Internal engine - 848 and 997cc

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 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.

848cc
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
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.
	12A120030	PISTON SET, original 4 ring type	1	Set of 4, +0.030" oversize.
	12A120040	PISTON SET, original 4 ring type	1	Set of 4, +0.040" oversize.
	12A120060	PISTON SET, original 4 ring type	1	Set of 4, +0.060" 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.
	15037030	PISTON SET, replacement 5 ring type	1	Set of 4, +0.030" oversize.
	15037040	PISTON SET, replacement 5 ring type	1	Set of 4, +0.040" oversize.
	15037060	PISTON SET, replacement 5 ring type	1	Set of 4, +0.060" 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.
	BHM1161030	RING SET, for original 4 ring pistons	1	4 piston set, +0.030" oversize.
	BHM1161040	RING SET, for original 4 ring pistons	1	4 piston set, +0.040" oversize.
	BHM1161060	RING SET, for original 4 ring pistons	1	4 piston set, +0.060" 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.
	R8577030	RING SET, for replacement 5 ring pistons	1	4 piston set, +0.030" oversize.
	R8577040	RING SET, for replacement 5 ring pistons	1	4 piston set, +0.040" oversize.
	R8577060	RING SET, for replacement 5 ring pistons	1	4 piston set, +0.060" oversize.

997cc
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
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.
	12A212020	PISTON SET, original 4 ring type	1	Set of 4, 9:1 CR; +0.020" oversize.
	12A212030	PISTON SET, original 4 ring type	1	Set of 4, 9:1 CR; +0.030" oversize.
	12A212040	PISTON SET, original 4 ring type	1	Set of 4, 9:1 CR; +0.040" 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.
	12A406020	PISTON SET, original 4 ring type	1	Set of 4, 8.3:1 CR; +0.020" oversize.
	12A406030	PISTON SET, original 4 ring type	1	Set of 4, 8.3:1 CR; +0.030" oversize.
	12A406040	PISTON SET, original 4 ring type	1	Set of 4, 8.3:1 CR; +0.040" oversize.
4	12A214STD	RING SET, pistons	1	4 piston set, standard size.
	12A214010	RING SET, pistons	1	4 piston set, +0.010" oversize.
	12A214020	RING SET, pistons	1	4 piston set, +0.020" oversize.
	12A214030	RING SET, pistons	1	4 piston set, +0.030" oversize.
	12A214040	RING SET, pistons	1	4 piston set, +0.040" 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 many 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.
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
7	12A1626	ROD ASS'Y, connecting, nos 2 and 4	2
8	12A1627	ROD ASS'Y, connecting, nos 1 and 3	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
13	LWZ305	WASHER, locking	4
14	8G2198STD	BEARING SET, connecting rod ('big end bearings')	1	Set of 4 pairs, standard size.
	8G2198010	BEARING SET, connecting rod ('big end bearings')	1	Set of 4 pairs, 0.010" undersize.
	8G2198020	BEARING SET, connecting rod ('big end bearings')	1	Set of 4 pairs, 0.020" undersize.
	8G2198030	BEARING SET, connecting rod ('big end bearings')	1	Set of 4 pairs, 0.030" undersize.
	8G2198040	BEARING SET, connecting rod ('big end bearings')	1	Set of 4 pairs, 0.040" undersize.

