (SPi models 1991-96 and 

carb models 1992-94). With oil seal. 

60 88G561 OIL SEAL, timing cover 1 Included in 12G2623 and CAM4868 

timing covers. 

LUF10006 OIL SEAL, timing cover 1 Included in LJR10168 timing cover. 


62 SH604031 SCREW, cover to mounting plate 6 







Timing Cover 1997 On (‘simplex’ chain with tensioner pad) 

69 LJR103470 COVER, front, timing, with oil separator 1 1997 on; includes oil seal. 

70 LUF10006 OIL SEAL, timing cover 1 Included in timing cover. 


72 ADU6863 SCREW, cover to mounting plate 6 

73 ADU6864 WASHER, locking 6 

74 ADU8159 SCREW, cover to block or mounting plate 5 


75 2K4994 PLUG, priming 1 1969-80; not A Plus cylinder block. 

76 6K464 WASHER, sealing 1 1969-80; not A Plus cylinder block. 



The ball above may be used in place of the standard fitment plunger to guard against a sticking relief 

valve (something that the plunger is prone to do, given dirt or metal particles in the oil). It must, 

however, be used in conjunction with the shorter and stronger AEA536 spring. 

79 6K853 SPRING, oil pressure relief valve 1 Standard fitment. 

AEA536 SPRING, oil pressure relief valve 1 Uprated fitment. 




83 12A1263 DIPSTICK, oil level 1 1969-93, manual gearbox. 

LQM100380 DIPSTICK, oil level 1 1993-96, manual gearbox. 

84 12A1262 WASHER, sealing dipstick 1 1969-96, manual gearbox. 

85 12A1261 TUBE, dipstick, metal 1 1969-80; manual gearbox. Not A Plus 

cylinder block. 

86 LQM100630 DIPSTICK, oil level 1 1997 on, manual gearbox. 

For the dipstick on Minis with automatic gearboxes, please see the ‘Automatic Transmission - Torque 

Converter and Housing’ section in the Transmissions area of the Somerford Mini catalogue. 


External Engine - 970, 1071 and 1275cc (Cooper S) 


14 




970, 1071 and 1275cc Cooper S 

Engine Identification 

The big bore A Series engine, of which by far the most common variant was the 1275cc unit, was 

initially developed specifically for the Cooper S, although in modified forms it later saw use in large 

numbers in other BMC, Leyland and Austin Rover vehicles as well as other Minis. Rather than drawing on 

the 848cc Mini engine for its parentage, it was in fact developed from the 948cc A Series (of which 

there were never any transverse versions) previously seen in such cars as the Morris Minor, Austin A35 

and Austin Healey Sprite. 

The first incarnation of the big bore A Series engine was the 1071cc Cooper S unit, introduced in 1963 

and produced for just 18 months. It was joined in early 1964 and eventually replaced by the very 

popular 1275cc engine, which ran all the way through to the demise of the Cooper S in 1971. 

Additionally, the competitions-intended ‘homologation special’ 970cc engine, sharing most of its features 

with its larger capacity siblings, was produced for just under a year between 1964 and 1965. These 

three Cooper S engines are almost unique in A Series engine history in that they were never fitted in 

any other model of car. It is important to note therefore that the 1275cc Cooper S unit is quite 

different to engines of the same capacity used in later Minis. The latter ‘solid wall block’ (i.e. without 

tappet chest covers) 1275 engines are described in the ‘External Engine - 1275cc (Not Cooper S)’ section 

of the Somerford Mini catalogue. 

Upon opening the bonnet, the most obvious feature denoting the presence of a Cooper S power unit is 

the so-called ‘eleven stud’ cylinder head, technically a misnomer because the head is fixed to the block 

by ten studs and a bolt (the norm for an A Series engine is nine studs). The extra two fixings are at 

either end of the rocker cover and impinge slightly on the rocker cover’s sealing flange. Do not take 

this feature on its own as evidence of a genuine Cooper S engine, however - a small number of other 

BMC and Leyland products like the Austin/Morris 1300 GT also had the ‘eleven stud’ head. 

There are a myriad of other easily recognisable features which make up a Cooper S engine, like the 

aforementioned tappet chest covers which are not present on any other big bore A Series and, once the 

inside of the engine is open to inspection, the main bearing caps being secured by studs and nuts rather 

than the usual bolts (in 970 and 1275cc units; 1071cc used unique bolts). Of course there was also the 

fabled EN40B nitrided steel crankshaft, unique to Cooper S engines but not fitted to all Cooper S engines: 

it was quietly dropped to save costs in 1969, leaving engines produced in the last couple of years to 

‘make do’ with the still pretty desirable tuftrided EN16 crankshaft shared, again, with the Austin/Morris 

1300 GT. 


establishing which replacement parts to fit to it. The 970, 1071 and 1275cc engine number prefixes 

used on Mini Cooper S engines are listed here for that reason. Care should however be taken when 

dealing with 1071cc engine numbers as until the end of 1963 both their prefix codes and serial 

numbers coincide with those allocated to Cooper 997cc engines! 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 always relates to the compression ratio of the engine. Cooper S engines 

were always classified as high compression, but depending on capacity different compression ratio codes 

were issued: X for 970cc (10:1 CR), H for 1071cc (9:1 CR) and Y for 1275cc (9.75:1 CR). No 

compression ratio code was shown on ’12H’ type engine numbers used between 1969 and 1971. 









Cooper S Engine Serial Number Prefix Codes 

9F/SA/X 970cc engine without closed circuit breathing (1964) 

9FD/SA/X 970cc engine with closed circuit breathing (1964) 

9FE/SA/X 970cc engine with closed circuit breathing and warning switch type oil filter head (1964) 

9F/SA/X 970cc engine, specification as 9FE/SA/X. Code letter ‘E’ dropped for remainder of production 

(1964-65) 

9F/SA/H 1071cc engine without closed circuit breathing (1963-64) 

9FD/SA/H 1071cc engine with closed circuit breathing (1964) 

9F/SA/Y 1275cc engine without closed circuit breathing (1964) 

9FD/SA/Y 1275cc engine with PCV valve closed circuit breathing (1964) 

9F/SA/Y 1275cc engine with PCV valve closed circuit breathing. Code letter ‘D’ dropped for remainder 

of production (1964-68) 

9F/XE/Y 1275cc engine with PCV valve closed circuit breathing and 4 synchro gearbox (1968-69) 

12H/397/ 1275cc engine with carburetter crankcase closed circuit breathing, 4 synchro gearbox, EN16 

crank and dynamo (1969-71) 

12H/398/ 1275cc engine with carburetter crankcase closed circuit breathing, 4 synchro gearbox, EN16 

crank and alternator (1969-71) 

BMC/Leyland/Unipart Cooper S 


8G38 970cc engine without closed circuit breathing (1964) 

8G41 970cc engine with closed circuit breathing (1964) 

8G46 970cc engine with closed circuit breathing and warning switch type oil filter head (1964-65) 

8G133 1071cc engine without closed circuit breathing (1963-64) 

8G153 1071cc engine with closed circuit breathing (1964) 

8G145 1275cc engine without closed circuit breathing, with AEG148 camshaft (1964) 

8G154 1275cc engine with PCV valve closed circuit breathing and AEG148 camshaft (1964) 

8G155 1275cc engine with PCV valve closed circuit breathing, AEG148 camshaft and warning switch 

type oil filter head (1964-66) 

8G174 1275cc engine with PCV valve closed circuit breathing, AEG510 camshaft and warning switch 

type oil filter head (1966-69) 

38G464 1275cc engine with carburetter crankcase closed circuit breathing, AEG542 camshaft and EN16 

crankshaft (1969-71) 

The last number,38G464, became by the mid-1970s a ‘one spec. fits all’ engine, superseding all previous 

1275cc Cooper S reconditioned engine specifications. However, it still usually contained an AEG542 

camshaft and EN16 crankshaft. 



can carry out repairs or rebuilds on late-model engines, but the extent of rebuilding on an early engine is 

governed by - and sometimes restricted by - par ts availability. Please contact us to discuss your Mini 


wrong with your engine , but also the full engine number (if known) and type (capacity, high or low 

compression, gearbox, breathing system, etc .). The more you can provide us with, the better we can 

ascertain how we might possibly help you. 

Gasket Sets 

1 GUG49 GASKET SET, con version (‘bottom end set’) 1 

A conversion gasket set (often called ‘bottom end’ or ‘supplementary’ sets) includes gaskets for the 

following: water pump, front cover, tappet chest covers, front mounting plate, oil pump, oil filter head, 

engine to gearbox joint and flywheel/torque converter housing. Washers, seals and O rings are included 

for the following: priming plug, drain tap/plug, main bearing cap, front cover, tappet chest covers, 

distributor housing and oil suction pipe. Note that the tappet chest cover gaskets included are the post- 

1966 rubber type - customers requiring the earlier cork gaskets should purchase them separately. 

EGS001 GASKET SET, full engine 1 

The full engine gasket set includes the conversion gasket set listed above plus a cylinder head gask et set 

(‘decoke’ or ‘decarbonising’ set) minus the head gasket itself, which should be purchased separately 

according to the engine size. 


2 AEH592 PLUG, core, cylinder block, 1 41/64" dia. 4 

3 2K1345 PLUG, oil pressure release valve passage 2 

4 12H1734 PLUG, oil gallery 2 

5 AEG183 PLUG, tapered, tappet chest 2 




9 AEA684 INSERT, helicoil, cylinder head bolt 1 If required. 

The fuel pump drive aperture is not present on the vast majority of Cooper S cylinder block castings . In 

fact,we’ve never seen one with the aperture, but the original 1960s Cooper parts books consistently list 

the blanking plate for it, so perhaps it was present on some engines. However, even when it isn’t there, 

one of the studs which would have been used to secure the aperture blanking plate is still fitted - 

primarily to hold the vent pipe on open circuit breathing engines, but also sometimes used to secure an 

engine size identification plate. 

10 CHS2513 STUD, fuel pump drive aperture 2/1 Qty. 1 required if fuel pump drive 

aperture is not present. 

11 2A265 PLATE, blanking fuel pump drive aperture 1 Not required if fuel pump drive 


12 GUG705557GM GASKET, blanking plate 1 Not required if fuel pump drive 


13 FNZ105 NUT, blanking plate to block 2/1 Qty. 1 required if fuel pump drive 


14 LWZ205 WASHER, locking 2/1 Qty. 1 required if fuel pump drive 


15 PWZ105 WASHER, plain 1 Required for open circuit breathing 

vent pipe bracket (if fitted). 

16 53K615 STUD, oil filter head 2 

All Cooper S engines were originally fitted with paper element type oil filter heads. In order to fit a 

‘spin-on’ car tridge type filter head,the 53K615 mounting studs must be replaced with CHS2613 studs. 


15



16 Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk



External Engine Components (continued) 

One of the more widely known characteristics of the Cooper S engine block is the use of studs rather 

than screws or bolts to secure the main bearing caps. This is only partly true, however - the earliest 

variant of the Cooper S engine, the 1071cc unit, used screws (which are not the same as those used in 

small bore Mini engines). 

17 AEG156 SCREW, main bearing cap to block 6 1071cc . 

18 AEG205 LOCK TAB, main bearing cap screw 6 1071cc . 

19 12G478 STUD, main bearing cap to block, 4 970 and 1275cc. 

front and rear 

20 AEG323 STUD, main bearing cap to block, centre 2 970 and 1275cc. 

21 AEG417 NUT, main bearing cap 6 970 and 1275cc. 

22 BHM1210 LINER SET, camshaft bearings 1 

Cam bearings are simply pressed into the cylinder block. There is no positive location, their security 

relying on the interference fit between the bearings and the bores in the block. A good tip when 

installing cam bearings is to use a little engineering adhesive like Loctite to further hold them in 

position, guarding against migration of a bearing along the camshaft (an immediate symptom of which 

would be a jammed tappet, resulting in a valve stuck open). 

It is absolutely vital to ensure that the bearing oil holes are aligned with (and remain aligned with) the 

oil holes in the cylinder block during and after fitting. It therefore follows that a controlled method of 

pressing in the bearings is necessary and this may be achieved most effectively by using a proper cam 

bearing replacement tool and the correct adaptors - a local engine workshop will do the job for you if 

you can’t beg, borrow or steal the tool to do it yourself. Lastly,once installed, check the finished bore 

size to ensure that the camshaft will be able to rotate freely. 

23 3H576 TAP, cooling system drain 1 Standard fitment 1963-69. 

24 2K4954B WASHER, fibre, drain tap A/R Use with drain tap. 



25 53K2853 PLUG, cooling system drain 1 Standard fitment 1969 on. 

Alternative to drain tap. 

26 6K638B WASHER, sealing plug 1 Use with drain plug. 




The later 12A1136 distributor housing may be fitted in place of the earlier 2A612 housing, but only if a 

13H2792 O ring is fitted with it. 

30 SH604061 SCREW, housing to block 2 

31 LWZ404 WASHER, shakeproof 2 


32 AEG161 PLATE, engine front mounting 1 




36 AEA687 SCREW, plate to main bearing cap 2 




Timing Cover 

Several timing covers were fitted in the 1960s , some with timing pointers , some without, most with 

integral lo wer stiffeners , one without. All were superseded by 1970 by 12G2506, which includes a timing 

pointer and a strong integral lo wer stiffener and does not require the stiffener 12A666 listed below. The 

plain washers PWZ104 and PWZ105 also shown below replace the original elongated washers used at 

different times on the A Series engine until the 1980s. 



42 12A666 STIFFENER, timing cover 1 Use on ear ly 1960s covers suffering 

from poor sealing. 



plate 


46 PWZ104 WASHER, plain 6/3 Qty. reduced when 12A666 stiffener is 

present. 


plate and block 


49 PWZ105 WASHER, plain 4/3 Qty. reduced when 12A666 stiffener is 

present. 


50 - COVER, tappet chest,LH, with 1 Convex cover; for open circuit 

breather pipe breathing (1963-64). 

51 - COVER, tappet chest,LH, with 1 Concave replacement cover; for open 

breather pipe circuit breathing (1963-64). 

52 12G577 COVER, tappet chest,LH, with 1 Convex cover; for closed circuit 

oil separator breathing (1964-66). 

53 12A1212 COVER, tappet chest,LH, with 1 Concave cover; for closed circuit 

oil separator 

breathing (1966 on). 

There are too many varieties of LH tappet chest cover for open circuit engine breathing models to list 

here. However they are all detailed, along with all of the other components of each type of breathing 

system,in the ‘Emission Controls - Engine Breathing’ sections in the Fuel and Exhaust Systems area of the 

Somerford Mini catalogue. 








61 12A1177 WASHER, cup 1 For concave type cover. 

62 12A1176 BUSH, r ubber 1 For concave type cover. 

63 MRC1980A BUSH, r ubber 1 Later design; replaces 

12A1176 and 12A1177. 





67 BLS916 BALL, oil pressure relief valve 1 Alternative; see note 

below. 

The transverse A Series engine is quite susceptible to a sticking oil pressure relief valve because its 

lubricating oil is shared with the gearbox. The oil pressure relief valve comes before the oil filter in the 

lubricating system; consequently dirty, unfiltered oil is drawn by the oil pump straight from the gearbox 

into the relief valve, bringing with it fine metallic particles from the gearbox (incidentally, some metallic 

particles are not removed by the filter anyway and make their way into the rest of the engine: never 

skimp on Mini oil changes!). Almost invariably, if the valve is going to stick it will do so in the wide 

open position when the oil is cold and thick. As the oil warms it gets thinner ; because the valve is still 

stuck wide open the oil pressure drops alarmingly - the oil pump can’t keep up with thin oil and a wide 

open valve - and the engine ceases to be lubricated correctly. 

The BLS916 ball listed above may be used in place of the standard fitment plunger to guard against a 

sticking relief valve. It must, however, be used in conjunction with the Cooper/Cooper S relief valve spring 

AEA536,not with the longer (but weaker) spring used in non-Cooper engines . 

While we’re on the subject of oil pressure, if you are preparing a fast road or competition engine you can 

of course increase the oil pressure by fitting an adjustable relief valve (which Somerford Mini are not 

particular ly in favour of, as it happens, because in our experience many seem prone to leakage) or 

inserting suitable packing behind the relief valve spring. 

Don’t get carried away, though. Doubling the running oil pressure - A Series engines are set up when new 

to run between 40 and 50 lb/sq. in. approximately when warm - will result in no more effective 

lubrication than a more moderate increase to about 60 lb/sq.in. What you’re likely to get by greatly 

increasing the oil pressure (if you remember Physics lessons at school) is an unacceptable increase in oil 

temperature and let’s face it, Mini engines are not the easiest to keep cool in the first place. In extreme 

cases the oil will lose its viscosity to the point where it ceases to function effectively - hardly the desired 

outcome from raising the oil pressure. 

68 AEA536 SPRING, oil pressure relief valve 1 




Dipsticks and dipstick tubes are matched items. If your engine has a nylon dipstick tube (always called - 

and used as - a peashooter by wayward storesmen in dealers’ par ts departments!), a 12A116 dipstick 

should be fitted. A metal dipstick tube requires a 12A1263 dipstick. 

72 12A116 DIPSTICK, oil level 1 1963-66. 

12A1263 DIPSTICK, oil level 1 1966 on. 

73 AEC671 WASHER, sealing dipstick 1 1963-66. 

12A1262 WASHER, sealing dipstick 1 1966 on. 

74 12G107 TUBE, dipstick, nylon 1 1963-66. 

12A1261 TUBE, dipstick, metal 1 1966 on. 


17

Internal Engine - 848 and 997cc 


18 




Pistons, Piston Rings and Cylinder Liners 

Note before ordering a piston set or ring set from Somerford Mini: a set of pistons consists of four 

pistons complete with rings and gudgeon pins; a set of rings consists of sufficient rings for four pistons. 

Cylinder liners are supplied individually. Various piston upgrades (superior design and manufacture, 

different capacities and compression ratios) are also a vailable from Somerford Mini, but are only listed in 

this catalogue in instances where they make a good, complication-free replacement for original 

specification pistons which are in short supply. 

848cc 

1 12A120STD PISTON SET, original 4 ring type 1 Set of 4, standard size. 

12A120020 PISTON SET, original 4 ring type 1 Set of 4, +0.020" oversize. 




15037STD PISTON SET, replacement 5 ring type 1 Set of 4, standard size. 

15037020 PISTON SET, replacement 5 ring type 1 Set of 4, +0.020" oversize. 




2 BHM1161STD RING SET, for original 4 ring pistons 1 4 piston set, standard size. 

BHM1161020 RING SET, for original 4 ring pistons 1 4 piston set, +0.020" oversize. 




R8577STD RING SET, for replacement 5 ring pistons 1 4 piston set, standard size. 

R8577020 RING SET, for replacement 5 ring pistons 1 4 piston set, +0.020" oversize. 




997cc 

3 12A212STD PISTON SET, original 4 ring type 1 Set of 4, 9:1 CR; standard size. 

12A212010 PISTON SET, original 4 ring type 1 Set of 4, 9:1 CR; +0.010" oversize. 




12A406STD PISTON SET, original 4 ring type 1 Set of 4, 8.3:1 CR; standard size. 

12A406010 PISTON SET, original 4 ring type 1 Set of 4, 8.3:1 CR; +0.010" oversize. 




4 12A214STD RING SET, pistons 1 4 piston set, standard size. 

12A214010 RING SET, pistons 1 4 piston set, +0.010" oversize. 




5 2A837 PIN, gudgeon 4 Included in piston sets. 

6 12G164 LINER, cylinder 4 848cc , standard size. 

12A391 LINER, cylinder 4 997cc , standard size. 

Connecting Rods and Crankshaft 

Connecting Rods 

In 1981 the connecting rod big end cap screw was changed to an improved stretch bolt design which no 

longer required a lock tab to ensure it was secured in place. New connecting rod assemblies are most 

likely to include stretch bolts , although ‘new old stock’ rods with bolts and lock tabs that have been 

gathering dust in a corner of a store for man y years may still surface from time to time. When 

reassembling an engine, make sure all big end caps are secured by the same bolt design. 

7 12A1626 ROD ASS’Y, connecting, nos 2 and 4 2 


9 12G2217 BOLT, connecting rod cap (‘big end’) 8 1959-81; see note above. 

10 2A660 LOCK TAB, bolt 4 1959-81; see note above. 

11 CAM6126 BOLT, connecting rod cap (‘big end’) 8 1981 on; see note above. 

12 51K1382 SCREW, clamping gudgeon pin 4 


14 8G2198STD BEARING SET, connecting rod 1 Set of 4 pairs, standard size. 

(‘big end bearings’) 

8G2198010 BEARING SET, connecting rod 1 Set of 4 pairs, 0.010" undersize . 






8G2198040 BEARING SET, connecting rod 1 Set of 4 pairs, 0.040" undersize. 


Crankshaft 

Crankshafts shown here are either assemblies (including main bearings , connecting rod bearings and thr ust 

washers), or bare (without bearings or thrust washers). However, please note that new crankshafts may 

be supplied complete with bearings but other times not, depending on what is available at the time . 

Additionally Somerford Mini can offer a crankshaft regrinding service, usually carried out on your old unit. 

You should enquire on the current status of supply before ordering a crankshaft from Somerford Mini. 

For details of the primary gear and its oil-fed bushes or Deva bushes located on the tail of the 

crankshaft,please see the ‘Manual Gearbox - Primary, Idler and Drive Gears’ section or the ‘Automatic 

Transmission - Torque Converter and Housing’ section in the Transmissions area of the Somerford Mini 

catalogue. 

Finally, note that many oil-fed bush type crankshafts have been converted to the later Deva bush 

operation (using a different primary gear), so the safest way of identifying your old crankshaft is by 

finding and making a note of its stamped number. This isn’t totally infallible if you have a 997cc 

crankshaft;the raw 12A298 crankshaft was machined both for the initial (and completely defunct) ‘D.U.’ 

bush primary gear system and the Deva bush type. If you have a 12A298 crank, measuring the machined 

tail diameter will determine what you have: 1 3/8" for D.U. bush, 1 1/2" for Deva bush. 

15 28G113 CRANKSHAFT ASS’Y, with bearings, 1 848cc 1959-62. Stamped no. 22A62. 

oil-fed bush type, 1 3/8" tail diameter 

28G179 CRANKSHAFT ASS’Y, with bearings, 1 848cc 1962-63. Stamped no. 22A298. 

Deva bush type, 1 3/8" tail diameter 




oil-fed bush type, 1 3/8" tail diameter 



16 22A62 CRANKSHAFT,bare, oil-fed bush type, 1 848cc 1959-62. Stamped no. 22A62. 

1 3/8" tail diameter 

22A298 CRANKSHAFT,bare, Deva bush type, 1 848cc 1962-63. Stamped no. 22A298. 




12A375 CRANKSHAFT,bare, oil-fed bush type, 1 997cc 1961-62. Stamped no. 12A375. 




17 22A123 PLUG, crankshaft, brass 1 For oil-fed bush type crankshafts . 

