Somerford Mini Ltd. Ordering Parts Using This Catalogue

Cylinder Head - 848 and 997cc
No. Part No. Description Qty. Remarks No. Part No. Description Qty. Remarks
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
5 CAM150 STUD, cylinder head, long 4
6 CAM151 STUD, cylinder head, shor t 5
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
18 PWZ105 WASHER, plain 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
25 LWZ304 WASHER, locking 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
29 PWZ105 WASHER, plain 2
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.
Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk
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