Crankshaft
Crankshafts shown here are either assemblies (including main bearings, connecting rod bearings and thrust 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.
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
15	28G113	CRANKSHAFT ASS'Y, with bearings, oil-fed bush type, 1 3/8" tail diameter	1	848cc 1959-62. Stamped no. 22A62.
	28G179	CRANKSHAFT ASS'Y, with bearings, Deva bush type, 1 3/8" tail diameter	1	848cc 1962-63. Stamped no. 22A298.
	8G2734	CRANKSHAFT ASS'Y, with bearings, Deva bush type, 1 1/2" tail diameter	1	848cc 1963-84. Stamped no. 12A670.
	28G153	CRANKSHAFT ASS'Y, with bearings, oil-fed bush type, 1 3/8" tail diameter	1	997cc 1961-62. Stamped no. 12A375.
	28G178	CRANKSHAFT ASS'Y, with bearings, Deva bush type, 1 1/2" tail diameter	1	997cc 1962-63. Stamped no. 12A298.
16	22A62	CRANKSHAFT, bare, oil-fed bush type, 1 3/8" tail diameter	1	848cc 1959-62. Stamped no. 22A62.
	22A298	CRANKSHAFT, bare, Deva bush type, 1 3/8" tail diameter	1	848cc 1962-63. Stamped no. 22A298.
	12A670	CRANKSHAFT, bare, Deva bush type, 1 1/2" tail diameter	1	848cc 1963-84. Stamped no. 12A670.
	12A375	CRANKSHAFT, bare, oil-fed bush type, 1 3/8" tail diameter	1	997cc 1961-62. Stamped no. 12A375.
	12A298	CRANKSHAFT, bare, Deva bush type, 1 1/2" tail diameter	1	997cc 1962-63. Stamped no. 12A298.
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).
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
19	8G2177STD	BEARING SET, main bearings, set of 3 pairs	1	848cc 1959-69, std. size.
	8G2177010	BEARING SET, main bearings, set of 3 pairs	1	848cc 1959-69, 0.010" undersize.
	8G2177020	BEARING SET, main bearings, set of 3 pairs	1	848cc 1959-69, 0.020" undersize.
	8G2177030	BEARING SET, main bearings, set of 3 pairs	1	848cc 1959-69, 0.030" undersize.
	8G2177040	BEARING SET, main bearings, set of 3 pairs	1	848cc 1959-69, 0.040" undersize.
	8G2332STD	BEARING SET, main bearings, set of 3 pairs	1	848cc 1969 on, 997cc; std. size.
	8G2332010	BEARING SET, main bearings, set of 3 pairs	1	848cc 1969 on, 997cc; 0.010" undersize.
	8G2332020	BEARING SET, main bearings, set of 3 pairs	1	848cc 1969 on, 997cc; 0.020" undersize.
	8G2332030	BEARING SET, main bearings, set of 3 pairs	1	848cc 1969 on, 997cc; 0.030" undersize.
	8G2332040	BEARING SET, main bearings, set of 3 pairs	1	848cc 1969 on, 997cc; 0.040" undersize.

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.
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
20	BHM1291STD	THRUST WASHERS, crankshaft, pair	A/R	848cc, standard size.
	BHM1291003	THRUST WASHERS, crankshaft, pair	A/R	848cc, +0.003" oversize.
	BHM1291030	THRUST WASHERS, crankshaft, pair	A/R	848cc, +0.030" oversize.
	BHM1292STD	THRUST WASHERS, crankshaft, pair	A/R	997cc, standard size.
	BHM1292003	THRUST WASHERS, crankshaft, pair	A/R	997cc, +0.003" oversize.
	BHM1292030	THRUST WASHERS, crankshaft, pair	A/R	997cc, +0.030" oversize.
21	6K836	KEY, Woodruff, 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 cover 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 for many years. If you want the original pulley, 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 '85H' 848cc engines from 1980 approximately onwards
received a pulley with a strobe timing plate attached as part of the A Plus modification programme.

848cc Crankshaft Pulley
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
26	2A940	PULLEY, crankshaft	1	1959-70, dynamo fitted models.
	12A1380	PULLEY, crankshaft	1	1959-70, alternator 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

997cc Crankshaft Pulley
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
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 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.
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
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 (flange also known as 'spider')	1	Use with 'star drive' type camshaft.
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.

Timing Chain
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
44	3H2127	CHAIN, timing	1
45	2A85	GEAR, timing chain, camshaft, with ring tensioners	1	1959-74, may be replaced by 12G4337 without ring tensioners.
46	2A86	GEAR, timing chain, camshaft, ring tensioner type	1	1959-74, may be replaced by 12G4337 without ring tensioners.
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, Woodruff	1
56	6K629	NUT, gear to camshaft	1
57	2A759	LOCK TAB, nut	1

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Internal engine - 848 and 997cc

TIMING CHAIN-SIMPLEX-IWIS HEAVY DUTY

KEY-WOODRUFF-TIMING GEAR TO CAMSHAFT

RING SET-5 RING PISTONS-850cc STD. SIZE

RING SET-5 RING PISTONS-850cc +060''

RING SET-5 RING PISTONS-850cc +040''

RING SET-5 RING PISTONS-850cc +030''

RING SET-5 RING PISTONS-850cc +020''

FLANGE-DRIVING-STAR DRIVE OIL PUMPS

PULLEY-CRANKSHAFT-850 & 998cc'80 ON A+ WITH TIMING PLATE

PULLEY-CRANKSHAFT-'70-'80 850 & 998cc

CAMSHAFT-850 & HIGH COMPRESSION 998cc-SLOT DRIVE-MANUAL-A+

USE: BEB088

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