18 12A604 PLUG, primary gear oilway 1 For oil-fed bush type crankshafts when 

converted to Deva bush. 

There are two distinct main bearing designs: 8G2177 bearings have a crankshaft journal width of 1.192" 

(30.28mm),whereas 8G2332 bearings have a width of 1.067" (27.1mm). The wider 8G2177 type fit 

848cc engines built between 1959 and 1969 (engine number prefixes 8A, 8MB, 8AM, 8AH, 8AJ, 8AK, 8WR), 

whereas 8G2332 bearings fit all 997cc engines, plus 848cc engines built from 1969 onwards (engine 

number prefix 85H). 

19 8G2177STD BEARING SET, main bearings, 1 848cc 1959-69, std. size. 

set of 3 pairs 

8G2177010 BEARING SET, main bearings, 1 848cc 1959-69, 0.010" undersize. 








8G2332STD BEARING SET, main bearings, 1 848cc 1969 on, 997cc; std. size. 


8G2332010 BEARING SET, main bearings, 1 848cc 1969 on, 997cc; 0.010" 


undersize. 



undersize. 



undersize. 



undersize. 




20 




Crankshaft (continued) 

Thrust washers are supplied as a pair; i.e. one upper and one lower thrust washer. Two pairs are 

required per engine, fitted selectively to obtain the correct amount of end float on the crankshaft. The 

correct time to measure the crankshaft end float (fore-aft movement) is before the main bearing caps 

are tightened down during reassembly. The end float should be between 0.001” and 0.005” (0.025mm 

to 0.127mm); usually a combination of standard and/or +0.003” oversize thr ust washers will suffice. 

20 BHM1291STD THRUST WASHERS, crankshaft, pair A/R 848cc , standard size. 

BHM1291003 THRUST WASHERS, crankshaft, pair A/R 848cc , +0.003" oversize. 


BHM1292STD THRUST WASHERS, crankshaft, pair A/R 997cc , standard size. 



21 6K836 KEY, Woodr uff, crankshaft 1 

22 8G725 GEAR, timing chain, crankshaft 1 848cc . 

AEA538 GEAR, timing chain, crankshaft 1 997cc . 

23 6K628 WASHER, packing A/R 

24 12A1148 OIL THROWER, crankshaft 1 

25 88G561 OIL SEAL, timing cover 1 Included in timing co ver assembly. 

Crankshaft Pulley 

The 848cc engine was never fitted with a vibration damper type pulley. The 997cc unit did receive one, 

or in fact two different ones. The original design was a separate pulley with a damper screwed to it; 

eventually a one-piece damper pulley was offered as a replacement but in fact both set ups remained 

available as spares alongside each other for man y years. If you want the original pulley, it is still 

available today from Somerford Mini. 

From 1980 onwards (i.e. A Plus engines) all engines without exception used slot drive . In this system the 

camshaft has a slot in the end which engages with a spade shaped lug on the oil pump shaft. 

Pre-1980 automatic, 1969-71 Cooper S and most 1275 GT engines (i.e. not including the last handful of 

1980 built engines which were A Plus) used star drive , otherwise known as spider drive. In this system a 

drive flange or ‘spider’ sits between the camshaft and oil pump, its three external lobes engaging in the 

end of the camshaft and its internal splines (or ‘star’) engaging on external splines on the oil pump shaft. 

A range of uprated camshafts and other engine tuning components are also available from Somerford Mini, 

but are not listed here. Please contact us for details. 

38 8G712 CAMSHAFT, for ‘pin drive’oil pump 1 848cc, manual gearbox, 1959-80. 

CAM6267 CAMSHAFT, for ‘slot drive’oil pump 1 848cc, manual gearbox, 1980 on. 

A Plus type. 

12A1065 CAMSHAFT, for ‘star drive’ oil pump 1 848cc, automatic gearbox. 

88G229 CAMSHAFT, for ‘pin drive’oil pump 1 997cc . 

39 2A299 PIN, oil pump drive 1 Included in ‘pin drive’type camshafts. 

40 CHM108 FLANGE, for ‘star drive’ oil pump 1 Use with ‘star drive’ type camshaft. 

(flange also known as ‘spider’) 

41 12G4499 SPINDLE, distributor drive 1 

42 2A13 TAPPET (also known as cam follower) 8 Standard size . 

2A13010 TAPPET (also known as cam follower) 8 +0.010" oversize. 

43 2A14 PUSH ROD 8 Alternative to 12A250 when replaced 

in sets. 

12A250 PUSH ROD 8 Alternative to 2A14 when replaced 

in sets. 

Note that the bolt retaining the pulley to the crankshaft is specific to the type of pulley being fitted. 

Later ’85H’ 848cc engines from 1980 approximately onwards received a pulley with a strobe timing plate 

attached as par t of the A Plus modification programme. 

848cc Crankshaft Pulley 

26 2A940 PULLEY, crankshaft 1 1959-70, dynamo fitted models. 

12A1380 PULLEY, crankshaft 1 1959-70, alter nator fitted models. 

CAM6323 PULLEY, crankshaft 1 1970-80; may be used on earlier 

engines. 

CAM6497 PULLEY, crankshaft 1 1980 on; A Plus type with timing 

plate . 

27 AEA312 BOLT, pulley to crankshaft 1 

28 12A398 LOCK TAB, pulley bolt 1 


29 AEG454 PULLEY, crankshaft 1 Separate pulley and damper fitment. 

30 12A367 DAMPER 1 Separate pulley and damper fitment. 

31 SH605051 SCREW, damper to pulley 4 Separate pulley and damper fitment. 

32 LWZ305 WASHER, locking 4 Separate pulley and damper fitment. 

33 AEA312 BOLT, pulley to crankshaft 1 Separate pulley and damper fitment. 

34 12A398 LOCK TAB, pulley bolt 1 Separate pulley and damper fitment. 

35 88G305 PULLEY, crankshaft, with damper 1 One-piece damper pulley fitment. 

36 12A283 BOLT, pulley to crankshaft 1 One-piece damper pulley fitment. 

37 12A398 LOCK TAB, pulley bolt 1 One-piece damper pulley fitment. 

Camshaft and Tappets 

A dramatic proportion of the wear suffered by a camshaft during its entire working life actually takes 

place during the first few minutes of running after fitment. Whenever you replace the camshaft or 

tappets, or both, in your engine you should apply cam lubricant during assembly; it will lessen the 

inevitable scuffing and potential damage between cam and tappets during the bedding in period. 

Somerford Mini stock cam lube in a 250ml bottle under part number CL001. Also, you can pack the oil 

pump with cam lube before fitting it to the engine - it’s a very successful way of priming the oil pump 

(if you prime it with engine oil, there’s a fair chance a lot of it will have drained back into the gearbox 

by the time you turn the engine over for the first time). 

Three different coupling designs (‘drives’) between the end of the camshaft and the oil pump were used 

in Mini engines, and of course you will need to ensure that if the camshaft or oil pump are replaced 

that the correct matching types are used. Drive methods can be changed in engines (particularly when 

the desired profile of camshaft is not available with the original drive type for your engine), but this 

tends to get a little complicated when sorting out the correct corresponding oil pump to use. Details of 

which oil pumps may be fitted to which engines - and how they can be fitted - are in the Oil Pumps 

and Oil Pressure Relief Valves section of the Somerford Mini Catalogue. 

Up until 1980, all Mini engines - except automatic, 1969-71 Cooper S and 1275 GT units - used pin 

drive camshafts, where a pin across the end of the camshaft engages in a slot in the oil pump shaft (but 

don’t call it slot drive - that’s a different system). 

Timing Chain 

Three different timing chain gear systems were used to drive the camshaft on the 848cc engine. From 

1959 until 1974, a gear with rubber tensioner rings fitted either side was used. From 1974 to 1979 a 

different gear without tensioner rings was fitted; this gear can be used on pre-1974 engines, without 

tensioner rings. Finally from 1979 onwards a sprung tensioner pad (at last, a proper chain tensioner) 

together with the 1974-79 gear - again, without rings - was used. 

To be honest,replacement in a pre-1974 engine of the early gear and ring tensioners with the later, plain 

gear has little or no detrimental effect on timing chain efficiency or durability, since the ring tensioners 

struggle to get past a few thousand miles of running before becoming completely ineffective anyway! 

997cc engines were all originally fitted with the ring tensioner type chain gear, but as with the 848cc 

engine the later gear may be fitted instead without the rubber rings. 

44 3H2127 CHAIN, timing 1 

45 2A85 GEAR, timing chain, camshaft, with ring 1 1959-74, may be replaced by 

tensioners 

12G4337 without ring tensioners. 

46 2A86 GEAR, timing chain, camshaft, ring 1 1959-74, may be replaced by 

tensioner type 


47 12G4337 GEAR, timing chain, camshaft 1 1974-79, use without ring tensioners. 

1979 on, use with tensioner pad. 

48 8G549 RING, timing chain tensioner, rubber 2 1959-74. 

49 12G2621 PAD,timing chain tensioner 1 1979 on. 

50 12G2629 PIN, tensioner pivot 1 1979 on. 

51 12G2628 PLATE, tensioner mounting 1 1979 on. 

52 SH605061 SCREW, plate to cylinder block 2 1979 on. 

53 LWZ305 WASHER, locking 2 1979 on. 

54 PWZ105 WASHER, plain 2 1979 on. 

55 WKN505 KEY, Woodr uff 1 

56 6K629 NUT, gear to camshaft 1 

57 2A759 LOCK TAB, nut 1 

Interchangeability of Timing Chain Assemblies 

It is perfectly possible to uprate the camshaft drive on earlier, simplex (single row) chain type engines by 

using standard components from other A Series or A Plus engines. The one slight modification required 

would be when fitting a duplex (double row) chain and gears, in which case the two screw holes in the 

engine front plate corresponding with the front main bearing cap will need to be countersunk. 

To convert from a plain simplex chain to a simple x chain with sprung pad tensioner (as on A Plus 

engines), you will need camshaft gear 12G4337 (if your engine is pre-1974), engine front plate 12G2626, 

A Plus timing cover CAM4904, timing cover gasket GUG705550GM, an extra screw, lock washer, plain 

washer and nut to secure the cover (part nos. SH605061, LWZ305, PWZ105 and FNZ105 respectively), plus 

the sprung pad tensioner assembly listed in illustration numbers 49 to 54 abo ve. 

To convert from a simplex to duplex chain, the only different parts you will require are camshaft gear 

AEA696 (steel) or 12G1397 (iron),crankshaft gear AEA695 (steel) or 12G1699 (iron), duplex chain 

2H4905 and two off front plate to main bearing cap countersunk screw AEA687. 




22 






pistons with rings and gudgeon pins; a set of rings consists of rings for four pistons . Cylinder liners are 

supplied individually. Various piston upgrades (superior design and manufacture, different capacities and 

compression ratios) are also available from Somerford Mini, but are only listed in this catalogue where 

they make a good, complication-free replacement for original specification pistons in shor t supply. 

998cc 1963-80 (not Cooper) 

4 Ring Piston With 0.125" Thick Double Bevelled Oil Ring 

1 12A673STD PISTON SET, set of 4, dished piston crown 1 8.3:1 compression ratio, standard size. 

12A673020 PISTON SET, set of 4, dished piston crown 1 8.3:1 comp. ratio, +0.020" oversize. 




2 BHM1162STD RING SET, 4 piston set 1 Standard size . 

BHM1162020 RING SET, 4 piston set 1 +0.020" oversize . 




998cc 1963-69 (Cooper) 

4 Ring Piston 

The 9:1 compression ratio pistons have been out of production for many years and supply is almost nonexistant. 

The Powermax pistons listed further do wn the page are most often supplied as replacements. 

9 12A674STD PISTON SET,set of 4, raised ‘D’ crown 1 9:1 comp. ratio,standard size. 

12A674020 PISTON SET,set of 4, raised ‘D’ crown 1 9:1 comp. ratio, +0.020" oversize. 




12A593STD PISTON SET, set of 4, dished piston crown 1 8.3:1 comp. ratio, standard size. 

12A593020 PISTON SET, set of 4, dished piston crown 1 8.3:1 comp. ratio, +0.020" oversize . 





BHM1162020 RING SET, 4 piston set 1 +0.020" oversize. 




998cc 1980-84 (A Plus) 

4 Ring Piston With 0.158" Thick Special Oil Ring 

3 ADU3920STD PISTON SET, set of 4, flat piston crown 1 10.3:1 comp. ratio, standard size. 

ADU3920020 PISTON SET, set of 4, flat piston crown 1 10.3:1 comp. ratio, +0.020" oversize. 




ADU3922STD PISTON SET, set of 4, dished piston crown 1 8.3:1 comp. ratio, standard size. 

ADU3922020 PISTON SET, set of 4, dished piston crown 1 8.3:1 comp. ratio, +0.020" oversize. 









998cc 1984-88 (A Plus) 

3 Ring Piston With Gudgeon Pin Retained By Circlips 

5 ADU3490STD PISTON SET, set of 4, flat piston crown 1 10.3:1 comp. ratio, standard size. 





ADU4203STD PISTON SET, set of 4, dished piston crown 1 8.3:1 comp. ratio, standard size. 










998cc 1988 On (A Plus) 

3 Ring Piston With Press Fit Gudgeon Pin 

7 TAM2052STD PISTON SET, set of 4, flat piston crown 1 10.3:1 comp. ratio, standard size. 

TAM2052020 PISTON SET, set of 4, flat piston crown 1 10.3:1 comp. ratio, +0.020" oversize. 




TAM2054STD PISTON SET, set of 4, dished piston crown 1 8.3:1 comp. ratio, standard size. 

TAM2054020 PISTON SET, set of 4, dished piston crown 1 8.3:1 comp. ratio, +0.020" oversize. 









998cc 1963-69 (Cooper) 

3 Ring Powermax Piston 

11 20950STD PISTON SET, set of 4, flat piston crown 1 9.7:1 comp. ratio, standard size. 

20950020 PISTON SET, set of 4, flat piston crown 1 9.7:1 comp. ratio, +0.020" oversize . 



12 R39400STD RING SET, 4 piston set 1 Standard size . 

R39400020 RING SET, 4 piston set 1 +0.020" oversize. 



1098cc 1975-80 

4 Ring Piston With 0.125" Thick Double Bevelled Oil Ring 

13 12G758STD PISTON SET, set of 4, dished piston crown 1 8.5:1 comp. ratio, standard size. 

12G758020 PISTON SET, set of 4, dished piston crown 1 8.5:1 comp. ratio, +0.020" oversize . 









1098cc 1980-81 (A Plus) 

4 Ring Piston With 0.158" Thick Special Oil Ring 

15 BAU4418STD PISTON SET, set of 4, dished piston crown 1 8.5:1 comp. ratio, standard size. 

BAU4418020 PISTON SET, set of 4, dished piston crown 1 8.5:1 comp. ratio, +0.020" oversize . 









17 CCN210 CIRCLIP, gudgeon pin 8 Not 998cc 1988 on. 

18 12G164 LINER, cylinder 4 Standard size . 


Connecting Rods 1963-88 

(Gudgeon Pin Retained By Circlips) 

In 1981 the connecting rod big end cap screw was changed to an improved stretch bolt design which no 

longer required a lock tab. New connecting rod assemblies are most likely to include stretch bolts, 

although ‘new old stock’ rods with bolts and lock tabs may still surface from time to time. When 

reassembling an engine, make sure all big end caps are secured by the same bolt design. 

19 12G123 ROD ASS’Y, connecting, nos 2 and 4 2 

20 12G126 ROD ASS’Y, connecting, nos 1 and 3 2 

21 12G125 BUSH, small end 4 Included in rod assembly. 

22 12G2217 BOLT, connecting rod cap, big end 8 1963-81; see note above. 

23 2A660 LOCK TAB, bolt 4 1963-81; see note above. 

24 CAM6126 BOLT, connecting rod cap, big end 8 1981-88; see note above. 




24 




Connecting Rods and Crankshaft (continued) 

Connecting Rods 1988 On 

(Press Fit Gudgeon Pin) 



27 12G125 BUSH, small end 4 Included in rod assembly. 

28 CAM6126 BOLT, connecting rod cap, big end 8 

29 8G2198STD BEARING SET, connecting rod, big end 1 Set of 4 pairs, standard size. 

8G2198010 BEARING SET, connecting rod, big end 1 Set of 4 pairs, 0.010" undersize . 




Crankshaft 

Crankshafts shown here are either assemblies (including main bearings, connecting rod bearings and thr ust 


be supplied complete with bearings but other times not, depending on what is a vailable at the time. 



For details of the primar y gear and its bushes located on the tail of the crankshaft, please see the 

‘Manual Gearbox - Primary, Idler and Drive Gears’ section or the ‘Automatic Transmission - Torque 

Converter and Housing’ section in the Transmissions area of the Somerford Mini catalogue . 

30 8G2733 CRANKSHAFT ASS’Y (with 1963-83 main 1 998cc 1963-83. Stamped no. 12A595 

bearings) or 12A1451. 

BHM1436 CRANKSHAFT ASS’Y (with 1983 on main 1 998cc 1983 on. Stamped no. 

bearings) 12A1451. 

8G2732 CRANKSHAFT ASS’Y (with 1963-83 main 1 1098cc . Stamped no. 12G82. 

bearings) 

31 12A1451 CRANKSHAFT, bare 1 998cc . Stamped 12A1451. 

12G82 CRANKSHAFT, bare 1 1098cc . Stamped no. 12G82. 

There are two distinct main bearing designs: 8G2332 bearings have locating lugs on the edge of both 

upper and lower halves, whereas BHM1573 bearings have lugs on the edge of the upper halves and in 

the centre of the lower halves. They cannot be interchanged in engines because the engine main bearing 

caps are unique for each design. 

32 8G2332STD BEARING SET, main bearings, 3 pairs 1 998/1098cc 1963-83; std. size. 

8G2332010 BEARING SET, main bearings, 3 pairs 1 998/1098cc 1963-83; 0.010" u/size . 




BHM1573STD BEARING SET, main bearings, 3 pairs 1 998cc 1983 on; std. size. 

BHM1573010 BEARING SET, main bearings, 3 pairs 1 998cc 1983 on; 0.010" undersize. 





required per engine, fitted selectively to obtain the correct amount of end float on the crankshaft. 

33 BHM1292STD THRUST WASHERS, crankshaft, pair A/R Standard size . 

BHM1292003 THRUST WASHERS, crankshaft, pair A/R +0.003" oversize . 



35 8G725 GEAR, timing chain, crankshaft 1 998cc (not Cooper) and 1098cc . 

AEA538 GEAR, timing chain, crankshaft 1 998cc (Cooper). 





The 998cc (not Cooper) engine was not fitted with a vibration damper type pulley, whereas the 1098cc 

engine used a one-piece damper pulley. The 998cc Cooper unit also received one, or in fact two 

different ones. The original design was a separate pulley with a with a damper screwed to it; eventually 

a one-piece damper pulley was offered as a replacement but in fact both set ups remained available as 

spares for many years . If you want the original pulle y, it is still available today from Somerford Mini. 

Note that the bolt retaining the pulley to the crankshaft is specific to the type of pulley being fitted. 

Later 998cc and 1098cc engines from 1980 approximately onwards received pulleys with strobe timing 

plates attached as part of the A Plus modification programme . 

998cc (not Cooper) Crankshaft Pulley 

39 2A940 PULLEY, crankshaft 1 1963-70, dynamo fitted models. 

12A1380 PULLEY, crankshaft 1 1963-70, alternator fitted models. 

CAM6323 PULLEY, crankshaft 1 1970-80; will fit earlier engines. 

CAM6497 PULLEY, crankshaft 1 1980 on; A Plus (with timing plate). 

40 AEA312 BOLT, pulley to crankshaft 1 1963-87. 

TAM2019 BOLT, pulley to crankshaft 1 1987 on. 

41 12A398 LOCK TAB, pulley bolt 1 1963-87. 

TAM2020 LOCK TAB, pulley bolt 1 1987 on. 

998cc (Cooper) Crankshaft Pulley 











51 88G305 PULLEY, crankshaft, with damper 1 1975-76. 

CAM4929 PULLEY, crankshaft, with damper 1 1976-80; will fit earlier engines. 

AHU1878 PULLEY, crankshaft, with damper 1 1980 on; A Plus (with timing plate). 

52 12A283 BOLT, pulley to crankshaft 1 





998cc (not Cooper) Camshaft 

54 8G712 CAMSHAFT, for ‘pin drive’oil pump 1 1963-80, manual gearbox. 

12A1065 CAMSHAFT, for ‘star drive’ oil pump 1 1967-80, automatic gearbox. 

CAM6267 CAMSHAFT, for ‘slot drive’oil pump 1 1980 on, A Plus; for 8.3:1 comp. ratio. 

CAM4717 CAMSHAFT, for ‘slot drive’oil pump 1 1980 on, A Plus; for 10.3:1 comp. ratio. 

998cc (Cooper) Camshaft 

AEA630 CAMSHAFT, for ‘pin drive’oil pump 1 Alternative to 12G165. 

12G165 CAMSHAFT, for ‘pin drive’oil pump 1 Alternative to AEA630. 

1098cc Camshaft 

AEA630 CAMSHAFT, for ‘pin drive’oil pump 1 1975-80, alternative to 12G165. 

12G165 CAMSHAFT, for ‘pin drive’oil pump 1 1975-80, alternative to AEA630. 

12G2983 CAMSHAFT, for ‘slot drive’oil pump 1 1980 on, A Plus type. 




57 12G4499 SPINDLE, distributor drive , centred slot 1 1963-80. 

12G3560 SPINDLE, distributor drive , offset slot 1 1980 on, A Plus type. 

58 2A13 TAPPET (also known as cam follower) 8 Standard size . 

2A13010 TAPPET (also known as cam follower) 8 +0.010" oversize. 

59 2A14 PUSH ROD 8 Alternative to 12A250 (replace in sets). 

12A250 PUSH ROD 8 Alternative to 2A14 (replace in sets). 

Timing Chain 

60 3H2127 CHAIN, timing 1 

61 2A85 GEAR, timing chain, camshaft, 1 1963-74, may be replaced by 

with ring tensioners 


62 2A86 GEAR, timing chain, camshaft, 1 1963-74, may be replaced by 

ring tensioner type 


63 12G4337 GEAR, timing chain, camshaft 1 1974-79, use without ring tensioners. 

1979 on, use with tensioner pad. 

64 8G549 RING, timing chain tensioner, rubber 2 1963-74. 

65 12G2621 PAD,timing chain tensioner 1 1979 on. 

66 12G2629 PIN, tensioner pivot 1 1979 on. 

67 12G2628 PLATE, tensioner mounting 1 1979 on. 

68 SH605061 SCREW, plate to cylinder block 2 1979 on. 

69 LWZ305 WASHER, locking 2 1979 on. 

70 PWZ105 WASHER, plain 2 1979 on. 





Internal Engine - 1275cc (Not Cooper S) 


26 







Cylinder liners are supplied individually. Various piston upgrades (superior design and manufacture, 

different capacities and compression ratios) are also a vailable from Somerford Mini, but are only listed in 

this catalogue in instances where they make a good, complication-free replacement for original 

specification pistons which are in short supply. 

