Four-cylinder indirect injection overhead valve unit, 3.0 in. (76.2 mm.) bore by 3.5 in (88.9 mm.) stroke, has a capacity of 1,621 c.c. (99 cu. in.) and developes a gross b.h.p. of 42.3 at 3,600 r.p.m. and 71 lb. ft. (9.82 kg. m.) torque at 2,250 r.p.m. The unit type cast iron CYLINDER BLOCK and CRANKCASE carries cast iron wet liners with full-length water jackets. The CRANKSHAFT is forged from chrome molybdenum steel with three main journals supported in steel-backed copper lead indium bearing shells. The CRANKPIN bearings are of the steel-backed lead bronze shell type, and the high tensile steel CONNECTING RODS have small-end bushes of the wrapped lead bronze steel-backed type. The PISTONS are made from high silicon aluminium alloy and have three compression rings and one scraper ring above the fully-floating gudgeon pin, and one scraper ring below it. The cast iron CAMSHAFT is situated low on the nearside of the engine and operates the valves through mushroom tappets, push rods and rocker levels. Both camshaft and fuel injection pump are driven via an idler gear from the crankshaft, all gears having helical teeth. Efficient LUBRICATION is assured by a 'Hobourn-Eaton' pump whilst a full-flow filter mounted on the off-side of the engine ensures a supply of clean lubricant from the 6 Imperial pint (3.41 litr) oil sump. The fuel INJECTION PUMP is a 'C.A.V.' DPA distributor type which incorporates a hydraulic governor and an automatic advance and retard mechanism. The fuel system includes a paper element filter and injection is by pintle type nozzles which are flange mounted.
Adequate COOLING is ensured by a belt-driven water pump, and in conjunction with a four-bladed fan ensures vigorous air and water circulation through the robust radiator core. A 'by-pass' thermostat is fitted to regulate engine heat, whilst a 'C.A.V.' "Thermostat" COLD STARTING AID ensures easy starting under adverse conditions.