Cylinder Head - 998 and 1098cc No. Part No. Description Qty. Remarks No. Part No. Description Qty. Remarks 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. 46 1B2925 DISTANCE PIECE 2 Original zinc finish. 12G687 DISTANCE PIECE 2 Alternative chrome finish. 47 1A2156 WASHER, cup 2 Original zinc finish. 12G679 WASHER, cup 2 Alternative chrome finish. 48 12A1358 BUSH, rubber 2 49 12A1968 LIFTING EYE, engine, temporary fitment 2 Fit only while lifting work is taking place. Rocker Shaft, Rockers and Fixings 50 12G1926 PEDESTAL, rocker shaft, with oil hole 3 51 12G1927 PEDESTAL, rocker shaft, with tapped hole 1 52 2A258 SCREW, locating rocker shaft 1 53 2A515 PLATE, securing screw 1 1963-74. 54 2A259 PLATE, securing screw 1 1974 on; will fit 1963-74 models. 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 58 LWZ205 WASHER, locking 4 1963-69. 59 PWZ105 WASHER, plain 3 1969 on. Not on tapped pedestal. 60 PWZ106 WASHER, plain 3 1969 on. Not on tapped pedestal. 61 AEG399 ROCKER SHAFT ASS’Y 1 1963-74. 62 12A1950 ROCKER SHAFT 1 1974 on; will fit 1963-74 models. 63 6K878 END PLUG , plain 1 Included in AEG399 rocker shaft ass’y. 64 2K4608 END PLUG, screwed 1 Included in AEG399 rocker shaft ass’y. 65 2A964 ROCKER, pressed steel 8 First rocker type. 66 12G1221 ROCKER, forged 8 Second 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 <strong>Somerford</strong> <strong>Mini</strong>; please contact us for details. 998cc (Not Cooper) 1963-74 approx Valves With 1/4" Collet Groove 83 2A877 VALVE, inlet, 1 1/16" (27mm) dia. 4 84 AEA434 VALVE, exhaust, 1" (25.4mm) dia. 4 85 AEA311 SPRING, valve 8 86 2A11 SPLIT COLLET, pair, valve retaining 8 87 2A12 CIRCLIP, valve collet 8 1963-69; no longer fitted. 88 88G616 CAP, upper, valve spring 8 89 2A879 OIL SEAL, valve stem 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. 96 2A12 CIRCLIP, valve collet 8 1963-69; no longer fitted. 97 88G616 CAP, upper, valve springs 8 98 AEA403 COLLAR, lower, valve springs 8 99 2A879 OIL SEAL, valve stem 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 <strong>Somerford</strong> 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 <strong>Somerford</strong> <strong>Mini</strong> for details of our range of engine tuning parts. 998cc 1974 approx. to 1981 Valves With 1/8" Collet Groove, 7/32" From Valve Tip 100 CAM6391 VALVE, inlet, 1 1/16" (27mm) dia. 4 101 12A1987 VALVE, exhaust, 1" (25.4mm) dia. 4 102 AEA311 SPRING, valve 8 103 88G459 SPLIT COLLET, pair, valve retaining 8 104 88G616 CAP, upper, valve spring 8 105 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. 70 12A1215 SCREW, tappet adjusting 8 Use with pressed steel rocker. 71 6K654 NUT, locking screw 8 Use with pressed steel rocker. 72 AEG167 SCREW, tappet adjusting 8 Use with forged rock er. 73 NT605061 NUT, locking screw 8 Use with forged rock er. 74 12H3376 SCREW, tappet adjusting 8 Use with scintered rocker. 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 78 6K555 WASHER, plain, 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. Valves and Valve Springs 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 Valves With 1/8" Collet Groove, 7/32" From Valve Tip 107 12G3036 VALVE, inlet, 1 5/32" (29.4mm) dia. 4 108 12A1987 VALVE, exhaust, 1" (25.4mm) dia. 4 109 12G4287 SPRING, valve 8 110 88G459 SPLIT COLLET, pair, valve retaining 8 111 88G616 CAP, upper, valve spring 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) 113 CAM6502 VALVE, inlet, 1 1/16" (27mm) dia. 4 114 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. 116 88G459 SPLIT COLLET, pair, valve retaining 8 117 88G617 CAP, upper, valve spring 8 118 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 Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk 41
Cylinder Head - 1275cc (Not Cooper S) © Copyright <strong>Somerford</strong> <strong>Mini</strong> Limited 42 Tel. 01249 721421 Fax. 01249 721316 www.somerford-mini.co.uk