Pistons listed here are those for original 1275cc Mini engines - i.e. the 1275 GT engine built between 

1969 and 1980, plus engines fitted from the resumption of 1275cc Mini production in 1990 onwards. If 

you have a 1980s Austin or MG Metro 1275cc engine in your Mini, the later A Plus pistons shown here 

may be applicable in some circumstances, but we strongly advise you to contact Somerford Mini quoting 

your full engine number before placing an order to ensure you receive the right pistons or rings for 

your engine. 

1969-80 (1275 GT) 

8.8:1 Compression Ratio 

1 12G2088STD PISTON SET, original 4 ring type 1 Set of 4, standard size. 

12G2088020 PISTON SET, original 4 ring type 1 Set of 4, +0.020" oversize. 




21251STD PISTON SET, replacement metric 3 ring 1 Set of 4, standard size. 

type 

21251020 PISTON SET, replacement metric 3 ring 1 Set of 4, +0.020" oversize. 

type 


type 


type 


type 






R35960STD RING SET, for replacement metric 3 ring 1 4 piston set, standard size. 

pistons 

R35960020 RING SET, for replacement metric 3 ring 1 4 piston set, +0.020" oversize. 

pistons 


pistons 


pistons 


pistons 

1990 On (A Plus) 

10:1 Compression Ratio 

3 TAM2050STD PISTON SET, original metric 3 ring type 1 Set of 4, standard size. 

TAM2050020 PISTON SET, original metric 3 ring type 1 Set of 4, +0.020" oversize. 




4 BHM1628STD RING SET, for original metric 3 ring 1 4 piston set, standard size. 

pistons 

BHM1628020 RING SET, for original metric 3 ring 1 4 piston set, +0.020" oversize. 

pistons 


pistons 


pistons 


pistons 

1992 On (A Plus) 

9.4:1 Compression Ratio 

5 TAM2048STD PISTON SET, original metric 3 ring type 1 Set of 4, standard size. 





6 BHM1628STD RING SET, for original metric 3 ring 1 4 piston set, standard size. 

pistons 

BHM1628020 RING SET, for original metric 3 ring 1 4 piston set, +0.020" oversize . 

pistons 


pistons 


pistons 


pistons 

7 12G1049 PIN, gudgeon 4 Included in piston sets. 

8 AEG428 LINER, cylinder 4 Standard size . 


Connecting Rods 1969-80 (1275 GT) 

9 BHM1136 ROD SET, connecting, set of 4 1 Standard fitment. 

10 12G1506 ROD ASS’Y,connecting 4 Standard fitment; included in 

connecting rod set. 

12G1297 ROD ASS’Y,connecting 4 Alternative Austin 1300 GT/Innocenti 

item. 

The standard fitment 1275 GT connecting rod is very strong but also ver y heavy. Originally made from 

EN19, its material specification was downgraded to EN16 in 1974, at the same time as several other 

changes occurred in the engine (when the Duplex timing chain was replaced by a Simplex tensioned chain). 

Unfortunately there are no distinguishing features between the EN19 and EN16 items and the same 

forging number and part number were used for both, although it’s a fair assumption that if you come 

across new ones today they are likely to be made from EN16. 

The 1300 GT/Innocenti rod design is lighter than, but as strong as, the standard rod to be found in 1275 

GT engines. Made from EN19 material,it can be easily recognised by its forging number 12G1298 and a 

small strengthening web across the rod between its flutes (just above the forging number). Ideal for 

inclusion in a tuned engine, this rod was always historically speaking ver y popular. Somerford Mini still 

has a limited number in stock, but hurry - when they’re gone, they’re gone. 

When changing to a different design of connecting rod, it is of course imperative that all rods are 

changed at the same time. 

11 LFH10006 BOLT, connecting rod cap, big end 8 Included in connecting rod assembly. 

12 13H5872 NUT, connecting rod cap, big end 8 Included in connecting rod assembly. 

Connecting Rods 1990 On (A Plus) 

13 BHM1137 ROD SET, connecting, set of 4 1 

14 LFH10006 BOLT, connecting rod cap, big end 8 Included in connecting rod assembly. 

15 CAM6263 NUT, connecting rod cap, big end 8 Included in connecting rod assembly. 

16 8G2553STD BEARING SET, connecting rod, big end 1 Set of 4 pairs, standard size. 

8G2553010 BEARING SET, connecting rod, big end 1 Set of 4 pairs, 0.010" undersize. 




Crankshaft 



be supplied complete with bearings but other times not, depending on what is available at the time . 


You should enquire on the current status of supply before ordering a crankshaft from Somerford Mini. The 

CAM6232-stamped crankshaft forgings have rolled fillet radii between the bearing journals and webs, which 

dramatically improve their fatigue resistance over the previous crankshaft design. 

For details of the primary gear and its bushes located on the tail of the crankshaft, please see the ‘Manual 

Gearbox - Primary, Idler and Drive Gears’ section or the ‘Automatic Transmission - Torque Converter and 

Housing’ section in the Transmissions area of the Somerford Mini catalogue. 

17 8G2740 CRANKSHAFT ASS’Y (with early main 1 1275 GT 1969-80. Stamped no. 

bearings) 12G1304, 12G1683 or 12G1505. 

BHM1243 CRANKSHAFT ASS’Y (with early main 1 Replacement for 1275 GT. Stamped 

bearings) 

no. CAM6232 (with rolled fillet radii). 

BHM1437 CRANKSHAFT ASS’Y (with late main 1 A Plus 1990 on. Stamped no. 

bearings) 

CAM6232 (with rolled fillet radii). 

18 12G1505 CRANKSHAFT, bare 1 1275 GT 1969-80. Stamped no. 

12G1505. 

CAM6232 CRANKSHAFT, bare 1 A Plus 1990 on; also replacement for 

1275 GT. Stamped no. CAM6232 (with 

rolled fillet radii). 




28 




Crankshaft (continued) 

There are two distinct main bearing designs: the earlier 8G2391 bearings have locating lugs on the edge 

of both upper and lower halves, whereas the later BHM1574 bearings have lugs on the edge of the 

upper halves and in the centre of the lower halves. They cannot be interchanged in engines because the 

engine main bearing caps are unique for each design. 1275cc engines were not fitted by the factory in 

Minis during the 1980s; however many owners have chosen to transplant Austin or MG Metro 1275cc 

engines made in the 1980s into their cars. For the benefit of those owners, the change in main bearing 

design on the Metro power unit occurred in 1983. 

19 8G2391STD BEARING SET, main bearings, 1 1275 GT 1969-80; std. size. 


8G2391010 BEARING SET, main bearings, 1 1275 GT 1969-80; 0.010" undersize. 








BHM1574STD BEARING SET, main bearings, 1 A Plus 1990 on; std. size. 


BHM1574010 BEARING SET, main bearings, 1 A Plus 1990 on; 0.010" undersize. 

















22 12G1699 GEAR, timing chain, crankshaft 1 1275 GT 1969-74; for duple x chain. 

23 8G725 GEAR, timing chain, crankshaft 1 1275 GT 1974-80; A Plus 1990 on. 

For simplex chain. 

Once again, the change dates listed above apply to original Mini engines. For the sake of Mini owners 

with 1275cc Metro engines in their cars, all Metro engines have simplex timing chains. 



Three different coupling designs (‘drives’) between the end of the camshaft and the oil pump were used in 

Mini engines, and of course you will need to ensure that if the camshaft or oil pump are replaced that 

the correct matching types are used. Drive methods can be changed in engines (particularly when the 

desired profile of camshaft is not available with the original drive type for your engine), but this tends to 

get a little complicated when sorting out the correct corresponding oil pump to use. Details of which oil 

pumps may be fitted to which engines - and how they can be fitted - are in the Oil Pumps and Oil 

Pressure Relief Valves section of the Somerford Mini Catalogue. 

Up until 1980,all Mini engines - except automatic , 1969-71 Cooper S and 1275 GT units - used pin drive 

camshafts, where a pin across the end of the camshaft engages in a slot in the oil pump shaft (but don’t 

call it slot drive - that’s a different system). Pin drive camshafts are not original for the engines detailed 

in this section. 

From 1980 onwards (i.e. from the introduction of A Plus engines) all engines without exception used slot 

drive. In this system the camshaft has a slot in the end which engages with a spade shaped lug on the 

oil pump shaft. 







Camshaft 1969-80 (1275 GT) 

33 AEG523 CAMSHAFT, for ‘star drive’ oil pump 1 1969-80. 

12G2983 CAMSHAFT, for ‘slot drive’oil pump 1 1980; A Plus type. 

Camshaft 1990 On (A Plus) 

For owners with transplanted 1275cc Metro engines in their Minis, please contact Somerford Mini, quoting 

your full engine number,to ensure you receive the correct camshaft for your engine. 

CAM6648 CAMSHAFT, for ‘slot drive’oil pump 1 10:1 compression ratio carburetter 

engines. 

LGC10230 CAMSHAFT, for ‘slot drive’oil pump 1 10:1 compression ratio single point 

injection engines. 

LGC105380 CAMSHAFT, for ‘slot drive’oil pump 1 10:1 compression ratio multi point 

injection engines. 

LGC10231 CAMSHAFT, for ‘slot drive’oil pump 1 9.4:1 compression ratio carburetter 

and single point injection engines. 




Crankshaft Pulley 1969-96 

27 88G305 PULLEY, crankshaft, with damper 1 1275 GT 1969-76. 

CAM4929 PULLEY, crankshaft, with damper 1 1275 GT 1976-80; can be used to 

replace 88G305. 

AHU1878 PULLEY, crankshaft, with damper 1 1275 GT 1980; A Plus 1990-96. 

With timing plate . 

28 12A283 BOLT, pulley to crankshaft 1 1275 GT 1969-80. 

TAM2019 BOLT, pulley to crankshaft 1 A Plus 1990-96. 

29 12A398 LOCK TAB, pulley bolt 1 1275 GT 1969-80. 

TAM2020 LOCK TAB, pulley bolt 1 A Plus 1990-96. 

For Mini owners with 1980s Metro 1275cc engines in their cars, all Metro engines use the AHU1878 

pulley, TAM2019 bolt and TAM2020 lock tab. 

Crankshaft Pulley 1997 On 

30 LHF100130 PULLEY, crankshaft, with damper 1 Polyvee belt type. 

31 TAM2019 BOLT, pulley to crankshaft 1 

32 TAM2020 LOCK TAB, pulley bolt 1 










35 12G4499 SPINDLE, distributor drive , centred slot 1 1969-80. 

12G3560 SPINDLE, distributor drive , offset slot 1 1980-96, A Plus type. 

36 2A13 TAPPET (also known as cam follower) 8 1969-96; standard size. 

2A13010 TAPPET (also known as cam follower) 8 1969-96; +0.010" oversize. 

LGR100440 TAPPET (also known as cam follower) 8 1997 on; standard size. 

37 AEG314 PUSH ROD 8 

Timing Chain 

Duplex Timing Chain 1969-74 

38 2H4905 CHAIN, timing, duplex (double row) 1 

39 12G1397 GEAR, duplex timing chain, camshaft 1 




Simplex Timing Chain 1974 On 

43 3H2127 CHAIN, timing, simplex (single row) 1 

44 12G4337 GEAR, timing chain, camshaft 1 

45 12G2621 PAD,timing chain tensioner 1 

46 12G2629 PIN, tensioner pivot 1 

47 12G2628 PLATE, tensioner mounting 1 

48 SH605061 SCREW, plate to cylinder block 2 







29

Internal Engine - 970, 1071 and 1275cc (Cooper S) 


30 







Cylinder liners are supplied individually. 

Various piston upgrades (superior design and manufacture, different capacities and compression ratios) are 

also available from Somerford Mini, but are only listed in this catalogue in instances where they make a 

good, complication-free replacement for original specification pistons which are in short supply. 

1071cc (9:1 compression ra tio, dished crown) 

Original Equipment 3 and 4 Ring Pistons 

Within a very short period after the end of 1071cc engine production, the factor y discontinued the 

original 3 ring pistons in favour of a 4 ring type - actually the same pistons they were currently fitting 

in the 1275cc Cooper S engine. Today, supply of these 4 ring pistons is sketch y to say the least, and 

many owners or engine builders use Powermax pistons or replacements with metric rings (listed later on 

this page). Both of the latter revert to having 3 rings per piston, but these rings are not the same as 

the original 1071cc 3 rings and are not interchangeable with them. 

1 AEG184STD PISTON SET, original 3 ring type 1 Set of 4, standard size. 

AEG184010 PISTON SET, original 3 ring type 1 Set of 4, +0.010" oversize. 




8G2434STD PISTON SET, replacement 4 ring type 1 Set of 4, standard size. 

8G2434010 PISTON SET, replacement 4 ring type 1 Set of 4, +0.010" oversize. 




2 8G2435STD RING SET, for original 3 ring pistons 1 4 piston set, standard size. 

8G2435010 RING SET, for original 3 ring pistons 1 4 piston set, +0.010" oversize. 




BHM1165STD RING SET, for replacement 4 ring pistons 1 4 piston set, standard size. 

BHM1165010 RING SET, for replacement 4 ring pistons 1 4 piston set, +0.010" oversize. 




1275cc (9.75:1 compression ratio, dished crown) 

Original Equipment 4 Ring Pistons 











1071cc/1275cc (9:1/9.75:1 compression ra tio, dished crown) 

Replacement 3 Ring and Powermax Pistons 

5 21253STD PISTON SET, replacement metric 3 ring 1 Set of 4, standard size. 

type 


type 


type 


type 

20747STD PISTON SET, Powermax 3 ring type 1 Set of 4, standard size. 

20747020 PISTON SET, Powermax 3 ring type 1 Set of 4, +0.020" oversize. 



6 R41570STD RING SET, for replacement metric 3 ring 1 4 piston set, standard size. 

pistons 


pistons 


pistons 


pistons 

R39380STD RING SET, for Powermax 3 ring pistons 1 4 piston set, standard size. 

R39380020 RING SET, for Powermax 3 ring pistons 1 4 piston set, +0.020" oversize . 



970cc (10:1 compression ratio, flat crown) 

Original Equipment 4 Ring Pistons 

While the 1071cc and 1275cc Cooper S engines share the same dished crown pistons, the 970cc engine 

has a unique flat crown design: 


8G2432010 PISTON SET, original 4 ring type 1 Set of 4, +0.010" oversize . 





BHM1165010 RING SET, for original 4 ring pistons 1 4 piston set, +0.010" oversize . 




9 AEG189 PIN, gudgeon 4 Included in piston sets. 

10 AEG428 LINER, cylinder 4 Standard size . 


Connecting Rods 

Telling a 970cc connecting rod apart from the 1071/1275cc item is a matter of measuring the distance 

between small and big end centres: at 5 7/8" the 970cc rod is 1/8" longer than that used in the larger 

capacity engines. The two different material rods appropriate both for the 1071 and 1275cc engines are 

identical in design but can be distinguished by the forging numbers displayed: AEG177 or AEG521 for an 

AEG520 rod,and AEG625 for an AEG624 rod. AEG624 is a good substitute for the original AEG520 rod 

(it was developed for the 1275cc MG Midget/Austin Healey Sprite engine), but as always make sure all 

four you intend to use are the same! 

11 AEG520 ROD ASS’Y, connecting (marked AEG177 4 1071 and 1275cc; original EN24V 

or AEG521) 

material. 

AEG624 ROD ASS’Y, connecting (marked AEG625) 4 1071 and 1275cc; replacement in 

EN21 material. 

AEG309 ROD ASS’Y,connecting 4 970cc . 

12 AEG519 BOLT, connecting rod cap, ‘big end’ 8 Included in connecting rod assembly. 

13 AEG147 NUT,connecting rod cap, ‘big end’ 8 Included in connecting rod assembly. 

14 8G2399STD BEARING SET, connecting rod, 1 Set of 4 pairs , standard size. 


8G2399010 BEARING SET, connecting rod, 1 Set of 4 pairs, 0.010" undersize. 








Crankshaft 



be supplied complete with bearings but other times not,depending on what is available at the time. A 

new forged crankshaft incorporating the most popular combination of Cooper S features (cross-drilled, 

81.33mm stroke for 1275cc, in EN40B material) has been reintroduced in recent years with only minor 

detail differences from the original item and new cranks are also available for 1071 and 970cc engines, 

but machined from billets, not forgings. All three are special orders - please contact us for details. 



For details of the primary gear and its bushes located on the tail of the crankshaft, please see the ‘Manual 

Gearbox - Primary, Idler and Drive Gears’ section in the Transmissions area of the Somerford Mini 

catalogue. 

15 38G343 CRANKSHAFT ASS’Y, with bearings, 1 1071cc. Stamped AEG171. 

EN40B, nitrided, not cross-drilled 

38G357 CRANKSHAFT ASS’Y, with bearings, 1 1275cc, 1964-66. Stamped AEG315 or 

EN40B, nitrided, not cross-drilled AEG316. 


EN40B, nitrided, cross-drilled 

AEG480. 


EN16T, tuftrided, cross-drilled 12G1505. 

28G234 CRANKSHAFT ASS’Y, with bearings, 1 970cc. Stamped AEG330. 



31



32 




16 AEG170 CRANKSHAFT, bare, 1 1071cc . Stamped AEG171. 


AEG315 CRANKSHAFT, bare, 1 1275cc , 1964-66. Stamped AEG315 

EN40B, nitrided, not cross-drilled or AEG316. 


EN40B, nitrided, cross-drilled 

or AEG480. 


EN16T, tuftrided, cross-drilled or 12G1505. 

AEG329 CRANKSHAFT, bare, 1 970cc . Stamped AEG330. 


17 1G1167 RESTRICTOR, oil 1 Included in AEG170, AEG315 and 

AEG329 crankshafts . 

AEG420 RESTRICTOR, oil 1 Included in AEG479 and AEG622 

crankshafts . 

18 8G2391STD BEARING SET, main bearings, 1 Standard size . 


8G2391010 BEARING SET, main bearings, 1 0.010" undersize. 

















21 AEA695 GEAR, steel, timing chain, crankshaft 1 1963-70. 

12G1699 GEAR, iron, timing chain, crankshaft 1 1970-71. 





The 1071, 1275 and 970cc Cooper S engines used two different vibration damper pulleys during their 

production lives. The original design was a separate pulley with a damper screwed to it; eventually a 

one-piece damper pulley was offered as a replacement and was also in fact fitted to all 1969-71 

engines. Both set ups remained available as spares for many years. If you want the original pulley, it is 

still available today from Somerford Mini. 











Three different coupling designs (‘drives’) between the end of the camshaft and the oil pump were used in 

Mini engines, and of course you will need to ensure that if the camshaft or oil pump are replaced that 

the correct matching types are used. Drive methods can be changed in engines (particularly when the 

desired profile of camshaft is not available with the original drive type for your engine), but this tends to 

get a little complicated when sorting out the correct corresponding oil pump to use. Details of which oil 

pumps may be fitted to which engines - and how they can be fitted - are in the Oil Pumps and Oil 

Pressure Relief Valves section of the Somerford Mini Catalogue. 

Up until 1980,all Mini engines - except automatic , 1969-71 Cooper S and 1275 GT units - used pin drive 

camshafts, where a pin across the end of the camshaft engages in a slot in the oil pump shaft (but don’t 

call it slot drive - that’s a different system). 

From 1980 onwards (i.e. from the introduction of A Plus engines) all engines without exception used slot 

drive. In this system the camshaft has a slot in the end which engages with a spade shaped lug on the 

oil pump shaft. Slot drive camshafts are not original for the engines detailed in this section, although 

finding one in a Cooper S engine is not uncommon these days, given the intermittent supply of pin drive 

camshafts and oil pumps. 







Original Cooper S Camshafts 

The standard fitment Cooper S camshafts can be easily distinguished from each other. AEG542 alone is 

designed for a ‘star’ drive oil pump and accepts the necessary drive flange in its end. The other two (‘pin 

drive’) cams can be told apart by AEG510 having a single machined identification ring standing proud 

from the shaft, one lobe up from the distributor gear; AEG148 does not have this ring. AEG542 also has 

a single, but broader, identification ring. All Cooper S camshafts, in common with most other high 

performance A Series camshafts, have 1/2" wide lobes. 

37 AEG148 CAMSHAFT, for ‘pin drive’oil pump 1 1071cc and 970cc . 1275cc 1964-66. 

AEG510 CAMSHAFT, for ‘pin drive’oil pump 1 1275cc 1966-69. 

AEG542 CAMSHAFT, for ‘star drive’ oil pump 1 1275cc 1969-71. 




40 12G4499 SPINDLE, distributor drive 1 

41 2A13 TAPPET, without oil hole 8 1963-68; standard size. 

2A13010 TAPPET, without oil hole 8 1963-68; +0.010" oversize. 

AEG584 TAPPET, with oil hole 8 1968-71; standard size. 

AEG584010 TAPPET, with oil hole 8 1968-71; +0.010" oversize. 

AEG584020 TAPPET, with oil hole 8 1968-71; +0.020" oversize. 

Tappets with or without oil holes are interchangeable, but only in full engine sets. The design with the 

oil hole was introduced in 1968, the intention being to get an improved oil flow around the tappet. 

Undoubtedly it works, but whether the original tappet without the hole suffers from insufficient oil flow, 

even in higher revving fast road or competition engines, is open to debate. Some swear by tappets with 

oil holes, whereas others feel the hole is not required and only serves as an unnecessar y weak point in 

the wall of the tappet. 

42 2A14 PUSH ROD 8 1071cc and 970cc. Alternative to 

12A250 when replaced in sets. 

12A250 PUSH ROD 8 1071cc and 970cc. Alternative to 2A14 

when replaced in sets. 

AEG314 PUSH ROD 8 1275cc . 


34 88G305 PULLEY, crankshaft, with damper 1 

CAM4929 PULLEY, crankshaft, with damper 1 May be used to replace 88G305. 

35 12A283 BOLT, pulley to crankshaft 1 











Timing Chain 

43 2H4905 CHAIN, timing, duplex (double row) 1 

44 AEA696 GEAR, steel, duplex timing chain,camshaft 1 1963-70. 

12G1397 GEAR, iron, duplex timing chain, camshaft 1 1970-71. 

The vast majority of Cooper S engines were fitted with steel timing chain gears on the camshaft and 

crankshaft;only the very last Cooper S Mk IIIs of 1970-71 were fitted with scintered iron gears as used 

on the 1275 GT,Austin 1300 GT, Sprite and Midget, etc. The steel gears are very highly regarded indeed 

and are recommended for any application up to and including race use, being both lighter and more 

resistant to wear than the iron gears. The steel camshaft gear will also tak e further lightening for 

competition use, if desired. That is not to say that the scintered iron gears are poor; they are in fact 

very reliable products which happen to be, unfortunately for them, in the shadow of superb ones. 





