Cylinder Head - 848 and 997cc No. Part No. Description Qty. Remarks No. Part No. Description Qty. Remarks 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 55 LWZ205 WASHER, locking 4 1959-74. 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 <strong>Somerford</strong> <strong>Mini</strong> 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 <strong>Somerford</strong> <strong>Mini</strong> 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 <strong>Somerford</strong> <strong>Mini</strong>; 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. 90 AEA311 SPRING, valve 8 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. 93 88G616 CAP, upper, valve spring 8 94 2A879 OIL SEAL, valve stem 8 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 98 AEA311 SPRING, valve 8 99 88G459 SPLIT COLLET, pair, valve retaining 8 100 88G616 CAP, upper, valve spring 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) 102 CAM6502 VALVE, inlet, 1 1/16" (27mm) dia. 4 103 CAM6503 VALVE, exhaust, 1" (25.4mm) dia. 4 CAM6505 VALVE, exhaust, 1" (25.4mm) dia., 4 Lead free (chrome stem). 104 AEA311 SPRING, valve 8 105 88G459 SPLIT COLLET, pair, valve retaining 8 106 88G616 CAP, upper, valve spring 8 107 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 . 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Cylinder Head - 998 and 1098cc © Copyright <strong>Somerford</strong> <strong>Mini</strong> Limited 38 Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk