Somerford Mini Ltd. Ordering Parts Using This Catalogue

Internal Engine - 848 and 997cc 

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

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 

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 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. 

Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk 19

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Somerford Mini Ltd. Ordering Parts Using This Catalogue

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