33

Cylinder Head - 848 and 997cc 


34 




848 and 997cc Cylinder Head Identification 

Cylinder head details in this section are appropriate for the 848cc engine used in Minis between 1959 

and 1984 and the 997cc engine used in the earliest Mini Coopers built between 1961 and 1963. The 

848cc transverse engine was also to be seen in earlier Mokes and a small number of Austin Metro vans, 

plus in in-line’ form, in an even smaller number of Austin A35 vans. The earliest variant of the Mini 

Cooper was the only BMC/Leyland product ever to receive the 997cc engine. 

The cylinder head design for the 848cc Mini engine is shared with the standard tune Mini 998cc engine, 

but not the 998cc Cooper unit. It was also shared with other BMC model engines, including 803 and 

948cc units to be found in Morris Minors, Austin A30, A35 and A40 models and the ‘Frogeye’ Austin 

Healey Sprite Mk I. Only the castings marked 2A628 (usually earlier models) or 12A1456 (later models) 

are appropriate for Mini - the outwardly similar 2A629 is not. The other obvious distinguishing feature 

of this cylinder head is the inlet valve diameter, which at just 1 1/16" (27mm) is the smallest of any A 

Series head design. 

The 997cc Cooper cylinder head was also fitted to various standard tune 1098cc engines, including the 

single carburetter Austin/Morris 1100 and the 1098cc Minis, plus the high performance 948cc Austin 

Healey Sprite Mk II and MG Midget Mk I. For identification purposes the casting number is 12G202 and 

the inlet valves are 1 5/32" (29.4mm) diameter. 

At various times during A Series engine production, new and reconditioned cylinder heads from the 

factory were either in ‘assembly’ or ‘bare’ condition. Assemblies usually included studs, valves, valve 

springs and guides (but not rockers, rocker shaft and pedestals) whereas bare heads usually included 

valve guides and studs only. These states of build were however not hard and fast,so if you are offered 

a new or reconditioned factory cylinder head on an exchange unit scheme you should establish before 

ordering exactly what you will receive, to guard against the possibility of giving a way components on 

your old head that you will still need in future! 

Rebuilt or Repaired Cylinder Heads 

Somerford Mini Ltd. offers a bespoke cylinder head rebuilding and repair service. In our experience, a 

large number of customers require some degree of modification to their cylinder heads and as a result, 

whether you want a standard head or one that is uprated to any degree, we ask you to contact us to 

discuss your requirements. It would be helpful if you could also supply us with the details of your 

engine: full engine number (if known) and type (capacity, high or low compression, gearbox, breathing 

system, etc.), plus any existing modifications. The more you can provide us with, the better we can help 

you. All of our cylinder heads are built to run on lead-free fuel, unless you specify otherwise. 

1 - CYLINDER HEAD ASS’Y, with valves 1 848cc; please contact us for details . 

(2A628 or 12A1456 casting number) 

- CYLINDER HEAD ASS’Y, with valves 1 997cc; please contact us for details . 

(12G202 casting number) 

2 - CYLINDER HEAD, bare, with guides and 1 848cc; please contact us for details . 

studs only (2A628 or 12A1456 casting ) 

- CYLINDER HEAD, bare, with guides and 1 997cc; please contact us for details . 

studs only (12G202 casting number) 

Gasket Set 

3 GEG101SM GASKET SET, cylinder head 1 See note below. 

The cylinder head gasket set, also known as a ‘decoke’ or ‘decarbonising’ set, includes the cylinder head 

gasket, manifold gasket,two thermostat housing gask ets (one extra to cater for later engines with 

sandwich plates), six HS2 carburetter gaskets, three HS4 carburetter gaskets, rocker cover gasket and 

heater valve gasket. Valve stem oil seals are not included, leaving customers to choose the type and 

quantity they need and order them separately. 

Cylinder Head Components 

Cylinder Head Fixings 

4 GUG2506C GASKET, cylinder head, copper 1 



7 51K1193 NUT, cylinder head to block 9 1959-78 standard fitment. 

8 PWZ106 WASHER, plain 9 1959-78 standard fitment. 

GB126B WASHER, plain 9 Alternative heavy duty washer. 

Withstands up to 80lbf ft torque. 

9 CAM4545 NUT, flanged, cylinder head to block 9 1978 on standard fitment. 

(does not require plain washer) 1959-78 heavy duty alter native. 

Plugs and Adaptors 

10 2K1345 PLUG, oil hole, cylinder head 1 Alternative to 6K808. 

6K808 PLUG, oil hole, cylinder head 1 Alternative to 2K1345. 

11 2A243 ADAPTOR, by-pass hose, short 1 1959-69; use with long by-pass hose. 

12A2075 ADAPTOR, by-pass hose, long 1 1969 on; use with short by-pass hose. 

12 ADP210 PLUG, temperature sender unit boss 1 Models without temperature gauge. 

13 1B3664 WASHER, sealing 1 Models without temperature gauge . 

Thermostat Housing and Fixings 

14 - HOUSING, thermostat 1 

For details of thermostat housings, please see the ‘Cooling - Thermostats and Water Pumps’ section in the 

Cooling and Heating area of the Somerford Mini catalogue. 

15 GTG101 GASKET, thermostat housing, cork 1 

GUG705558 GASKET, thermostat housing, paper 1 

In theory the two gasket materials are interchangeable, but the cork gasket seems to be preferred by 

Somerford Mini customers for a simple thermostat housing fitment, whereas the later paper gasket is 

preferred for a thermostat housing with sandwich plate (not applicable for 848 and 997cc engines). 

16 CHS2515 STUD, thermostat housing 3 

17 FNZ105 NUT 3 


Heater Valve or Tap and Fixings 

19 - VALVE, heater 1 See note below. 

20 - TAP, heater 1 See note below. 

For details of the heater valves and taps, please see the ‘Heating - Heater Hoses, Water Control Valves and 

Cables’ section in the Cooling area of the Somerford Mini catalogue . 

21 2A180 PLATE, blanking heater take-off in 1 For models without heater. 

cylinder head 

22 88G221B GASKET, heater take-off 1 

23 53K402 STUD, heater take-off 2 

24 FNZ104 NUT 2 


Manifold Fixings 

26 GUG704053MG GASKET, manifold 1 

27 53K487 STUD, manifold 6 

Very ear ly 848cc cylinder heads used two each of long, medium and short manifold studs; these were soon 

replaced in production by six of the medium length studs, which can also be fitted to the ear liest engines 

without any necessary modification. 

28 12A1211 WASHER, plain, large, clamping manifold 4 


30 GHF261 NUT,brass , manifold to cylinder head 6 

51K1177 NUT,brass , manifold to cylinder head, long 6 Alternative; easier to access. 

FNZ105 NUT, steel 6 Alternative. 

The steel nut alternative was fitted off and on over the years (most likely as a panic measure when the 

production line ran out of brass nuts) but does tend to seize on the manifold studs unless plenty of 

copper grease is applied. 

Rocker Cover and Fixings 

31 12A475 ROCKER COVER, steel, with breather pipe 1 1959-69 open circuit breathing. 

32 12A1530 ROCKER COVER, steel, no breather pipe 1 1964 on closed circuit breathing. 

33 CAM6822 ROCKER COVER, alloy, no breather pipe 1 Accessory (also MG Metro) item for 

closed circuit breathing models. 

A range of polished or painted alloy accessory rocker covers is available from Somerford Mini; please 

contact us for details. Note that some accessory rocker covers require different fixings from the standard 

items. 

34 - PLATE, engine name 1 See note below. 

- DECAL, engine name 1 See note below. 

- PLATE, engine patent 1 See note below. 

- DECAL, engine patent 1 See note below. 

For details of the large range of plates and decals fixed to rocker covers, please see the ‘Chassis Plates 

and Decals’ section in the Interior Body Fittings area of the Somerford Mini catalogue. 

35 8G612 CAP, oil filler, metal 1 1959-62 open circuit breathing. 

36 12A402 CAP, oil filler, black plastic , without 1 1962-69 open circuit breathing. 

breather Will fit 1959-62 models . 

37 13H2296 CAP, oil filler, black plastic , with breather 1 1964 on closed circuit breathing. 

38 GFE6007 CAP, oil filler, red plastic , with breather 1 For CAM6822 alloy rocker cover. 

39 12A403 SEAL, plastic oil filler cap 1 For 12A402 and 13H2296 caps . 

40 GEG401 GASKET, rocker cover 1 

41 CAM6822FK CHROME FIXINGS KIT, rocker cover 1 

Includes chrome nuts, chrome distance pieces, chrome cup washers and rubber bushes. Originally for alloy 

rocker covers such as CAM6822, may also be used to enhance restored steel rocker covers. 

42 2A150 NUT,rock er cover to engine 2 Original zinc finish. 

CAM6823 NUT,rock er cover to engine 2 Alternative chrome finish. 

43 1B2925 DISTANCE PIECE 2 Original zinc finish. 

12G687 DISTANCE PIECE 2 Alternative chrome finish. 


35



36 




Rocker Cover and Fixings (continued) 

44 1A2156 WASHER, cup 2 Original zinc finish. 

12G679 WASHER, cup 2 Alternative chrome finish. 

45 12A1358 BUSH, rubber 2 

46 12A1968 LIFTING EYE, engine, temporary fitment 2 Fit to engine only while lifting work 

is taking place . 

Rocker Shaft, Rockers and Fixings 

47 12G1926 PEDESTAL, rocker shaft, with oil hole 3 

48 12G1927 PEDESTAL, rocker shaft, with tapped hole 1 

49 2A258 SCREW, locating rocker shaft 1 

50 2A515 PLATE, securing screw 1 1959-74. 

51 2A259 PLATE, securing screw 1 1974 on; will fit 1959-74 models. 

52 51K885 STUD, long, rocker cover and rocker 2 Outer pedestals. 

pedestal 

53 51K1473 STUD, short, rocker pedestal 2 Inner pedestals. 

54 NH605040 NUT, pedestal to cylinder head 4 


56 PWZ105 WASHER, plain 3 1974 on. Not used on tapped 

pedestal. 

57 PWZ106 WASHER, plain 3 1974 on. Not used on tapped 

pedestal. 

58 AEG399 ROCKER SHAFT ASS’Y 1 1959-74. 

59 12A1950 ROCKER SHAFT 1 1974 on; will fit 1959-74 models. 

60 6K878 END PLUG , plain 1 Included in AEG399 rocker shaft ass’y. 

61 2K4608 END PLUG, screwed 1 Included in AEG399 rocker shaft ass’y. 

62 2A964 ROCKER, pressed steel 8 First rocker type. 

63 12G1221 ROCKER, forged 8 Second rocker type. 

64 CAM289 ROCKER, scintered 8 Third rocker type , 1974 on. 

The pressed steel rocker was the first to be fitted, back in 1959. Cooper engines sa w the introduction 

of the stronger forged rocker as a production alternative in the early 1960s, the two types being used in 

standard and high performance engines as alternatives both in production and the parts depar tment until 

1974, when the scintered rocker was introduced. The scintered rocker was used in all engine production 

from that time onwards, although the pressed steel and forged types continued to be offered as 

alternative spare par ts for earlier cars. For normal road use it does not matter which type of rocker is 

used, so long as (i) all eight on the rocker shaft are of the same type; (ii) all eight are either the same 

age from the same engine or are new; and (iii) the tappet adjusting screws and nuts are correct for the 

type of rocker. Note that the forged rockers have replaceable bushes, whereas the other two designs do 

not. 

The pressed steel rocker listed here, 2A964, is the original ‘small bore’ A Series item; the ‘big bore’ 

(1275cc) equivalent listed elsewhere in the Somerford Mini catalogue is 12G1313. The difference in 

theory between the two is a marginal increase in lift with the ‘big bore’ rocker, although in practice this 

is often swallowed up by assembly tolerances. Concerning forged rock ers, again originally there were 

small and big bore engine variants, but since the big bore item is the one available (and it works 

perfectly well on a small bore engine), that’s the one we list here. There were no small or big bore 

variants of the scintered rocker - one type fitted all. 

Several designs of high-lift and roller rockers are also available for tuning purposes, along with special 

valve springs to avoid coil binding, if necessary. Please contact Somerford Mini for details of these and 

other engine tuning parts. 

65 2A21 BUSH, rocker 8 Included in forged rock er. 

66 5C2436 RIVET, bush to rocker 8 Included in forged rock er. 

67 12A1215 SCREW, tappet adjusting 8 Use with pressed steel rocker. 

68 6K654 NUT, locking screw 8 Use with pressed steel rocker. 

69 AEG167 SCREW, tappet adjusting 8 Use with forged rock er. 

70 NT605061 NUT, locking screw 8 Use with forged rock er. 

71 12H3376 SCREW, tappet adjusting 8 Use with scintered rocker. 

72 51K1178 NUT, locking screw 8 Use with scintered rock er. 

73 6K556 SPRING , rock er spacing 3 

74 2A18 WASHER, double coil,outer ends of shaft 2 

75 6K555 WASHER, plain, outer ends of shaft 2 

76 ZPS314 SPLIT PIN , outer ends of shaft 2 

Valve Guides and Valve Seat Inser ts 

77 12G1111 GUIDE, inlet and exhaust valve 8 848cc; standard size. 

12G1111010 GUIDE, inlet and exhaust valve 8 848cc; 0.010" oversize. 

12A186 GUIDE, inlet and exhaust valve 8 997cc; standard size. 

12A186010 GUIDE, inlet and exhaust valve 8 997cc; 0.010" oversize. 

78 2A639 INSERT, inlet valve seat 4 Standard size . 

AEA762 INSERT, inlet valve seat 4 1/16" oversize. 

79 2A640 INSERT, exhaust valve seat 4 Standard size . 

AEA763 INSERT, exhaust valve seat 4 1/16" o versize; for leaded fuel use. 

TAM2068 INSERT, exhaust valve seat 4 Lead free fuel compatible. 

Note that standard size and oversize inserts should not be mixed together on the same cylinder head. 

Valves and Valve Springs 

There are two types of collet used to retain valves in place on these engines and three types of valve to 

take them. The earlier 848cc valve design up to the early 1970s and the 997cc valve design had a 

groove 1/4" deep into which the collets located, whereas later 848cc valves had a groove 1/8" deep, 

either 7/32" from the valve tip or 9/64" from the valve tip (the latter being the 1981 introduced A Plus 

type). Care must be taken to ensure that valves, valve caps , valve springs and collets are matched before 

attempting reassembly. Note also that while the earlier large groove collets were originally secured 

together with circlips, around 1969 these were judged to be adding nothing to the security of the collets 

and were discontinued. 

A range of uprated valves, valve springs and caps to suit most uses are also available from Somerford Mini; 

please contact us for details. 

848cc 1959-74 approx. 

Valves With 1/4" Collet Groove 

80 2A877 VALVE, inlet, 1 1/16" (27mm) dia. 4 

81 AEA434 VALVE, exhaust, 1" (25.4mm) dia. 4 

82 AEA311 SPRING, valve 8 

83 2A11 SPLIT COLLET, pair, valve retaining 8 

84 2A12 CIRCLIP, valve collet 8 1959-69; no longer fitted. 

85 88G616 CAP, upper, valve spring 8 

86 2A879 OIL SEAL, valve stem 8 

87 2A545 SHROUD, valve guide 8 1959-69. 

997cc 1961-63 

Original Valves With 1/4" Collet Groove 

Replacement Valves With 1/4" or 1/8" Collet Groove 

Original 997cc Cooper valves are understandably thin on the ground these days; if difficulty is experienced 

in obtaining originals, AEA574 (1/4" groove) or 12G3036 (1/8" groove) inlet valves and AEA434 (1/4" 

groove) or 12G3035 (1/8" groove) exhaust valves may be used in their place. Take care to use the 

correct collets: 2A11 for 1/4" groove valves, 88G459 collets for 1/8" groove valves. 

88 AEA399 VALVE, inlet, 1 5/32" (29.4mm) dia. 4 Original with 1/4" collet groove. 

AEA574 VALVE, inlet, 1 5/32" (29.4mm) dia. 4 Replacement with 1/4" collet groove. 

12G3036 VALVE, inlet, 1 5/32" (29.4mm) dia. 4 Replacement with 1/8" collet groove. 

89 AEA400 VALVE, exhaust, 1" (25.4mm) dia. 4 Original with 1/4" collet groove. 

AEA434 VALVE, exhaust, 1" (25.4mm) dia. 4 Replacement with 1/4" collet groove. 

12G3035 VALVE, exhaust, 1" (25.4mm) dia. 4 Replacement with 1/8" collet groove. 


91 2A11 SPLIT COLLET, pair, valve retaining 8 Use with original 1/4" groove valves. 

88G459 SPLIT COLLET, pair, valve retaining 8 Use with replacement 1/8" groove 

valves . 

92 2A12 CIRCLIP, valve collet 8 No longer fitted. 



95 2A545 SHROUD, valve guide 8 

848cc 1974 approx. to 1981 

Valves With 1/8" Collet Groove, 7/32" From Valve Tip 

96 CAM6391 VALVE, inlet, 1 1/16" (27mm) dia. 4 

97 12A1987 VALVE, exhaust, 1" (25.4mm) dia. 4 


99 88G459 SPLIT COLLET, pair, valve retaining 8 


101 CAM6520 SHIM, valve spring A/R 

Valve stem oil seals were not listed in factory parts books for this period of 848cc cylinder head 

production. However, it is cer tainly preferable to fit them - part number 2A879 (8 required). The 

CAM6520 shim is a throwback to the late 1970s, when production tolerances were not quite what they 

should have been (!). It is still pretty useful today for obtaining the correct spring fitted length on a 

remachined cylinder head with spring decks that are a bit low. 

848cc 1981 On 

Valves With 1/8" Collet Groove, 9/64" From Valve Tip (A Plus Type) 


103 CAM6503 VALVE, exhaust, 1" (25.4mm) dia. 4 

CAM6505 VALVE, exhaust, 1" (25.4mm) dia., 4 Lead free (chrome stem). 




107 ADU4905 OIL SEAL, inlet valve stem 4 

Originally, 1981 on 848cc engines were fitted with oil seals on the inlet valve stems only, but you can of 

course fit them to all valve stems if desired. Opinions differ on which is better - the choice is yours . 


37



38 




998 and 1098cc Cylinder Head Identification 

Cylinder head parts in this section are for the 998cc engine used in Minis between 1963 and 1992 

(including Elf, Hornet and Cooper models) and the 1098cc engine used between 1975 and 1981. 

The cylinder head design for the standard tune 998cc Mini engine was shared with the 848cc engine, but 

not the 998cc Cooper unit. It was also shared with other BMC model engines , including 803 and 948cc 

units to be found in Morris Minors, Austin A30, A35 and A40 models and the ‘Frogeye’ Austin Healey Sprite 

Mk I. Only the castings marked 2A628 (usually earlier A Series), 12A1456 (later A Series), CAM4005 (air 

injection type) and CAM4180 (A Plus, 1981 on) are appropriate for the standard tune 998cc Mini - the 

outwardly similar 2A629 is not. The other obvious distinguishing feature of this cylinder head is the 

inlet valve diameter, which at just 1 1/16" (27mm) is the smallest of any A Series head design. 

The 998cc Cooper cylinder head was also fitted to high performance 1098cc engines, including the MG , 

Wolsele y, Riley Kestrel and Vanden Plas Princess 1100 models, plus 1098cc Austin Healey Sprites and MG 

Midgets. For identification purposes the casting number is 12G206 (only on the ear liest produced heads) 

or 12G295 (the vast majority), while inlet valves are 5/32" larger than standard 998cc items at 1 7/32" 

(31mm) diameter. For flow characteristics the number 12G295 is writ large in Mini tuners’ folklore. It 

is wholeheartedly recommended for uprated small bore A Series engines other than for full race. 

The Mini 1098cc cylinder head design also saw use on several other engines including the Austin/Morris 

1100, the 948cc Austin Healey Sprite Mk II/MG Midget Mk I and the 997cc Mini Cooper. For 

identification purposes the casting number is 12G202 and inlet valves are 1 5/32" (29.4mm) diameter. 

At various times during engine production, new and reconditioned cylinder heads from the factory were 

either in ‘assembly’ or ‘bare’ condition. Assemblies usually included studs, valves, valve springs and guides 

(but not rockers, rocker shaft and pedestals); bare heads usually included valve guides and studs only. 

These states of build were not hard and fast, so if you are offered a new or reconditioned factory 

cylinder head on an exchange unit scheme you should establish what you will receive before ordering, to 

guard against the possibility of giving away parts on your old head that you will still need in future. 









1 - CYLINDER HEAD ASS’Y, with valves 1 998cc 1963-80 (not Cooper); please 

(2A628 or 12A1456 casting number) contact us for details. 

- CYLINDER HEAD ASS’Y, with valves 1 998cc 1975-80 (Canada and Sweden); 

(12A1456 or CAM4005 casting, with please contact us for details . 

air ports) 

- CYLINDER HEAD ASS’Y, with valves 1 998cc 1981 on (A Plus); please 

(CAM4180 casting number) 

contact us for details. 

- CYLINDER HEAD ASS’Y, with valves 1 998cc (Cooper); please contact us for 

(12G206 or 12G295 casting number) details. 

- CYLINDER HEAD ASS’Y, with valves 1 1098cc; please contact us for details . 

(12G202 casting number) 

2 - CYLINDER HEAD, bare, with guides and 1 998cc 1963-80 (not Cooper); please 

studs only (2A628 or 12A1456 casting) contact us for details. 

- CYLINDER HEAD, bare, with guides and 1 998cc 1975-80 (Canada and Sweden); 

studs only (12A1456 or CAM4005 casting, please contact us for details . 

with air por ts) 

- CYLINDER HEAD, bare, with guides and 1 998cc 1981 on (A Plus); please 

studs only (CAM4180 casting) 


- CYLINDER HEAD, bare, with guides and 1 998cc (Cooper); please contact us for 

studs only (12G206 or 12G295 casting) details. 

- CYLINDER HEAD, bare, with guides and 1 1098cc; please contact us for details . 

studs only (12G202 casting ) 

Gasket Set 

3 GEG101SM GASKET SET, cylinder head 1 See note below. 

The cylinder head gasket set, also known as a ‘decoke’ or ‘decarbonising’ set, includes the head gasket, 

manifold gasket, two thermostat housing gaskets (one extra for engines with sandwich plates), six HS2 

carburetter gaskets, three HS4 carburetter gaskets, rocker cover gasket and heater valve gasket. Valve 

stem oil seals are not included; please choose the type and quantity required and order them separately. 



4 GUG2506C GASKET, cylinder head, copper 1 








(does not require plain washer) 1963-78 heavy duty alter native. 


10 2K1345 PLUG, oil hole, cylinder head 1 1963-85; alternative to 6K808. 

6K808 PLUG, oil hole, cylinder head 1 1963-85; alternative to 2K1345. 

RU612123 RIVET, oil hole, cylinder head 1 1985 on. 

11 2A243 ADAPTOR, by-pass hose, shor t 1 1963-69; use with long by-pass hose. 

12A2075 ADAPTOR, by-pass hose, long 1 1969 on; use with short by-pass hose. 

