The A-series and A+ engines fitted to the Classic Mini share a common architecture across all capacities, 848cc, 998cc, 1098cc and 1275cc, but the internal components differ between engine sizes, between A-series and A+ specifications, and across production dates. Before ordering any engine internal component, you need to know three things: the engine capacity, whether the engine is A-series or A+ (smooth block vs ribbed block), and in many cases the approximate production date. Getting any of these wrong will result in components that do not fit.
Crankshafts and Bearings
Crankshafts are available new and reground for all engine sizes. Main bearing specifications changed across production but the change point varies by engine. The 848cc and 1098cc use offset locating lip bearings throughout. The 998cc used offset locating lip bearings up to 1983, with a change to centre lower locating lip bearings (alongside a crankshaft revision) from 1983 to 1991, both pre-A+ and the early A+ 998cc 1980 to 1983 use the offset bearings.
The 1275cc used offset bearings on the pre-A+ and early A+ engines up to 1980, and centre lower locating lip bearings on all 1990 to 2000 reintroduction-era 1275cc A+ engines. The two bearing types are not interchangeable and must be matched to the crankshaft and block. Main bearing sets and big end bearing sets are available in standard and a range of oversize specifications for reground crankshafts.
Crankshaft Pulleys and Timing Components
The crankshaft pulley specification differs between engine sizes and between pre-A+ and A+ engines. The 848cc and 998cc engines use a simple pulley, while the 1098cc and 1275cc use a pulley and damper assembly. MPi models from 1997 use a polyvee belt-driven pulley that differs from all earlier types. The timing chain, camshaft gear, tensioner pad, tensioner plate and timing cover all changed across production.
The timing cover itself comes in several variants, pre-A+ without tensioner (up to 1979), pre-A+ with tensioner (1979 to 1980), A+ with tensioner (1980 onwards), and specific variants for SPi (1991 to 1996) and MPi (1997 to 2000) engines.
Oil Pumps
Three oil pump drive types were used across production: pin drive, slot drive and star drive, depending on engine size, date and whether the car is manual or automatic. The oil pump drive type must match the camshaft, and fitting the wrong pump to the wrong camshaft will result in no oil pressure. High-capacity oil pumps are available as an upgrade for cars used in more demanding applications.
Camshafts and Cam Followers
The camshaft is driven by the timing chain and operates the valves via push rods and rocker arms. Cam followers (tappets) are available for all engine variants, with the MPi engine from 1997 onwards using a specific cam follower type. The camshaft bearing set differs between manual and automatic gearbox engines.
Gasket Sets
Complete gasket sets are available for all engine sizes in both A-series and A+ specifications. Head gaskets, timing cover gaskets, sump gaskets, rocker cover gaskets and all ancillary seals are also available individually. The head gasket for the conversion from leaded to unleaded fuel specification is available as a standalone item.
MGOC Spares Range
The MGOC Spares Classic Mini engine components range covers crankshafts (new and reground), main bearing sets and big end bearing sets in standard and oversize, thrust washers, crankshaft pulleys and damper assemblies, Woodruff keys, oil throwers, pistons and piston ring sets, con rods, gudgeon pins, camshafts, cam followers, camshaft bearing sets, timing chains, camshaft gears, timing chain tensioner pads and plates, timing covers for all variants (pre-A+, A+, SPi, MPi), timing cover oil seals and gaskets, oil pumps in standard and high-capacity specifications, mounting plates, complete engine gasket sets and individual gaskets for all engine sizes.