12 12G1454 TUBE, air injection port 4 Canada and Sweden 1975-80. 

13 ADP210 PLUG, temperature sender unit boss 1 Models without temperature gauge. 

14 1B3664 WASHER, sealing 1 Models without temperature gauge. 





16 GTG101 GASKET, thermostat housing, cork 1/2 Qty. 2 required for Japan 1980 on. 

GUG705558 GASKET, thermostat housing, paper 1/2 Qty. 2 required for Japan 1980 on. 



preferred for a thermostat housing with sandwich plate (applicable for Japan 1980 on). 


FHS2518 STUD, thermostat housing 3 Canada and Sweden 1975-80. 

CHS2524 STUD, thermostat housing/sandwich plate 3 Japan 1980 on. 

18 FNZ105 NUT 3 


Heater Valve or Tap and Fixings 1963-88 


21 - TAP, heater 1 See note below. 

For details of the heater valves and taps, please see the ‘Heating - Heater Hoses, Water Control Valves and 

Cables’ section in the Cooling area of the Somerford Mini catalogue . 

22 2A180 PLATE, blanking heater take-off in head 1 For models without heater. 

23 88G221B GASKET, heater take-off 1 

24 53K402 STUD, heater take-off 2 

25 FNZ104 NUT 2 


Heater Adaptor and Fixings 1988 On 

27 12G2534 ADAPTOR, heater, cylinder head 1 

28 88G221B GASKET, adaptor to cylinder head 1 

29 TAM1368 SCREW, adaptor to cylinder head 2 


30 GUG704053MG GASKET, manifold 1 




34 GHF261 NUT,brass , manifold to cylinder head 6 

51K1177 NUT,brass , manifold to cylinder head, long 6 Alternative; easier to access. 


The steel nut was fitted off and on over the years (most likely as a panic measure when the production 

line ran out of brass nuts) but does tend to seize on manifold studs unless copper grease is applied. 


35 12A475 ROCKER COVER, steel, with breather pipe 1 1963-69 open circuit breathing models. 

36 12A1530 ROCKER COVER, steel, without breather pipe1 1964 on closed circuit breathing models. 

CAM4543 ROCKER COVER, steel, with breather pipe 1 Canada and Sweden 1975-80. 

37 CAM6822 ROCKER COVER, alloy, without breather pipe1 Accessory (also MG Metro) item for 



contact us for details. Note some accessory rocker covers require different fixings from the standard items. 

38 - PLATE, engine name 1 See note on next page. 

- DECAL, engine name 1 See note on next page. 


- DECAL, engine patent 1 See note below. 


and Decals’ section in the Interior Body Fittings area of the Somerford Mini catalo gue. 

39 12A402 CAP, oil filler, black plastic, without breather 1 1963-69 open circuit breathing models. 

40 13H2296 CAP, oil filler, black plastic , with breather 1 1964 on closed circuit breathing models. 

41 GFE6007 CAP, oil filler, red plastic , with breather 1 For CAM6822 alloy rocker cover. 

42 12A403 SEAL, plastic oil filler cap 1 For 12A402 and 13H2296 caps . 



Includes chrome nuts, chrome distance pieces, chrome cup washers and rubber bushes. Originally for alloy 

rocker covers such as CAM6822, may also be used to enhance restored steel rocker covers. 


39



40 




Rocker Cover and Fixings (continued) 

45 2A150 NUT, rocker cover to engine 2 Original zinc finish. 

CAM6823 NUT, rocker cover to engine 2 Alternative chrome finish. 






49 12A1968 LIFTING EYE, engine, temporary fitment 2 Fit only while lifting work is taking place. 







55 51K885 STUD, long, rocker cover and pedestal 2 Outer pedestals. 

56 51K1473 STUD, short, rocker pedestal 2 998cc , inner pedestals. 

CHS522 STUD, short, rocker pedestal 2 1098cc , inner pedestals. 

57 FNZ105 NUT, pedestal to cylinder head 4 


59 PWZ105 WASHER, plain 3 1969 on. Not on tapped pedestal. 

60 PWZ106 WASHER, plain 3 1969 on. Not on tapped pedestal. 





65 2A964 ROCKER, pressed steel 8 First rocker type. 


67 CAM289 ROCKER, scintered 8 Third rocker type , 1974 on. 

Pressed steel rockers and the stronger forged rockers were used in standard and high performance 

engines as alternatives both in production and the parts department until 1974, from which point the 

scintered rocker was used in all engine production. The pressed steel and forged types continued to be 

offered as alternative spare parts for earlier cars. For normal road use it does not matter which type is 

used, so long as (i) all eight on the rocker shaft are of the same type; (ii) all eight are either the same 

age from the same engine or are new; and (iii) the tappet adjusting screws and nuts are correct for the 

type of rocker. Note that forged rock ers have replaceable bushes, the other two designs do not. 

1970s to 1980) or 9/64" from the valve tip (the 1981 introduced A Plus type). There then came the 

last variation, from 1984 onwards, where the collet located into an easily recognised triple groove on the 

valve. Care must be taken to ensure that valves, valve caps , valve springs and collets are matched before 

attempting reassembly. Note also that while early large groove collets were originally secured with circlips, 

around 1969 these were judged to be adding nothing to the security of the collets and were discontinued. 

A range of uprated valves, valve springs and caps to suit most uses are also available from Somerford Mini; 

please contact us for details. 

998cc (Not Cooper) 1963-74 approx 


83 2A877 VALVE, inlet, 1 1/16" (27mm) dia. 4 

84 AEA434 VALVE, exhaust, 1" (25.4mm) dia. 4 


86 2A11 SPLIT COLLET, pair, valve retaining 8 




90 2A545 SHROUD, valve guide 8 1963-69. 

998cc (Cooper) 1963-69 

Original Valves With 1/4" Collet Groove 

Replacement Valves With 1/8" Collet Groove 

Note that in the event of the original AEA400 exhaust valve not being available, the standard tune 998cc 

exhaust valve AEA434 may be substituted. Other replacement valves include 12G3034 and 12G3035 but 

since these have 1/8" collet grooves, 88G459 collets must be fitted with them. 

91 12G296 VALVE, inlet, 1 7/32" (31mm) dia. 4 Original with 1/4" collet groove. 

12G3034 VALVE, inlet, 1 7/32" (31mm) dia. 4 Replacement with 1/8" collet groove. 

92 AEA400 VALVE, exhaust, 1" (25.4mm) dia. 4 Original with 1/4" collet groove. 

AEA434 VALVE, exhaust, 1" (25.4mm) dia. 4 Replacement with 1/4" collet groove. 

12G3035 VALVE, exhaust, 1" (25.4mm) dia. 4 Replacement with 1/8" collet groove. 

93 AEA311 SPRING, valve, outer 8 

94 AEA401 SPRING, valve, inner 8 

95 2A11 SPLIT COLLET, pair, valve retaining 8 Use with original 1/4" groove valves. 

88G459 SPLIT COLLET, pair, valve retaining 8 Use with replacement 1/8" groove valves. 


97 88G616 CAP, upper, valve springs 8 

98 AEA403 COLLAR, lower, valve springs 8 


The pressed steel rocker listed here, 2A964, is the original ‘small bore’ A Series item; the ‘big bore’ 

(1275cc) equivalent listed elsewhere in the Somerford catalogue is 12G1313. The difference between the 

two is a mar ginal increase in lift with the ‘big bore’ rocker, although in practice this is often swallowed 

up by assembly tolerances. Similarly, originally there were small and big bore for ged rockers, but since 

the big bore item is the one available (and it works perfectly well on a small bore engine), that’s the 

one we’ve listed. There were no small or big bore variants of the scintered rocker - one type fitted all. 

Several designs of high-lift and roller rockers for tuning are available, with special valve springs to avoid 

coil binding if required. Please contact Somerford Mini for details of our range of engine tuning parts. 

998cc 1974 approx. to 1981 







105 2A879 OIL SEAL, valve stem 8 Not originally specified - fit if desired. 

106 CAM6520 SHIM, valve spring A/R 

68 2A21 BUSH, rocker 8 Included in forged rock er. 

69 5C2436 RIVET, bush to rocker 8 Included in forged rock er. 



72 AEG167 SCREW, tappet adjusting 8 Use with forged rock er. 

73 NT605061 NUT, locking screw 8 Use with forged rock er. 


75 51K1178 NUT, locking screw 8 Use with scintered rock er. 

76 6K556 SPRING , rock er spacing 3 

77 2A18 WASHER, double coil,outer ends of shaft 2 


79 ZPS314 SPLIT PIN , outer ends of shaft 2 

Valve Guides and Valve Seat Inser ts 

80 12G1111 GUIDE, inlet and exhaust valve 8 998cc , not Cooper ; standard size. 

12G1111010 GUIDE, inlet and exhaust valve 8 998cc , not Cooper; 0.010" oversize. 

12A186 GUIDE, inlet and exhaust valve 8 998cc Cooper/1098cc; standard size. 

12A186010 GUIDE, inlet and exhaust valve 8 998cc Cooper/1098cc; 0.010" oversize. 

81 2A639 INSERT, inlet valve seat 4 998cc standard size . 

AEA762 INSERT, inlet valve seat 4 998cc 1/16" oversize. 

12A392 INSERT, inlet valve seat 4 1098cc . 

TAM2152 INSERT, inlet valve seat 4 Lead free fuel compatible. 

82 2A640 INSERT, exhaust valve seat 4 Standard size . 

AEA763 INSERT, exhaust valve seat 4 1/16" o versize; for leaded fuel use. 

TAM2068 INSERT, exhaust valve seat 4 Lead free fuel compatible . 

Note that standard size and oversize inser ts should not be mixed together on the same cylinder head. 


There are three types of collet used to retain valves in place on these engines and four types of valve 

to take them. The earlier valve designs up to the ear ly 1970s had a groove 1/4" deep into which the 

collets located, whereas later valves had a groove 1/8" deep, either 7/32" from the valve tip (early 

1098cc 1975-81 


107 12G3036 VALVE, inlet, 1 5/32" (29.4mm) dia. 4 


109 12G4287 SPRING, valve 8 



112 2A879 OIL SEAL, valve stem 8 Not originally specified - fit if desired. 

998cc 1981-84 

Valves With 1/8" Collet Groove, 9/64" From Valve Tip (A Plus Type) 


114 CAM6503 VALVE, exhaust, 1" (25.4mm) dia. 4 

CAM6505 VALVE, exhaust, 1" (25.4mm) dia., 4 Lead free fuel (chrome stem). 

115 12G1015 SPRING, valve 8 High (10.3:1) comp. ratio engines. 

AEA311 SPRING, valve 8 Low (8.3:1) comp. ratio engines. 



118 ADU4905 OIL SEAL, valve stem 4/8 

For a period, engines were fitted with oil seals on the inlet valve stems only, after which all valves wore 

them. Opinions differ on which is better - the choice is yours. 

998cc 1984 On 

Valves With Triple Collet Groove (A Plus Type) 

119 TAM1062 VALVE, inlet, 1 1/16" (27mm) dia. 4 Lead free fuel compatible. 

120 TAM1770 VALVE, exhaust, 1" (25.4mm) dia. 4 Lead free fuel compatible. 

121 12G1015 SPRING, valve 8 High (10.3:1) comp. ratio engines. 

AEA311 SPRING, valve 8 Low (8.3:1) comp. ratio engines. 

122 CAM6975 SPLIT COLLET, pair, valve retaining 8 

123 AHU1897 CAP, upper, valve spring 8 

124 ADU4905 OIL SEAL, valve stem 8 


41

Cylinder Head - 1275cc (Not Cooper S) 


42 




1275cc Cylinder Head Identification 

Cylinder head details here are appropriate for the 1275cc engine in Mini 1275 GTs from 1969 to 1980, 

Mini Coopers from 1990 onwards and standard Minis from 1992 on. The ‘eleven stud’ heads for 1275cc 

Mini Cooper S engines are described in the next section of the Somerford Mini catalogue. 

The cylinder head design for the non-Cooper S 1275cc Mini engine was shared with many other BMC/ 

Leyland/Austin Rover model engines, but unlike other A Series cylinder heads it was only ever fitted to 

the one size of engine. Thus other cars sharing the cylinder head were all 1275cc models, including the 

Austin/Morris 1300 (but not the high performance versions, which used the late Cooper S head), Morris 

Marina and Ital 1.3, Austin Allegro 1300 and 1.3, Austin Healey Sprite Mk IV/MG Midget Mk III, Austin/MG 

Metro, Austin Maestro and Montego. The number cast into the cylinder head is 12G940, but note that 

there are several versions of cylinder head identified by this number, which means that care has to be 

taken when sourcing a head to use on your Mini. 

- CYLINDER HEAD, bare, with guides only 1 1275cc carburetter 1992-94; please 

(late 12G940 casting) 


- CYLINDER HEAD, bare, with guides only 1 Multi and single point injection 1997 


on; please contact us for details. 

Gasket Set 

3 GEG103SMC GASKET SET, cylinder head 1 Carburetter models 1969-94. 

GEG103SMI GASKET SET, cylinder head 1 Single and multi point injection 1991 on. 

The cylinder head gasket set,also kno wn as a ‘decoke’ or ‘decarbonising’ set, includes the head gask et, 

manifold gasket (standard in the carburetter gasket set, reinforced in the injection set), two thermostat 

housing gaskets (one extra for engines with sandwich plates), HS2, HS4 and HIF carburetter gaskets 

(carburetter gasket set only), rocker cover gasket, plus heater take-off gasket (carburetter gasket set only). 

Valve stem oil seals are not included; please choose the ones you want and order them separately. 

Different versions of 12G940 heads used either 1 5/16" (33mm) or 1 13/32" (35.6mm) inlet valves; 1 

5/16" is the correct diameter for an inlet valve in an original non-Cooper S Mini engine (exhaust valves 

are always 1 5/32" (29.4mm) diameter, whatever the application). Cooper S, high performance Austin/ 

Morris 1300 and MG Metro models somehow squeezed in the larger 1 13/32" diameter inlet valves. 

Confusingly, the last Cooper S cylinder heads plus the aforementioned high performance 1300 heads are 

still 12G940 castings, even though they have ‘eleven stud’ fixings to the cylinder block (standard 12G940s 

are nine stud); they do however have an extra 12G1805 part number stamped by the thermostat housing 

for extra identification. As mentioned above, these later Cooper S heads are detailed in the next section. 

Late model 12G940 castings, used on 1990s Minis, can be distinguished by separate sculpted and 

machined areas around the thermostat housing and heater take off, whereas the ear lier castings are 

machined straight across from these areas to the rocker cover. Once again, care needs to be taken here: 

do not assume that if you have identified a late casting it must be Mini specification. Metros also used 

this casting with the heater take-off blank ed off (as was the take-off on fuel injection and 1992-94 

carburetter Mini heads), and the MGs had the larger 1 13/32" inlet valves. Metro Turbos and ERA Mini 

Turbos similarly used late type 12G940 heads, this time with Mini sized inlet valves - the valves are 

however sodium filled and the deck of the cylinder head is thinner. 

Lastly, mention should be made of the air injection cylinder head used on North American specification 

(NAS) Austin Healey Sprite Mk IVs, MG Midget Mk IIIs and Austin Americas between 1968 and 1974. This 

head casting, displaying part number 12G939, is a strengthened version of the 12G940 including air 

injection ports for the NAS emission control systems. While on the face of it not strictly relevant to a 

Mini parts catalogue, it is in all other respects a 12G940 head and because of its increased strength it 

makes an ideal and reliable candidate for tuning treatment. Plenty of new 12G939 heads were still 

around in the classic car par ts marketplace at the beginning of the 1990s and while it will not be easy, 

you can find one even now if you want one. 



springs and guides (but not rockers, rocker shaft and pedestals) whereas bare heads included valve guides 

and studs or valve guides only. These states of build were however not hard and fast, so if you are 

offered a new or reconditioned factory cylinder head on an exchange unit scheme you should establish 

before ordering exactly what you will receive, to guard against the possibility of giving a way components 

on your old head that you will still need in future! 











4 GEG300 GASKET, cylinder head, copper 1 


6 CAM151 STUD, cylinder head, short 5/4 Qty. reduced 1990-96. 

TAM1617 STUD, cylinder head and coil bracket 1 1990-96. 






(does not require plain washer) 1969-78 heavy duty alternative. 

CAM4545 NUT,flanged, coil bracket to head stud 1 1990-96. 


10 2K1345 PLUG, oil hole, cylinder head 1 1969-80, alternative. 

6K808 PLUG, oil hole, cylinder head 1 1969-80, alternative. 

11 CDU2601 RIVET, oil hole, cylinder head 1 1990-96. 

LYQ100050 RIVET, oil hole, cylinder head 1 1997 on. 

12 12G2092 PLUG, water hole 3 1969-96. 

154545A PLUG, water hole 3 1997 on. 

13 AEA771 PLUG, water and dowel hole 2 

14 12G3503 PLUG, cleaning hole 2 1969-96. 

15 12A2075 ADAPTOR, by-pass hose, long 1 1969-80 and 1275cc carburetter 

models 1992-94. 





17 GTG101 GASKET, thermostat housing, cork 1/2 Qty. 2 required 1990 on. 

GUG705558 GASKET, thermostat housing, paper 1/2 Qty. 2 required 1990 on. 



preferred for a thermostat housing with sandwich plate (applicable for 1990 on). 

18 CHS2515 STUD, thermostat housing 3 1969-80 (carburetter models). 

CHS2524 STUD, thermostat housing/sandwich plate 3 1990-91 (carburetter models). 

19 FNZ105 NUT 3 1969-91 (carburetter models). 

20 PWZ105 WASHER, plain 3 1969-91 (carburetter models). 

21 DAM7760 BOLT, thermostat housing/sandwich plate 3 1991 on (injection and 1992-94 

carburetter models). 

1 - CYLINDER HEAD ASS’Y, with valves 1 1275 GT 1969-80; please contact us 

(early 12G940 casting) 

for details. 

- CYLINDER HEAD ASS’Y, with valves 1 Cooper carburetter 1990-91; please 



- CYLINDER HEAD ASS’Y, with valves 1 Single point injection 1991-96; please 



- CYLINDER HEAD ASS’Y, with valves 1 1275cc carburetter 1992-94; please 



- CYLINDER HEAD ASS’Y, with valves 1 Multi and single point injection 1997 


on; please contact us for details. 

2 - CYLINDER HEAD, bare, with guides and 1 1275 GT 1969-80; please contact us 

studs only (ear ly 12G940 casting) for details. 

- CYLINDER HEAD, bare, with guides only 1 Cooper carburetter 1990-91; please 



- CYLINDER HEAD, bare, with guides only 1 Single point injection 1991-96; please 



Heater Valve and Fixings 

1275 GT 1969-80 


For details of the heater valves, please see the ‘Heating - Heater Hoses, Water Control Valves and Cables’ 

section in the Cooling area of the Somerford Mini catalogue. 

23 88G221B GASKET, heater valve 1 

24 53K402 STUD, heater valve 2 

25 FNZ104 NUT 2 


Heated Manifold Adaptor and Fixings 

Cooper Carburetter 1990-91 

27 12G2534 ADAPTOR, heated manifold take-off 1 

28 88G221B GASKET, adaptor to cylinder head 1 

29 TAM1368 SCREW, adaptor to cylinder head 2 


43



44 




Combined Inlet and Exhaust Manifold Fixings 

1275 GT 1969-80 and 1275cc Carburetter Models 1992-94 

30 GUG704053MG GASKET, manifold, standard 1 

31 53K487 STUD, manifold 6 1969-80. 

LYR10028 STUD, manifold 6 1992-94. 



34 GHF261 NUT, brass, manifold to cylinder head 6 

51K1177 NUT, brass, manifold to cylinder head,long 6 Alternative; easier to access . 


Separate Inlet and Exhaust Manifold Fixings 

Cooper Carburetter 1990-91 




38 GHF261 NUT, brass, manifolds to cylinder head 6 

Separate Inlet and Exhaust Manifold Fixings 

Injection Models 1991 On 

39 GUG704063MG GASKET, manifold, reinforced 1 

40 LYR10028 STUD, manifold 6 1991-96 single point injection. 

53K487 STUD, manifold, outer 2 1997 on multi and single point injection. 

LYR10028 STUD, manifold, inner 4 1997 on multi and single point injection. 


42 GHF261 NUT, brass, manifolds to head 2 

43 LYH10008 NUT AND WASHER,manifolds to head 4 


44 12A1530 ROCKER COVER, steel, black 1 1969-80. 

LDR10074 ROCKER COVER, steel, black 1 1990 on. 

LDR103490 ROCKER COVER, steel, citrus green 1 1998 P aul Smith limited edition. 

45 CAM6822 ROCKER COVER, alloy 1 Accessory (also MG Metro) item. 


contact us for details. Some accessory rocker covers require different fixings from the standard items. 

46 - DECAL, rocker cover 1 See note belo w. 



47 13H2296 CAP, oil filler, black plastic, with breather 1 

48 GFE6007 CAP, oil filler, red plastic, with breather 1 For CAM6822 alloy rocker cover. 

49 12A403 SEAL, plastic oil filler cap 1 For 13H2296 cap. 



Includes chrome nuts, chrome distance pieces, chrome cup washers and rubber bushes. Originally for 

alloy rocker covers such as CAM6822,may also be used to enhance restored steel rocker covers. 








56 12H2557 NUT, extension, air intake to rocker cover 2 1990-91 carburetter models . 

57 12A1968 LIFTING EYE, engine, temporary fitment 2 Fit only while lifting work is taking place. 








64 CHS522 STUD, short, rocker pedestal 2 Inner pedestals. 

65 LNZ205 NUT, nyloc, pedestal to cylinder head 4 1969-80. 

66 PWZ105 WASHER, plain (not on tapped pedestal) 3 1969-80. 

67 PWZ106 WASHER, plain (not on tapped pedestal) 3 1969-80. 

68 NH605040 NUT, pedestal to cylinder head 4 1990 on. 

69 PWZ105 WASHER, plain (not on tapped pedestal) 3 1990 on. 





74 12G1313 ROCKER, pressed steel 8 First rocker type. 


76 CAM289 ROCKER, scintered 8 Third rocker type, 1974 on. 

Pressed steel rockers and the stronger for ged rockers were used in standard and high performance engines 

as alternatives both in production and the parts department until 1974, when the scintered rocker was 

introduced. The scintered rocker was used in all engine production from that time onwards, although the 

pressed steel and forged types continued to be offered as alternative spare par ts for earlier cars. For 

normal road use it does not matter which type of rocker is used,so long as (i) all eight on the rocker 

shaft are of the same type; (ii) all eight are either the same age from the same engine or are new; and 

(iii) the tappet adjusting screws and nuts, plus the rocker spacing washers, are correct for the type of 

rocker. Note that the forged rock ers have replaceable bushes, whereas the other two designs do not. 

Several designs of high-lift and roller rockers are available for tuning purposes, along with special valve 

springs to avoid coil binding. Please contact Somerford Mini for details of these and other tuning par ts. 

77 2A21 BUSH, rock er 8 Included in forged rocker. 

78 5C2436 RIVET, bush to rocker 8 Included in forged rocker. 



81 AEG167 SCREW, tappet adjusting 8 Use with forged rocker. 

82 NT605061 NUT, locking screw 8 Use with forged rocker. 


84 51K1178 NUT, locking screw 8 Use with scintered rocker. 

85 6K556 SPRING, rocker spacing 3 

86 AEG168 DISTANCE PIECE, exhaust rock er 6 For pressed steel and forged rock ers. 

87 2A18 WASHER, double coil, outer ends of shaft 2 For scintered rockers. 

The distance piece AEG168 is used to position forged rock ers correctly over the exhaust valves. It is only 

required on big bore (970, 1071 and 1275cc) cylinder heads, where the valves are spaced further apart 

than on other A Series engines. The wider scintered rockers do not require distance pieces, so instead use 

the more usual A Series set up of double coil (or ‘Thackery’) washers at either end of the rocker shaft. 


89 ZPS314 SPLIT PIN, outer ends of shaft 2 

Valve Guides and Valve Seat Inserts 

90 12G1111 GUIDE, inlet and exhaust valve 8 Standard size . 

12G1111010 GUIDE, inlet and exhaust valve 8 0.010" oversize. 

91 12G1089 INSERT, inlet valve seat 4 1969-80, not lead free fuel compatible. 

92 12G1090 INSERT, exhaust valve seat 4 1969-80, not lead free fuel compatible. 

TAM2069 INSERT, exhaust valve seat 4 1990 on, lead free fuel compatible . 


Valves are a lot more simple on the Mini 1275cc cylinder head than on other A Series heads. There are 

two types, identifiable by the collet grooves on the valve stems. The 1969-80 design of valve has a 

single collet groove 1/4" deep, whereas the later (lead free) valve design fitted in the 1990s has a 

distinctive triple groove. Care must be taken to ensure that valves, valve caps and collets are matched 

before attempting reassembly. The later triple groove valves, caps and collets may be used on ear lier 

cylinder heads along with TAM2069 exhaust valve seat inserts as a lead free conversion. Austin and MG 

Metro components are also detailed here for the benefit of the many, many Mini owners who have 

transplanted Metro power units into their cars. A range of uprated valves, valve springs and caps to suit 

most uses are also available from Somerford Mini; please contact us for details. 

1969-80 (original pre-A Plus Mini engines) 

1980-84 (early A Plus Austin and MG Metro engines) 


93 12G941 VALVE, inlet, 1 5/16" (33mm) dia. 4 Mini and Austin Metro engines . 

AEG592 VALVE, inlet, 1 13/32" (35.6mm) dia. 4 MG Metro engines. 

94 CAM4601 VALVE, exhaust, 1 5/32" (29.4mm) dia. 4 




98 AEG327 OIL SEAL, valve stem 4/8 

Oil seals were usually fitted on the inlet valve stems only, but they can be fitted on exhaust valves too. 

Opinions differ on which is better - the choice is yours. 

1990 On (original A Plus Mini engines) 

1984-90 (later A Plus Austin and MG Metro engines) 

Valves With Triple Collet Groove 

99 TAM1058 VALVE, inlet, 1 5/16" (33mm) dia. 4 Lead free; Mini and Austin Metro engines. 

TAM1059 VALVE, inlet, 1 13/32" (35.6mm) dia. 4 Lead free; MG Metro engines. 

100 TAM1061 VALVE, exhaust, 1 5/32" (29.4mm) dia. 4 Lead free fuel compatible. 


102 CAM6975 SPLIT COLLET, pair, valve retaining 8 

103 AHU1897 CAP, upper, valve spring 8 

104 ADU4905 OIL SEAL, valve stem 8 


45

Cylinder Head - 970, 1071 and 1275cc (Cooper S) 


46 




970, 1071 and 1275cc Cooper S 

Cylinder Head Identification 

Cylinder head details in this section are appropriate for all variants of Cooper S engine, built between 

1963 and 1971. Three cylinder head designs were used, identifiable by casting numbers 12A185, AEG163 

and 12G940. All three will fit any capacity Cooper S engine and all three are interchangeable as 

complete assemblies. This does not, ho wever, mean that all components can be easily swapped between 

them. 

All Cooper S cylinder heads are referred to as ‘eleven stud’ heads because of the attachment method to 

the cylinder block (actually inaccurate since ten studs and a bolt are used); all other Mini cylinder heads 

are attached with nine studs. The two extra fixings are clearly visible at either end of the rocker cover, 

the gasket flange of which is notched to accept them. The only other BMC/Leyland engine to be fitted 

with an eleven stud cylinder head was that to be found in the high performance derivatives of the 

Austin/Morris 1300 (1300 GT, MG 1300 etc .) and the Italian-built Innocenti Mini Cooper 1300,and 

indeed the cylinder head fitted was the 1969-71 Cooper S item. This does not mean however that the 

1300 GT engine is a Cooper S engine, since there are many other differences between them, including 

the engine block itself, but it still makes a very desirable power unit to transplant into a Mini. 

The first Cooper S cylinder head, introduced on the 1071cc model in 1963, was marked with the casting 

number 12A185 and additionally may be identified by a yellow colour coding. The valves fitted are 

distinctly larger than those in the cylinder heads of non-Cooper S Minis - the inlet valve is 1 13/32" 

(35.6mm) in diameter and the exhaust valve is 1 7/32" (31mm) in diameter. Additionally, the valves 

are uniquely manufactured in Nimonic 80 (EN214N) steel and use double valve springs. 

Towards the end of 1963 a new cylinder head casting was introduced, marked with the part number 

AEG163 and colour coded blue or brown. The only difference between the 12A185 and AEG163 castings 

is a production modification in the internal oil ways in the later casting; it affects neither performance 

nor reliability of the head. The valves , valve springs and rocker gear all continued unchanged from the 

12A185 head. The AEG163 cylinder head was fitted from late 1963 through to 1969 and thus saw use 

on the last 1071cc engines, all 970cc engines and all but the last 15 months or so of 1275cc engine 

production. 

The 12G940 cylinder head casting was officially introduced on the 1275cc Cooper S engine at the 

beginning of Mini Mk III production, for the 1970 model year. Alongside the casting number in the 

centre of the top face of the head, the other identifying mark is the part number 12G1805 stamped by 

the thermostat housing. It may well also have been fitted to the last few Cooper S Mk IIs; this is 

difficult to prove, not least because the factory parts and service department soon offered the 12G940 

head as the only replacement for all Cooper S heads, meaning that a significant number of 1960s cars 

are now fitted with them. Using the eleven stud 12G940 head on the Cooper S saved manufacturing 

costs through component sharing with other models (the aforementioned Austin/Morris 1300 and 

Innocenti). 

It also improved Cooper S cylinder head reliability, for a small cost in performance , since smaller exhaust 

valves in the 12G940 head allowed for more material to be left between the inlet and exhaust valves; 

this area was prone to cracking on the 12A185 and AEG163 heads . The inlet valve size on the 12G940 

is, as previously, 1 13/32" (35.6mm) diameter, but the exhaust valve size is reduced by 1/16" to 1 5/ 

32"(29.4mm) diameter. The valves are made from standard, not Nimonic , material and ha ve longer 

stems to compensate for the higher valve spring seat on the 12G940 casting. Thus even the inlet valves 

are not directly interchangeable with earlier Cooper S items, though their diameter is the same. 

The nine stud fixing 12G940 cylinder heads used on other 1275cc BMC/Leyland/Austin Rover engines are 

not, of course, capable of being fitted to a Cooper S engine without very costly modification - they 

usually have smaller valves than the eleven stud 12G940 (MG Metro etc . excepted) an yway. 



springs and guides (but not rockers, rocker shaft and pedestals) whereas bare heads included valve guides 

and studs or valve guides only. These states of build were however not hard and fast, so if you are 

offered a new or reconditioned factory cylinder head on an exchange unit scheme you should establish 

before ordering exactly what you will receive, to guard against the possibility of giving a way components 

on your old head that you will still need in future! 









1 - CYLINDER HEAD ASS’Y, with valves 1 970, 1071 and 1275cc 1963-69. 

(12A185 or AEG163 casting) 

- CYLINDER HEAD ASS’Y, with valves 1 1275cc 1969-71. 

(12G940 casting) 

2 - CYLINDER HEAD, bare, with guides and 1 970, 1071 and 1275cc 1963-69. 

studs only (12A185 or AEG163 casting) 

- CYLINDER HEAD, bare, with guides and 1 1275cc 1969-71. 

studs only (12G940 casting) 

Gasket Set 

3 GEG103SMC GASKET SET, cylinder head 1 

The cylinder head gasket set, also known as a ‘decoke’ or ‘decarbonising’ set, includes the cylinder head 

gasket, manifold gasket, two thermostat housing gaskets (one extra to cater for other 1275cc Mini engines 

with sandwich plates), HS2,HS4 and HIF carburetter gaskets, rocker cover gasket, plus heater take-off 

gasket. The rocker cover gasket will require two small notches to be cut in it to allow for the extra 

Cooper S cylinder head fixings. Valve stem oil seals are not included in the set, leaving customers to 

choose the type and quantity they need and order them separately. 



4 GEG300 GASKET, cylinder head, copper 1 



7 51K1193 NUT, cylinder head to block 10 




9 AEG248 BOLT, cylinder head 1 



11 2K1345 PLUG, oil hole, cylinder head 1 Alternative to 6K808. 

6K808 PLUG, oil hole, cylinder head 1 Alternative to 2K1345. 

12 12G2092 PLUG, water hole 3 

13 AEA771 PLUG, water and dowel hole 2 

14 12G3503 PLUG, cleaning hole 3/2 Qty. decreases for 12G940 head. 

15 2A243 ADAPTOR, by-pass hose, shor t 1 





17 GTG101 GASKET, thermostat housing, cork 1 

GUG705558 GASKET, thermostat housing, paper 1 



preferred for a thermostat housing with sandwich plate (not applicable for Cooper S engines). 


19 FNZ105 NUT 3 


Heater Valve and Fixings 


For details of the heater valves, please see the ‘Heating - Heater Hoses, Water Control Valves and Cables’ 

section in the Cooling area of the Somerford Mini catalogue. 

22 2A180 PLATE, blanking heater take-off in head 1 For models without heater. 

23 88G221B GASKET, heater valve 1 

24 53K402 STUD, heater valve 2 

25 FNZ104 NUT 2 




28 53K487 STUD, manifolds 6 

29 12A1211 WASHER, plain, large, clamping manifolds 4 


31 GHF261 NUT,brass, manifolds to head 6 

51K1177 NUT,brass , manifolds to head, long 6 Alternative; easier to access. 

The standard brass nut GHF261 is the usual fixing for manifolds - being brass it doesn’t sieze on the 

steel manifold studs too easily. The long brass nut 51K1177 first saw light on Mini manifolds when BMC’s 

Competitions Depar tment and Special Tuning wanted a manifold fixing that wasn’t so fiddly to get at. It 

does the job very well and is far easier to do up or undo than the standard nut, but for some reason - 

probably cost - was never adopted on the production line. 


47



48 





32 AEG172 ROCKER COVER, steel, with breather pipe 1 1963-64, open circuit breathing. 

33 AEG512 ROCKER COVER, steel, no breather pipe 1 1964-71, closed circuit breathing. 

34 CAM6822 ROCKER COVER, alloy, without breather 1 Accessory (also MG Metro) item for 

pipe 



contact us for details. Some accessory rocker covers require different fixings from the standard items. 

35 - PLATE, engine name 1 See note belo w. 

- DECAL, engine name 1 See note belo w. 


- DECAL, engine patent 1 See note belo w. 



36 12A402 CAP, oil filler, black plastic, without 1 1963-64 open circuit breathing 

breather models . 

37 13H2296 CAP, oil filler, black plastic, with breather 1 1964-71 closed circuit breathing 

models. 

38 GFE6007 CAP, oil filler, red plastic, with breather 1 For CAM6822 alloy rocker cover. 

39 12A403 SEAL, plastic oil filler cap 1 For 12A402 and 13H2296 caps. 

40 GEG417 GASKET, rock er cover, original 1 With notches to clear head fixings. 

GEG401 GASKET, rocker cover, replacement 1 Must be notched before fitting. 


Includes chrome nuts, chrome distance pieces, chrome cup washers and rubber bushes. Originally for 

alloy rocker covers such as CAM6822,may also be used to enhance restored steel rocker covers. 








46 12A1968 LIFTING EYE, engine, temporary fitment 2 Fit to engine only while lifting work 

is taking place . 




Note that 12G1926 and 12G1927 are the late design of pedestal - there were several earlier designs in 

differing materials, none of which are now available. The outstanding design difference is that both types 

of the late pedestals have oil holes in them, which certainly isn’t the case with the untapped pedestal in 

earlier designs. This means that late type pedestals can be swapped around in their relative positions, 

wherever the tapped pedestal needs to be to secure the rocker shaft in place (early rocker shafts 

secured by grub screw to the pedestal closest to the front of the engine, whereas the later shaft - the 

only one now available - secures to the second pedestal along). Swapping the first two pedestals, if they 

are of early design, in order to fit a later rocker shaft will result in no oil feed to the rocker shaft or 

rockers... 


50 2A515 PLATE, securing screw 1 Original item. 

51 2A259 PLATE, securing screw 1 Replacement item. 


53 CHS522 STUD, short, rocker pedestal 2 Inner pedestals. 

54 LNZ205 NUT, nyloc, pedestal to cylinder head 4 

55 PWZ105 WASHER, plain 3 Not used on tapped pedestal. 

56 PWZ106 WASHER, plain 3 Not used on tapped pedestal. 

57 AEG399 ROCKER SHAFT ASS’Y 1 Original item. 

58 12A1950 ROCKER SHAFT 1 Replacement item. 



61 12G1221 ROCKER, forged 8 Original item. 

62 CAM289 ROCKER, scintered 8 Replacement item. 

Only forged rockers were fitted to Cooper S engines when built. However, after the introduction of the 

scintered rocker on other A Series engines in 1974, either forged or scintered rockers were offered as 

replacement parts. The forged rock er is acknowledged as the stronger of the two and is of course 

correct for originality. However for normal road use it does not matter which type of rocker is used, so 

long as (i) all eight on the rocker shaft are of the same type; (ii) all eight are either the same age from 

the same engine or are new; and (iii) the tappet adjusting screws and nuts, plus the rocker spacing 

washers, are correct for the type of rocker. Note that the forged rock ers have replaceable bushes, 

whereas scintered rockers do not. 

Several designs of high-lift and roller rockers are also available for tuning purposes, along with special 

valve springs to avoid coil binding, if necessary. Please contact Somerford Mini for details of these and 

other engine tuning parts. 

63 2A21 BUSH, rock er 8 Included in forged rocker. 

64 5C2436 RIVET, bush to rocker 8 Included in forged rocker. 

65 AEG167 SCREW, tappet adjusting 8 Use with forged rocker. 

66 NT605061 NUT, locking screw 8 Use with forged rocker. 


68 51K1178 NUT, locking screw 8 Use with scintered rocker. 

69 6K556 SPRING, rocker spacing 3 

70 AEG168 DISTANCE PIECE, exhaust rock er 6 For forged rockers. 

71 2A18 WASHER, double coil, outer ends of shaft 2 For scintered rockers. 

The distance piece AEG168 is used to shim forged rock ers on their shaft correctly over the exhaust valves. 

It is only required on big bore (970, 1071 and 1275cc) cylinder heads, where the valves are spaced 

further apart than is the case on other A Series engines. The correct locations for the six ditance pieces 

are as follows: 

One on either side of each of the outer exhaust rockers (four in total). 

One on the pedestal side of each of the inner exhaust rockers (two in total). 

The wider scintered rockers do not require these shims , so instead rever t to the more usual A Series set 

up of using double coil (or ‘Thackery’) washers at either end of the rocker shaft. 


73 ZPS314 SPLIT PIN, outer ends of shaft 2 

Valve Guides and Valve Seat Inserts 

Originally on the 12A185 and AEG163 cylinder heads the valve guides were different for inlet and exhaust 

valves. The 12G940 head had a single valve guide design, and this is now offered for all Cooper S 

cylinder head applications. This valve guide, 12G1963, will accept the later ‘top hat’ type valve stem oil 

seal (ADU4905) if required and has the classic high-flow ‘bullet nose’ profile at the port end. 

If you are intending to fit non-standard valves in your cylinder head, you will need to be aware that 

12G1963 valve guides are cast iron and will operate only with conventional steel or chromed valve stems . 

They will not work with stainless steel or EN214N valves unless the stems are chromed. 

74 12G1963 GUIDE, inlet and exhaust valve 8 

75 12G1089 INSERT, inlet valve seat 4 Not lead free fuel compatible. 

76 12G2675 INSERT, exhaust valve seat 4 For 12A185 and AEG163 heads . 

TAM2069 INSERT, exhaust valve seat 4 For 12G940 heads; lead free fuel 

compatible. 


As stated in the introduction to this section, the valve stem lengths are particular to the cylinder head 

castings found on Cooper S models, as are exhaust valve diameters. The age of the car provides no 

guarantee as to which cylinder head will be present. Please check your casting number and valve sizes 

before ordering replacements from Somerford Mini. A range of uprated valves , valve springs and caps to 

suit most uses are also available from Somerford Mini; please contact us for details . 

12A185 and AEG163 Cylinder Head Castings 

(originally 1963-69 models) 

77 AEG593 VALVE, inlet, 1 13/32" (35.6mm) dia. 4 Nimonic 80 (EN214N) material. 

78 AEG594 VALVE, exhaust, 1 7/32" (31mm) dia. 4 Nimonic 80 (EN214N) material. 

79 C-AEA525 SPRING SET, valves, outer and inner 1 

80 AEA767 SPRING, valve, outer 8 Included in spring set. 

81 12G1137 SPRING, valve, inner 8 Included in spring set. 


83 AEA653 CAP, upper, valve springs, steel 8 


85 AEG327 OIL SEAL, valve stem 8 

12G940 Cylinder Head Castings 

(originally 1969-71 models) 

86 AEG592 VALVE, inlet, 1 13/32" (35.6mm) dia. 4 

87 12G1322 VALVE, exhaust, 1 5/32" (29.4mm) dia. 4 

CAM4601 VALVE, exhaust, 1 5/32" (29.4mm) dia. 4 Alternative. 

88 C-AEA525 SPRING SET, valves, outer and inner 1 

89 AEA767 SPRING, valve, outer 8 Included in spring set. 

90 12G1137 SPRING, valve, inner 8 Included in spring set. 


92 88G617 CAP, upper, valve springs 8 Original item. 

AEA653 CAP, upper, valve springs , steel 8 Uprated alternative. 


94 AEG327 OIL SEAL, valve stem 4 

Oil seals were usually fitted on the inlet valve stems only, but they can be fitted on exhaust valves too. 

Opinions differ on which is better - the choice is yours. 


49

Oil Pumps and Oil Pressure Relief Valve 


50 


Oil Pumps and Oil Pressure Relief Valve 


Oil Pumps (Manual Gearbox Models) 

Small Bore Engines (848, 997, 998 and 1098cc) 

Oil pumps on small bore A Series engines were manufactured by three different companies and were 

driven by two different couplings from the camshaft. The first manufacturer, Burman, produced a four 

vane, pin driven pump which saw use on the fist Minis built between 1959 and 1961. This pump went 

out of production very early on and may be replaced by either of the other two companies’ pumps, so 

long as the three original fixing screws are also replaced by the later, longer bolts and lock tab. 

From 1961 the oil pump was changed to a rotor/annulus type but was still driven by a pin in the 

camshaft. It was made by either Hobour n-Eaton or Concentric;there are differences between the two 

manufacturers’ products but they are interchangeable , using the same fixing bolts and lock tab. 

The last change occurred towards the end of 1980, when the A Plus camshaft was introduced. This 

camshaft design had a slot in the oil pump driving end into which the oil pump shaft located, replacing 

the previous pin drive. The oil pump was still dual-sourced from the same manufacturers and because 

the pump to block fixing method is the same, Hobourn-Eaton and Concentric pumps will, as with the 

earlier pin drive types, directly replace each other. 

Big Bore Engines (970, 1071 and 1275cc) 

The big bore engine oil pumps were sourced from two manufacturers, Hobourn-Eaton or Concentric. 

Cooper S engines from 1963-69 had a pin drive pump fixed by the same three bolts used on the the 

small bore engine pumps made by the same companies . However, upon the change to star drive oil 

pumps and camshafts in 1969, the Hobourn-Eaton pump became two bolt fixing and the Concentric pump 

became four bolt fixing. This situation continued after 1980 when the oil pump drive changed again to 

the A Plus slot drive type. 

Two and four bolt pumps are interchangeable, so long as the correct drive method is observed and the 

correct quantities of bolts are used. The flanged bolts fixing the oil pumps on 1990s Mini 1275cc 

engines (and Metro engines from 1984) may be used to fix any earlier star drive or slot drive 1275cc 

engine oil pump, replacing the original bolts and washers or lock tabs. 

Oil Pump Interchangeability 

Some standard profile and particularly uprated camshafts are increasingly only available in slot drive 

format, which means if you have an earlier engine you may well have to change your oil pump from pin 

or star drive to a slot drive type; there is no problem doing so, so long as correct fixings are also used. 

It used to be the case, back in the 1960s, that if you wanted a high capacity oil pump you would fit 

the Cooper S item (note that high capacity does not mean high pressure; it simply means that more oil 

is pumped around the engine - oil pressure is of course controlled by the oil pressure relief valve). 

However from 1968 all oil pumps e xcluding that fitted to the MG Metro Turbo and ERA Mini Turbo, but 

including replacements for the earlier 1960s types, have been of Cooper S capacity. As a result, if you 

want a high capacity oil pump today, you can fit the GLP110 Metro/Mini Turbo item. 

For those who mix and match their engine components, it is possible to fit a big bore engine oil pump 

in a small bore engine - for example, the Metro Turbo pump. Firstly, the oil pump drive from the 

camshaft must be correct, which means in the case of the Turbo pump you will need a slot drive 

camshaft in your engine. Secondly, star drive and slot drive big bore engine oil pumps are two or four 

bolt fixing, whereas small bore engine oil pumps use three bolts . Some of the oil pumps supplied today 

have five bolt holes, which means they can be fitted with either two, three or four bolts, as appropriate. 

If however your pump has only two or four bolt holes , you will need to drill and tap a small bore 

cylinder block with sufficient holes to accept the pump. 

A big bore Cooper S engine built before 1969 faces the same pump fixing problems if a non-standard 

star drive or slot drive camshaft is to be fitted. The original pin drive pump for this engine is three 

bolt fixing, so to fit a star drive or slot drive oil pump you will need to either ensure that you purchase 

a five bolt hole pump or drill and tap the cylinder block to accept a two or four bolt fixing. Post 1969 

Cooper S engines are ready machined for two or four bolt fixings. 

Lastly, the oil pump in a big bore engine sits in a different position from its small bore equivalent, 

relative to the camshaft. This means that to fit a big bore engine pump in a small bore engine (for 

example , fitting a star drive pump to allow use of a star drive cam), a 12G1127 spacer will be required. 

848, 997, 998 and 1098cc 1959-80 

(pin drive from camshaft) 

1 2A819 OIL PUMP ASSEMBLY, Burman 1 848cc 1959-61. No longer serviced; 

use Hobourn-Eaton or Concentric 

pump with correct bolts and lock tab. 

2 SH604051 SCREW, oil pump to cylinder block 3 848cc 1959-61. Burman pump only. 

3 LWZ304 WASHER, locking 1 848cc 1959-61. Burman pump only. 

4 GLP142 OIL PUMP ASSEMBLY, Hobourn-Eaton or 1 1961-80. 

Concentric 

5 BH604141 BOLT, oil pump to cylinder block 3 1961-80. 

6 12G926 WASHER, tab 1 1961-80. 

7 GUG705560GM GASKET, oil pump to cylinder block 1 

848, 998 and 1098cc A Plus 1980 On 

(slot drive from camshaft) 

8 GLP139 OIL PUMP ASSEMBLY, Hobourn-Eaton 1 

or Concentric 

9 BH604141 BOLT, oil pump to cylinder block 3 

10 12G926 WASHER, tab 1 If fitted. 


970, 1071 and 1275cc Cooper S 1963-69 

(pin drive from camshaft) 

12 AEG178 OIL PUMP ASSEMBLY, Hobourn-Eaton 1 

AEG410 OIL PUMP ASSEMBLY, Concentric 1 

13 BH604141 BOLT, oil pump to cylinder block 3 

14 12G926 WASHER, tab 1 


1275cc Cooper S and 1275 GT 1969-80 

(star drive via ‘spider’ on camshaft) 

16 GLP141 OIL PUMP ASSEMBLY, Hobourn-Eaton 1 

or Concentric 

17 BH604131 BOLT, oil pump to cylinder block 2/4 Qty. 2 for Hobour n-Eaton pump, 

qty. 4 for Concentric pump. 

18 LWZ204 WASHER, locking 2 For Hobourn-Eaton pump. 

19 12G2098 LOCK TAB, upper 1 For Concentric pump. 

20 12G2097 LOCK TAB, lower 1 For Concentric pump. 


22 12G1127 SPACER, oil pump to cylinder block 1 Allows fitment of 1275cc pump to 848, 

998 or 1098cc block (see notes above). 

1275cc A Plus 1980 On 

(slot drive from camshaft) 

23 GLP138 OIL PUMP ASSEMBLY, Hobourn-Eaton 1 Standard capacity. 

GLP110 OIL PUMP ASSEMBLY, Hobourn-Eaton 1 High capacity (MG Metro Turbo pump). 

or Concentric 

24 BH604131 BOLT, oil pump to cylinder block 2/4 1980. Qty. 2 for Hobourn-Eaton 

pump, qty. 4 for Concentric pump. 

25 LWZ204 WASHER, locking 2/4 1980. Qty. 2 for Hobourn-Eaton 


26 TAM1174 BOLT, oil pump to cylinder block 2/4 1990 on. Qty. 2 for Hobourn-Eaton 



28 12G1127 SPACER, oil pump to cylinder block 1 Allows fitment of 1275cc pump to 848, 

998 or 1098cc block (see notes above). 

Oil Pumps (Automatic Gearbox Models) 

Much easier to describe and list than their manual gearbox counterparts, there are in fact only two 

different types of oil pump on automatic Minis: the star drive type and the A Plus slot drive type. 

29 GLP113 OIL PUMP ASSEMBLY, Hobourn-Eaton 1 1964-80; star drive type. 

30 GLP107 OIL PUMP ASSEMBLY, Hobourn-Eaton 1 1980 on; slot drive type (A Plus). 

31 12A1254 SCREW, cap, oil pump to cylinder block 3 


33 22A1185 PIPE ASSEMBLY, oil outlet 1 

34 22A1187 BLOCK, outlet pipe 1 

35 22A1560 O RING, pipe and block 2 

36 22A1562 O RING, pipe to block 1 

Oil Pressure Relief Valve 



The ball above may be used in place of the standard fitment plunger to guard against a sticking relief 

valve (something that the plunger is prone to do, given dirt or metal particles in the oil). It must, 

however, be used in conjunction with the shorter and stronger AEA536 spring. 

39 6K853 SPRING, oil pressure relief valve 1 Standard fitment. 

40 AEA536 SPRING, oil pressure relief valve 1 Uprated fitment, plus 1961-71 Cooper 

and Cooper S models. 




Models fitted with an oil pressure gauge employ a metal pipe between an adaptor on the pressure switch 

tapping on the cylinder block and the hose running to the gauge itself: 

44 CAM4202 PIPE ASSEMBLY, oil pressure 1 

45 ACA5419 OLIVE, union 1 Included in pipe assembly. 

46 ACA5422 NIPPLE, union 1 Included in pipe assembly. 

47 ACA5421 NUT, union 1 Included in pipe assembly. 

48 PCR211 CLIP, pipe securing 1 

49 2A269 ADAPTOR, pipe to cylinder block 1 Original fitment. 

OA ADAPTOR, pipe to cylinder block 1 Alternative fitment. 

To enable operation of both an oil pressure gauge and oil pressure light, a tee piece may be screw ed in 

to the cylinder block,accepting both the pressure pipe adaptor and pressure warning light switch: 

50 TP TEE PIECE, pipe and switch to block 1 

51 2K4956 WASHER, fibre 1 


51

Oil Filters and Oil Pipes 


52 




Full Flow and By Pass Oil Filters 

(Manual Gearbox Models, 1959-73) 

In the period between 1959 and 1964, several different ‘Full Flow’ cannister type oil filter assemblies 

with clamped replaceable paper elements were fitted as alternatives in production. One was made by 

Tecalamit, the others by Purolator (the filter head usually has the manufacturer’s name cast into it). 

From 1964 until 1973, Purolator ‘By-Pass’ assemblies with unclamped paper elements were used 

exclusively. The 1964-69 unclamped element types had a pressure switch to warn drivers if the filter 

was in poor condition, which was a good idea in theor y. Both the strength and weakness of the by-pass 

type of filter is that if a paper filter element becomes so loaded up with dirt and debris that the oil 

can’t flow through it, the build up of pressure eventually lifts the element off its pressure plate allowing 

a high proportion of unfiltered oil to flow straight out again - a strength because the flow of oil to the 

engine is maintained even though the filter is blocked, and a weakness because the maintained flo w 

consists of unfiltered oil full of harmful metallic particles , usually generated by the gearbox internals. 

The pressure switch was designed to warn the driver of an impending filter blockage in plenty of time 

before the situation turned into an injection of grinding paste into the engine. Unfortunately it was 

wildly inaccurate under certain conditions - especially when the oil was cold and thick - and spent much 

of its time warning the driver unnecessarily. It was subsequently dropped again from 1969, although a 

switch-less by-pass type filter continued to be fitted until 1973 when the altogether more practical ‘spinon’ 

cartridge type filter took over. 

All Full Flow and By-Pass oil filters are interchangeable, but only as complete assemblies, since the y have 

many differing component par ts (although the paper element itself is always the same). Care must 

therefore be taken to identify (i) the manufacturer and (ii) for Purolator types , the material the sump is 

made from, before ordering parts for them. 

Tecalemit Full Flow Clamped Element Assemb ly 

1959-64 (without pressure switch) 

1 GFE103 ELEMENT, oil filter, with seal 1 

2 12A1591 SEAL, sump to head 1 Included with element. 

3 17H945 HEAD ASS’Y, oil filter, without pressure 1 

switch 

4 37H436 SUMP, oil, steel 1 

5 7H147 PLATE, clamping element 1 

6 7H1756 SEAL, clamp plate, felt 1 

7 2A700 CIRCLIP, clamping plate 1 

8 7H1761 WASHER, dished, clamp plate 1 

9 17H942 PLATE, pressure 1 

10 7H1758 SEAL, pressure plate , felt 1 

11 7H1765 WASHER, plain 1 

12 7H1764 SPRING , pressure plate 1 

13 17H943 BOLT, centre 1 

14 7H1759 SEAL, bolt to sump 1 

15 17H2877 CIRCLIP, bolt retaining 1 

35 27H1717 SUMP, oil, die cast 1 Use correct collar and seal on centre 

bolt. 

17H1169 SUMP, oil,steel 1 Use correct collar and seal on centre 

bolt. 

17H8892 SUMP, oil, aluminium 1 Use correct washer and seal on 

centre bolt. 


37 7H28 SEAL, pressure plate, rubber 1 


39 500319 SPRING, pressure plate 1 


41 17H1172 COLLAR, sump to seal 1 For die cast or steel sump. 

PWZ106 WASHER, plain 1 For aluminium sump. 

42 508380 SEAL, bolt 1 For die cast or steel sump. 

17H2281 SEAL, bolt 1 For aluminium sump. 


Oil Filter Head Fixings 

44 88G402 GASKET, oil filter head to cylinder block 1 

45 53K615 STUD, oil filter head to cylinder block 2 

46 FNZ106 NUT, plain 2 Alternative to nyloc nut; use with 

locking washer. 

47 LWZ306 WASHER, locking 2 Use with plain nut. 

48 LNZ206 NUT, nyloc 2 Alternative to plain nut; use with 

plain washer. 

49 PWZ106 WASHER, plain 2 Use with nyloc nut. 

Oil Filter to Cylinder Block Pipe 

This pipe is not required if an oil cooler is fitted. For oil coolers, hoses and fittings, see the ‘Cooling - Oil 

Coolers’ section in the Cooling and Heating area of the Somerford Mini catalogue. 

50 88G538 PIPE ASS’Y,oil filter head to cylinder 1 

block 

51 TCZ106 ADAPTOR, pipe to oil filter head 1 Original type. 

TAM2119 ADAPTOR, pipe to oil filter head 1 Replacement type. 

52 2A715 BOLT, banjo, pipe to cylinder block 1 

53 AED172 WASHER, sealing banjo union 2 Original copper washer. 

LYF10017 WASHER, sealing banjo union 2 Alternative bonded metal/rubber 

washer. 

Spin-On Oil Filters 

(Manual Gearbox Models, 1973 On) 

From 1973 until 1996 a filter head accepting a ‘spin-on’ cartridge type filter was fitted. The 1973-92 

filter heads can be fitted to pre-1973 engines to allow them to take a non-period appearance , but 

certainly more practical, spin-on filter. Note that the filter head to cylinder block studs must be changed 

as well. 

Purolator Full Flow Clamped Element Assembly 

1959-64 (without pressure switch) 



18 17H1170 HEAD ASS’Y, oil filter, without pressure 1 

switch 

19 17H1169 SUMP, oil, steel 1 

20 17H1152 SEAL, clamp plate, rubber 1 

21 17H1150 PLATE, clamping element 1 

22 17H1167 CIRCLIP, clamping plate 1 


24 7H28 SEAL, pressure plate , rubber 1 


26 500319 SPRING , pressure plate 1 


28 17H1172 COLLAR, sump to seal 1 

29 508380 SEAL, bolt to sump 1 


Purolator By-Pass Unclamped Element Assembly 

1959-64 and 1969-73 (without pressur e switch) 

1964-69 (with pressur e switch) 



33 17H9463 HEAD ASS’Y, oil filter, without pressure 1 1959-64 and 1969-73. 

switch 

34 37H1528 HEAD ASS’Y, oil filter, with pressure switch1 1964-69. 

Carburetter model filter heads fitted between 1973 and 1992 are completely interchangeable. The filter 

head fitted from 1991 to 1996 (injection models, plus 1992-94 carburetter models) is not so easily 

interchangeable with the earlier types, since it has a different connection to the cylinder block oil pipe. 

The oil filter to cylinder block pipe is not required if an oil cooler is fitted. For oil coolers, hoses and 

fittings, see the ‘Cooling - Oil Coolers’ section in the Cooling and Heating area of the Somerford Mini 

catalogue. 

Cars fitted with a spin-on type oil filter head can very easily be fitted with the MG Metro/Metro T urbo oil 

cooler, which simply fits as a sandwich plate between the filter head and the filter. It is very tempting to 

use one - particlularly if you are fitting a Metro engine with one of these devices already on it in your 

Mini. There is a note of caution to be heeded here, though. The Metro oil cooler works as a heat 

exchanger between the oil and the engine’s cooling water (since it is also plumbed into the cooling 

system), rather than between the oil and air as is the case with a conventional oil cooler. While the 

Metro has a very efficient front-mounted radiator which can cope with cooling water that’s been heated 

both by the engine and the oil, the smaller, side-mounted Mini radiator can struggle to deal with it. 

Upon the major engine revamp for the 1997 model year (i.e. the star t of multi point injection 

production),the whole idea of an oil filter head was abandoned in favour of a spin-on filter which 

attached directly to the cylinder block - actually a throw-back to the old 1275cc Morris Marina cylinder 

block of the 1970s. There simply wasn’t any room for an oil filter head behind the new, front-mounted 

radiator on the MPi Mini. 

1973-92 Spin-On Cartridge Assembly 

(all carburetter engines except 1275cc 1992-94) 

54 GFE166 CARTRIDGE, oil filter, with seal 1 Original equipment. 

GFE21 CARTRIDGE, oil filter, with seal 1 Premium ‘Hitech’ type . 

55 12A2032 HEAD ASSEMBLY, oil filter 1 1973-88. 

TAM2097 HEAD ASSEMBLY, oil filter 1 1988-92; will replace 12A2032. 


53



54 




1973-92 Spin-On Cartridge Assembly (continued) 

56 GUG705553GM GASKET, oil filter head to cylinder block 1 

57 CHS2613 STUD, oil filter head to cylinder block 2 

58 FNZ106 NUT 2 



61 88G538 PIPE ASS’Y, oil filter head to cylinder 1 1973-80 (pre-A Plus). 

block 

TAM2106 PIPE ASS’Y, oil filter head to cylinder 1 1980-92 (A Plus). 

block 

62 TCZ106 ADAPTOR, pipe to oil filter head 1 1959-88. 

TAM2119 ADAPTOR, pipe to oil filter head 1 1988-92; will replace TCZ106. 




washer. 

1991-96 Spin-On Cartridge Assemb ly 

(single point injection engines 1991-96 and 

1275cc carburetter engines 1992-94) 

65 GFE166 CARTRIDGE, oil filter, with seal 1 Original equipment. 

GFE21 CARTRIDGE, oil filter, with seal 1 Premium ‘Hitech’ type. 

66 LPX10026 HEAD ASSEMBLY, oil filter 1 Casting mark ed LPX10027. 

67 GUG705553GM GASKET, oil filter head to cylinder block 1 

68 LYG10008 BOLT, flanged, oil filter head to cylinder 2 

block 

69 LQP10033 PIPE, oil filter head to cylinder block 1 

70 LYH10014 NUT, tube, pipe union 2 

71 LZB10017 SEAL, rubber, pipe 2 

1997 On Spin-On Cartridge Assembly 

(multi point injection and single point injection engines) 

72 LPW100180 CARTRIDGE, oil filter, with seal 1 Original equipment. 

GFE26 CARTRIDGE, oil filter, with seal 1 Premium ‘Hitech’ type. 

73 CAM5331 ADAPTOR, oil filter to cylinder block 1 

By-Pass Oil Filters 

(Automatic Gearbox Models) 

Purolator By-Pass Unclamped Element Assembly 

1964 (without pressure switch) 

1965 On (with pressure switch) 

For details of the workings of by-pass unclamped paper element type filters and the ‘filter condition 

warning’ pressure switch, please see the manual gearbox section on the previous page. On automatic 

Minis the replaceable paper element type filter (larger than the version used on manual cars) lasted 

throughout the model’s production life , unlike the manual gearbox models which changed over to the 

infinitely more simple spin-on filter in 1973. 

Also unlike manual models, the filter is attached to the gearbox (on the front cover) on Mini automatics, 

the principle being to supply the freshly filtered oil to the delicate valve block through the gear selector 

valve and the gearbox regulator valve before it reaches the engine via the torque converter oil supply 

route and the engine’s oil pressure relief valve. 

This means that because the oil pump on a Mini automatic is still in the engine, as in a manual Mini, 

the oil has to be drawn up from the sump (gearbox), through the pump and then back down to the 

gearbox again to reach the oil filter. The first automatics of 1964-65 had an adaptor and pipe running 

from what would have been the oil filter head mounting face on a manual engine down to the gearbo x. 

From mid-1965 this was dispensed with in favour of a simple, short oil pipe running internally between 

the cylinder block and gearbox (which can be found in the Automatic Transmission section of the 

Somerford Mini Catalogue) leaving subsequent automatic-type engines wearing a blanking plate where the 

adaptor had been fitted. At the same time an external oil supply pipe more similar in design to that 

used on a manual power unit was also fitted. 

When changing the oil on a Mini automatic, note that while the total capacity of engine and gearbox is 

13 pints, only approximately 9 pints can be drained and refilled. The remainder is ‘trapped’ b y the 

gearbox low pressure valve, which is shut when the engine is not turning, in the torque converter (the 

idea being to stop drain back from the torque converter to the sump, which would otherwise result in a 

‘dry’ torque converter and no drive when the engine is restarted). 

When using the gearbox dipstick to check the oil level, the marks on the dipstick are calibrated for a 

full level of 9 pints, with a one pint difference between the minimum and maximum marks. Remember 

that unlike a manual power unit where you can simply open the bonnet and check the level with the 

dipstick, an automatic power unit must be run for a couple of minutes and then left to stand for a 

minute before checking the oil level. Failure to do so results in a substantially inaccurate reading. 

Also note that when changing the oil filter, the filter sump (or ‘bowl’) lies on its side on the front of the 

Mini automatic gearbox, rather than being vertical (as is usually the case with oil filters). As it is removed 

from the filter head a considerable quantity of oil will flow out - either straight onto the garage floor, or 

if you’re prepared, into a container on the garage floor. If you’ve done the job before , you will already 

know this. If you haven’t, this note has just saved you from a nasty surprise. 



76 27H6800 HEAD ASS’Y,oil filter, without pressure 1 1964. 

switch 

37H1480 HEAD ASS’Y,oil filter, with pressure switch 1 1965 on. 

77 37H140 SUMP, oil 1 

78 500439 PLATE, pressure 1 

79 7H28 SEAL, pressure plate, rubber 1 


81 500319 SPRING, pressure plate 1 


83 17H1172 COLLAR, sump to seal 1 

84 508380 SEAL, bolt 1 


Oil Filter Head Fixings 

86 GUG705552GM GASKET, oil filter head to gearbox front 1 

cover 

87 22A1001 O RING, oil filter head 2 1964-69; if required. 

88 BH507131 BOLT, oil filter head to gearbox front 1 

cover, shor t 

TAM1188 BOLT, oil filter head to gearbox front 1 Alternative to BH507131. 

cover, shor t 

89 BH507301 BOLT, oil filter head to gearbox front 1 

cover, long 


Cylinder Block to Gearbox Case (Oil Filter) Adaptor 

1964 (848cc) 

91 22A1197 ADAPTOR, oil, cylinder block to gearbox 1 

case 

92 22A811 O RING, adaptor to gearbox case 1 

93 88G402 GASKET, adaptor to cylinder block 1 

94 SH506101 SCREW, adaptor to cylinder block 2 

Cylinder Block to Gearbox Case (Oil Filter) Pipe 

1965-92 (848 and 998cc) 

95 88G539 PIPE ASS’Y,oil, cylinder block to gearbox 1 1965-80 (pre-A Plus). 

case 

AHU2396 PIPE ASS’Y,oil, cylinder block to gearbox 1 1980-92 (A Plus). 

case 

96 22G791 ADAPTOR, pipe to gearbox case 1 1965-88. 

DAM7601 ADAPTOR, pipe to gearbox case 1 1988-92; will replace 22G791. 





washer. 

100 22A1203 PLATE, blanking cylinder block oil filter 1 

face 

101 88G402 GASKET, blanking plate 1 

102 SH506071 SCREW, blanking plate to block 2 

103 12G1058 WASHER, sealing 2 

Cylinder Block to Gearbox Case (Oil Filter) Pipe 

1992 On (1275cc) 

104 LQP10038 PIPE ASS’Y,oil, cylinder block to gearbox 1 

case 

105 LYH10014 NUT,tube, pipe union 1 

106 LZB10017 SEAL, rubber, pipe 1 

107 DAM7601 ADAPTOR, pipe to gearbox case 1 


109 TGW100020 ADAPTOR, gearbox case 1 1997 on. 

110 22A1563 O RING, adaptor to gearbox case 1 1997 on. 

111 LZB100350 SEAL, adaptor 1 1997 on. 


55

Engine Mountings 


56 




Engine Mounting Kits 

Mounting kits include both engine mountings with fixing hardware, plus gearbox mountings if applicable. 

1 EMK001 ENGINE MOUNTING KIT 1 Manual, direct gearchange. 

2 EMK002 ENGINE MOUNTING KIT 1 Manual, remote gearchange . 

3 EMK003 ENGINE MOUNTING KIT 1 Manual, rod gearchange. 

4 EMK004 ENGINE MOUNTING KIT 1 Automatic. 

Engine Mountings - Manual Gearbox Type 

Right Hand Engine Mounting 

All Models 

5 21A1902 MOUNTING , engine 1 

6 SH505061 SCREW, mounting to clutch cover 3 


8 SH605061 SCREW, mounting to subframe 2 


10 FNZ105 NUT 2 

Left Hand Engine Mounting 

1959-69 (not Cooper, Cooper S or alternator fitted models) 

11 22A30 BRACKET, mounting engine and radiator 1 

12 53K1474 STUD, bracket and speedometer pinion 3 

housing to gearbox 

13 53K551 STUD, bracket to speedo pinion housing 1 Not 848cc 1959-68. 

53K545 STUD, bracket to speedo pinion housing 1 848cc 1959-68. 

14 FNZ505 NUT, bracket to speedo pinion housing 4 



17 SH605051 SCREW, mounting to bracket 3 


19 FNZ105 NUT 1 



22 FNZ105 NUT 2 


1969 On (plus earlier alternator fitted models) 

1961-71 (Cooper and Cooper S) 


24 BH605341 BOLT, bracket to adaptor 2 


26 12A360 ADAPTOR, bracket to speedo pinion housing 1 

27 53K1474 STUD, bracket and speedo pinion housing 3 

to gearbox 

28 53K551 STUD, bracket to speedo pinion housing 1 

29 12G1319 SCREW, bracket to speedo pinion housing 1 Alternative to 53K551 stud. 

30 FNZ505 NUT, bracket to speedo pinion housing 4/3 Qty. reduced if using 12G1319 screw. 





35 FNZ105 NUT 3 



38 FNZ105 NUT 2 

Engine Mountings - Automatic Gearbox Type 

Right Hand Engine Mounting 

39 22A917 MOUNTING , engine, RH 1 

40 SH605051 SCREW, mounting to torque converter cover 2 




44 FNZ105 NUT 2 



46 SH505051 SCREW, bracket to auxilliar y pump housing 3 


48 22A1018 MOUNTING , engine, LH 1 





53 FNZ105 NUT 2 

Gearchange Mountings 

Remote Gearchange 1961-73 

54 21A956 MOUNTING , rubber, remote control 1 

55 SH505061 SCREW, coarse thread,mounting to remote 2 


57 21A745 BRACKET, mounting to floor 1 

58 FNZ106 NUT,mounting to bracket 1 


60 PWZ206 WASHER, plain, large 1 

61 SH605061 SCREW, bracket to floor 3 

62 53K3439 WASHER, ‘D’ 3 



65 FNZ105 NUT 3 

Rod Gearchange 1973 On 

66 22G2026 BRACKET, gearchange housing to mountings 1 

67 42H1214 BUSH, gearchange housing, lower 2 

68 BT606281 BOLT, bracket to housing 1 

69 LNZ106 NUT, nyloc 1 

70 22G2205 MOUNTING, rubber 2 

71 FNZ105 NUT, mounting to floor 2 


Engine Steady Bars 

Upper Right Hand Engine Steady Bar 1959-62 

73 2A5874 BAR, engine steady 1 

74 2A5872 BUSH, one-piece , bar to engine 1 

75 2A5871 SPACER, bush 1 

76 2A5869 BRACKET, bar retaining 1 

77 21A1107 STRIP, packing 1 

78 BH605131 BOLT, bracket and bar to engine 1 

79 SH605061 SCREW, bracket to engine 1 


81 CRC5329 BUSH, bar to dash crossmember 2 Standard fitment. 

CRC5329KIT BUSH KIT, bar to dash crossmember 1 Includes a pair of standard bushes and 

nylon cones. 

CRC5329HD BUSH, bar to dash crossmember 2 Heavy duty r ubber; see notes later in 

section. 

82 2A5873 STUD, bar to dash crossmember 1 

Removal of this stud requires slackening off the plate under the brake and clutch master cylinders, with 

all the difficulty involved in doing so (think clevis pins - or think ‘not for me’ if you’ve never done it). 

Far better to use the post-1970 bolt (BH605151) and spacer (21A1108) in place of the stud. 

83 FNZ105 NUT 2 


Upper Right Hand Engine Steady Bar 1963-70 

85 21A1109 BAR, engine steady, short 1 Manual models. 

86 21A1817 BAR, engine steady, long 1 Automatic models. 

87 SBFK001 FITTING KIT, upper RH steady bar 1 Includes heavy duty bushes plus fixings. 

88 CRC5329 BUSH, bar to engine and dash crossmember 4 Standard fitment. 

CRC5329KIT BUSH KIT, bar to engine and dash 2 Includes a pair of standard bushes and 

crossmember 

nylon cones. 

CRC5329HD BUSH, bar to engine and dash 4 Heavy duty r ubber; see notes later in 

crossmember 

section. 

89 21A1108 SPACER, bush 1 


91 21A1107 STRIP, packing 1 

92 21A1106 WASHER, packing 1 




96 2A5873 STUD, bar to dash crossmember 1 

Unless you’re after originality at all costs, Somerford Mini would advise you to follow the tip in the 1959- 

62 listing above and use a bolt instead of the dash crossmember stud. 

97 FNZ105 NUT 2 


Upper Right Hand Engine Steady Bar 1970 On 

99 21A1109 BAR, engine steady, short 1 Manual, except 1275cc 1990 on. 

100 21A1817 BAR, engine steady, long 1 Automatic; 1275cc manual 1990 on. 

101 ERA1020 BAR, engine steady, adjustable 1 Alternative (original ERA Mini Turbo item). 

The Mini Turbo adjustable steady bar permits fine adjustment of the engine position to create clearance 

for a turbocharger or other non-standard under bonnet equipment. 

102 SBFK002 FITTING KIT, upper RH steady bar 1 Includes heavy duty bushes plus fixings. 

103 CRC5329 BUSH, bar to engine and dash crossmember 4 1970-98 standard fitment. 

CRC5329KIT BUSH KIT, bar to engine and dash 2 Includes a pair of standard bushes 

crossmember 

and nylon cones. 

CRC5329HD BUSH, bar to engine and dash 4 Heavy duty r ubber; see notes later in 

crossmember 

section. 

104 21A1108 SPACER, bush 2 1970-98. 


57



58 




105 KKF101320 BUSH, bonded, bar to engine and dash 2 1998 on. 

crossmember 

The bonded one-piece bushes first fitted in 1998 replaced both the previous ‘top hat’ bushes and their 

spacers. They can be fitted to pre-1998 steady bars. Alternatively, post-1998 cars can be retro-fitted 

with ‘top hat’ bushes and spacers. Whichever, Somerford Mini’s recommendation for longevity is to fit the 

USBK001 steady bar heavy duty bush kit shown later in this section to all models! 





110 PWZ305 WASHER, plain, large 1 If fitted. 

111 BH605151 BOLT, bar to dash crossmember 1 

112 FNZ105 NUT 1 


Lower Right Hand Rear Steady Bar 

848cc 1973-78 

998cc 1973-76 

1098cc 1975-76 

1275cc 1972-78 

Introduced at the same time as the rod change gearbox, the lower RH rear steady bar was intended to 

replace the engine bracing so well effected by the previous gearbox’s remote change housing. Since it 

secures at one end to existing studs and nuts on the power unit and on the other end to a simple hole 

in the subframe rear leg, it can be easily installed on the majority of Minis, if desired. 

114 ESK009 STEADY BAR KIT, lower RH rear 1 Includes bar, bracket, bushes, spacers, 

bush bolts, washers and nuts. 

115 21A2569 BAR, engine steady, RH rear, lower 1 

116 21A2763 BRACKET, bar to flywheel housing 1 

117 CRC5329 BUSH, bar to flywheel housing bracket 4 Standard fitment. 

and subframe 

CRC5329KIT BUSH KIT, bar to flywheel housing 2 Includes a pair of standard bushes 

bracket and subframe and nylon cones . 

CRC5329HD BUSH, bar to flywheel housing bracket 4 Heavy duty rubber ; see notes later in 

and subframe 

section. 

118 31G1085 SPACER, bush 2 

119 BH606181 BOLT, bar to flywheel housing bracket 2 

and subframe 


121 PWZ106 WASHER, plain, small 2 


123 FNZ106 NUT 2 

Lower Left Hand Rear Steady Bar 

998 and 1098cc 1976-78 

For 1976 it was decided to replace the lower RH rear steady bar on 998 and 1098cc models by fitting 

a similar set up on the LH side of the engine, again anchoring to a subframe leg. The lower LH rear 

steady bar assembly can also be easily fitted to many Minis, if required. The factory did not fit it to 

848cc or 1275cc Minis - both soldiered on with the RH bar until the next design appeared in 1978. 

124 ESK008 STEADY BAR KIT, lower LH rear 1 Includes bar, bracket, bushes, spacers, 

bush bolts, washers and nuts. 

125 21A2787 BAR, engine steady, LH rear, lower 1 

126 21A2785 BRACKET, bar to gearbox 1 

127 CRC5329 BUSH, bar to gearbox bracket and subframe 4 Standard fitment. 

CRC5329KIT BUSH KIT, bar to gearbox bracket and 2 Includes a pair of standard bushes and 

subframe 

nylon cones. 

CRC5329HD BUSH, bar to gearbox bracket and 4 Heavy duty rubber ; see notes later in 

subframe 

section. 


129 BH606181 BOLT, bar to gearbox bracket and subframe 2 




133 FNZ106 NUT 2 

Lower Right Hand Front Steady Bar 

All Models 1978 On 

The final variant of the lower steady bar, running forwards from the gearbox to the front crossmember 

of the subframe, appeared in 1978 and was fitted to all Minis up to 2000. It replaced both previous, 

rearward facing, versions. When the 1275cc engine was reintroduced in the Mini in 1990, the engine 

position was moved slightly so the lower RH steady bar for all 1990s 1275cc Minis is slightly shorter (by 

1/2") than for all other models. Incidentally, looking further back in this section of the catalogue, that’s 

why 1990s 1275cc Minis had the longer (previously automatic models only) upper steady bar. 

The good news for owners who already have one on their car is that the lower RH front steady bar 

works better than the previous two rearward facing designs; the bad news is that if you have a pre-1978 

car, unless you also ha ve a post-1978 front subframe with the necessary bracketry welded to it, it 

wouldn’t be easy to fit one. 

134 FAM2758 BAR, engine steady, RH front, lower 1 Long; not 1275cc 1990 on. 

135 KKH10013 BAR, engine steady, RH front, lower 1 Short; 1275cc 1990 on. 

136 SBFK003 FITTING KIT,lower RH front steady bar 1 Includes heavy duty bushes, plus fixings. 

137 NAM3760 BRACKET, bar to gearbox 1 Std. thickness; not 1275cc 1990 on. 

KKU10080 BRACKET, bar to gearbox 1 Extra thick; 1275cc 1990 on. 

138 CRC5329 BUSH, bar to gearbox bracket and subframe 4 Standard fitment. 

CRC5329KIT BUSH KIT, bar to gearbox bracket and 2 Includes a pair of standard bushes and 

subframe 

nylon cones. 

CRC5329HD BUSH, bar to gearbox bracket and 4 Heavy duty r ubber; see notes later in 

subframe 

section. 


140 BH606171 BOLT, bar to gearbox bracket and subframe 2 




144 FNZ106 NUT 2 

Heavy Duty Steady Bar Bushes 

Soft or disintegrated steady bar bushes are one of the most frequent problems on Minis. Identifiable by a 

knock from the dash panel upon sharp throttle movements, loose bushes also result in jerky acceleration 

when the engine ‘snatches’ on the throttle cable - which then causes further bush deterioration. 

The best solution is harder, more resiliant bushes - but beware! Use of very hard or solid bushes may be 

acceptable for out-and-out performance Minis, but they do result in loss of refinement in a road-going car 

and can even cause premature failure of steady bar securing bolts or brackets unless careful fitting and 

maintenance is carried out. Somerford Mini recommends the use of their heavy duty harder (but not too 

hard) rubber bushes for all road-going Minis , pro viding greatly improved resiliance to wear without 

increasing stress on the steady bar and its fixings. The bushes utilise standard spacer tubes and bolts . 

The Somerford Mini heavy duty steady bar bushes are available in an upper steady bar bush kit (four 

bushes and two bush spacers), or as individual bushes for fitment to either upper or lo wer steady bars . 

Note that they are not suitable for fitment to the engine end of original 1959-62 upper steady bars . 

145 USBK001 BUSH KIT, upper steady bar, harder r ubber 1 Includes four bushes and two spacers. 

146 CRC5329HD BUSH, steady bar, harder rubber 1 For upper or lower steady bars. 

Included in USBK001 kit. 

Broken Steady Kits 

What’s even more frustrating than worn out upper steady bar bushes is one or both of the mounting 

bolts shearing off in the cylinder block when you try to replace them! Sometimes one or both block 

bolts have even been sheared beforehand by the shock caused by ineffective bushes. Either way, a classic 

situation of a five minute job turning into a major exercise can result if engineering workshop techniques 

or tools such as ‘easy-outs’ are required to remove the remainder of the bolt(s). Somerford Mini can 

supply an easy-to-fit mounting bracket assembly,bypassing the offending engine block bolt holes. 

The four broken steady kits provide alternatives for use on cylinder blocks where either the longer bolt 

only or both bolts have broken, on engines without or with a crankcase breather on the flywheel housing. 

Each kit includes an adaptor bracket, plus the bar retaining bracket with appropriate bolts and washers. 

147 ESK003 BROKEN STEADY KIT,for sheared 1 Engines without flywheel housing 

longer bolt 

breather. All models 1959-69; not 

1275cc 1969 on. 

ESK004 BROKEN STEADY KIT, for two sheared 1 Engines without flywheel housing 

bolts 

breather. All models 1959-69; not 

1275cc 1969 on. 

ESK006 BROKEN STEADY KIT,for sheared 1 Engines with flywheel housing 

longer bolt 

breather. 1275cc 1969 on. 

ESK005 BROKEN STEADY KIT, for two sheared 1 Engines with flywheel housing 

bolts 

breather. 1275cc 1969 on. 

Upper Left Hand Engine Steady Bar Kits 

Really only recommended for very fast road or competition use, these steady bar kits mount at the 

opposite end of the engine, supplementing the standard RH steady bar. Attachment methods vary in 

detail, since the Mini was never originally designed for them, but they all share the principle of bracing 

the engine between the thermostat housing and the left hand end of the dash crossmember. Kits include 

steady bar,bushes , bush fixings, attachment brackets and extra bracket fixings (as appropriate). 

148 ESK001 STEADY BAR KIT, upper LH (fixes to 1 RH drive 848, 997, 998 and 1098cc. 

thermostat housing, manifold stud and 

heater pipe plate) 

ESK001LHD STEADY BAR KIT, upper LH (fixes to 1 LH drive 848, 997, 998 and 1098cc. 

thermostat housing, manifold stud and 

dash crossmember) 

ESK002 STEADY BAR KIT, upper LH (fixes to 1 RH drive 1275cc without thermostat 

thermostat housing, manifold stud and housing sandwich plate. 

heater pipe plate) 

ESK002LHD STEADY BAR KIT, upper LH (fixes to 1 LH drive 1275cc without thermostat 

thermostat housing and dash crossmember) housing sandwich plate. 

ESK007 STEADY BAR KIT, upper LH (fixes to 1 RH drive 1275cc with thermostat 

thermostat housing and heater pipe housing sandwich plate. 

blanking plate) 

ESK007LHD STEADY BAR KIT, upper LH (fixes to 1 LH drive 1275cc with thermostat 

thermostat housing and dash crossmember) housing sandwich plate. 


59

Brief Mini Production History 

This list is intended to assist some owners who are trying to establish year and model of their Mini. 

However, while the list may seem comprehensive, it isn’t. Just like everything else to do with the Mini 

when you look at its 40 year history, to come up with every last derivative, complete with corresponding 

chassis number (or vehicle identification number) prefix, would take several pages! However, limited 

editions excepted, it details the Mini models covered by this catalogue and is a fair representation of 

models down through the years. 

It does not cover models specific to certain markets that were locally assembled (e.g. Innocenti, Authi, Cord 

and Belgium, South Africa and Australia assembled vehicles). It also does not include certain short-lived 

niche models like the ERA Mini Turbo. 

Note that ear lier MkI expor t models were often badged ‘850’ rather than ‘Mini’ or ‘Seven’, and that the 

later 1980s/1990s City models were usually known in Europe as Special and in Japan as Sprite . 

Model Years Chassis No./ Commencing 

Built VIN Prefix Chassis No./VIN 

Austin and Morris Mk I Saloons 1959-67 

Austin Seven (850) 1959-62 A-A2S7 101 

Austin Mini (850) 1962-67 A-A2S7 197201 

Austin Seven De Luxe (850) 1959-62 A-A2S7 101 

Austin Mini De Luxe (850) 1962 A-A2S7 197021 

Austin Super Seven (850) 1961-62 A-A2S7S 125538 

Austin Super Mini (850) 1962 A-A2S7S 197021 

Austin Mini Super De Luxe (850) 1962-64 A-A2S7S 307125 

Austin Mini De Luxe (850) 1964-67 A-A2S7 640203 

Austin Seven/Mini Cooper (997) 1961-64 C-A2S7 138301 

Austin Mini Cooper (998) 1963-67 C-A2S7 486096 

Austin Mini Cooper S (1071) 1963-64 C-A2S7 384101 



Morris Mini Minor (850) 1959-67 M-A2S4 101 

Morris Mini Minor De Luxe (850) 1959-62 M-A2S4 101 

Morris Super Mini Minor (850) 1961-62 M-A2S4S 75573 

Morris Mini Minor Super De Luxe (850) 1962-64 M-A2S4S 148817 

Morris Mini Minor De Luxe (850) 1964-67 M-A2S4 296257 

Morris Mini Cooper (997) 1961-64 K-A2S4 138311 

Morris Mini Cooper (998) 1963-67 K-A2S4 491251 

Morris Mini Cooper S (1071) 1963-64 K-A2S4 384101 



Austin and Morris Mk II Saloons 1967-70 

Austin Mini Mk II 850 1967-69 A-A2SB 1068001 

Austin Mini Mk II 850 Super De Luxe 1967-69 A-A2SB 1068001 

Austin Mini Mk II 1000 Super De Luxe 1967-69 A-A2SB 1068001 

Austin Mini Cooper Mk II (998) 1967-69 C-A2SB 1068151 

Austin Mini Cooper S Mk II (1275) 1967-70 C-A2SB 1068451 

Morris Mini Mk II 850 1967-69 M-A2S6 507001 

Morris Mini Mk II 850 Super De Lux e 1967-69 M-A2S6 507001 

Morris Mini Mk II 1000 Super De Lux e 1967-69 M-A2S6 507001 

Morris Mini Cooper Mk II (998) 1967-69 K-A2S6 1068197 

Morris Mini Cooper S Mk II (1275) 1967-70 K-A2S6 1068471 

Mini Mk III Saloons 1969-75 

Mini 850 1969-74 X-A2S1 101 

Mini 850 1974-75 X-K2S1 101 

Mini 1000 1969-74 X-A2S1N 101 

Mini 1000 1974-75 X-L2S1N 101 

Mini Cooper S Mk III (1275) 1970-71 X-AD1 101 

Mini Saloons 1976-96 (‘Mk IV’ and Throttle Body Injection or TBi) 

Mini 850 1976-79 X-K2S1 340101 

Mini City (850) 1979-80 X-K2S1 633177 

Mini 850 Super De Luxe 1979-80 X-K2S1N 635039 

Mini 1000 1976-79 X-L2S1N 340554 

Mini 1000 Super 1979-80 X-L2S1N 633285 

Mini City (1000) 1980-82 X-L2S1O 743114 

Mini City E (1000) 1982-88 X-L2S1O 122249 

Mini City (1000) Non Catalyst 1988-92 X-L2S1O 396449 

Mini City (1000) Catalyst 1989-92 X-L2S3O 426565 

Mini HL (1000) 1980-82 X-L2S1N 743004 

Mini HLE (1000) 1982 X-L2S1N 122249 

Mini Mayfair (1000) 1982-88 X-L2S1N 147144 

Mini Mayfair (1000) Non Catalyst 1988-92 X-L2S1N 396449 

Mini Mayfair (1000) Catalyst 1989-92 X-L2S3N 426565 

60 

Model Years Chassis No./ Commencing 

Built VIN Prefix Chassis No./VIN 

Mini Mayfair (1000) Europe Non Catalyst 1988-92 X-L2S1S 396449 

Mini Mayfair (1000) Europe Catalyst 1989-92 X-L2S3S 426565 

Mini Sprite (1275) 1992-94 XN-YA 049349 

Mini Sprite 1.3i (1275) 1994-96 XN-YA 058254 

Mini Mayfair (1275) 1992-94 XN-WA 049349 

Mini Mayfair 1.3i (1275) 1994-96 XN-WA 058254 

Mini Cooper (1275) RSP Limited Edition 1990 XN-CA 010001 

Mini Cooper (1275) 1990-91 XN-CA 011651 

Mini Cooper 1.3i (1275) 1991-96 XN-CA 031550 

Mini Saloons 1997 On (Multi Point Injection or MPi, plus TBi) 

Mini (1275) MPi 1997-2000 XN-WA 134455 

Mini (1275) TBi Japan 1997-1999 XN-WA 134455 

Mini Cooper (1275) MPi 1997-2000 XN-CA 134455 

Mini Cooper (1275) TBi Japan 1997-1999 XN-CA 134455 

Riley and Wolseley Saloons 1961-69 

Riley Elf (850) 1961-63 R-A2S1 156851 

Riley Elf Mk II (1000) 1963-66 R-A2S2 369601 

Riley Elf Mk III (1000) 1966-69 R-A2S3 930221 

Wolsele y Hornet (850) 1961-63 W-A2S1 156861 

Wolsele y Hornet Mk II (1000) 1963-66 W-A2S2 367151 

Wolsele y Hornet Mk III (1000) 1966-69 W-A2S3 927473 

Mini Clubman Saloons 1969-80 

Mini Clubman (1000) 1969-74 X-A2S2 101 

Mini Clubman (1000) 1974-75 X-L2S2 101 

Mini Clubman (1100) 1975-80 X-C2S2 258877 

Mini Clubman (1000 Automatic) 1975-80 X-L2S2 258877 

Mini 1275 GT 1969-74 X-AD2 101 

Mini 1275 GT 1974-80 X-E2D2 101 

Mini Cabriolets 1991-96 

Mini Cabriolet (Lamm Design) 1991-93 XN-WB 024857 

Mini Cabriolet (Rover) 1993-96 XN-WB 061481 

Austin and Morris Mk I Estates 1960-67 

Austin Seven Countryman (850) 1960-62 A-AW7 19126 

Austin Mini Countryman (850) 1962-67 A-AW7 197104 

Morris Mini Minor Traveller (850) 1960-67 M-AW4 19101 

Austin and Morris Mk II Estates 1967-69 

Austin Mini Countryman Mk II 1000 1967-69 A-AWB 1068101 

Morris Mini Traveller Mk II 1000 1967-69 M-AW6 1068401 

Mini Clubman and HL Estates 1969-82 

Mini Clubman Estate (1000) 1969-74 X-A2W2 101 

Mini Clubman Estate (1000) 1974-75 X-L2W2 101 

Mini Clubman Estate (1100) 1975-80 X-C2W2 259639 

Mini Clubman Estate (1000 Automatic) 1975-80 X-L2W2 259639 

Mini HL Estate (1000) 1980-82 X-L2W2 751080 

Mini Vans 1960-84 

Austin Seven/Mini Van (850) 1960-69 A-AV7 12101 

Austin Mini Van (1000) 1967-69 A-AV7 1068001 

Morris Mini Van (850) 1960-69 M-AV4 12601 

Morris Mini Van (1000) 1967-69 M-AV4 1068001 

Mini Van (850 and 1000) 1969-74 X-AV1 101 

Mini Van (850) 1974-79 X-KV1 101 

Mini Van (1000) 1974-79 X-LV1 101 

Mini 95 Van (850) 1979-84 X-KV1 126932 

Mini 95 Van (1000) 1979-84 X-LV1 126932 

Mini Pick Ups 1961-83 

Austin Seven/Mini Pick Up (850) 1961-69 A-AU7 87551 

Austin Mini Pick Up (1000) 1967-69 A-AU7 1068001 

Morris Mini Pick Up (850) 1961-69 M-AU4 91551 

Morris Mini Pick Up (1000) 1967-69 M-AU4 1068001 

Mini Pick Up (850 and 1000) 1969-74 X-AU1 101 

Mini Pick Up (850) 1974-79 X-KU1 101 

Mini Pick Up (1000) 1974-79 X-LU1 101 

Mini 95 Pick Up (850) 1979-80 X-KU1 25448 

Mini 95 Pick Up (1000) 1979-83 X-LU1 25448

Somerford Mini Ltd. Ordering Parts Using This Catalogue

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