Griffon's much larger capacity. This redesigned engine first ran on 26 June 1940 and went into production as the Griffon II. In early 1940, with the expected Battle of Britain looming, on the orders of Lord Beaverbrook, Minister of Aircraft Production, work on the new engine had been halted temporarily to concentrate on the smaller 27 L () Merlin which had already surpassed the output achieved with the early Griffon. Design Compared with earlier Rolls-Royce designs, the Griffon engine featured several improvements, which meant that it was physically only slightly larger than the Merlin, in spite of its 36% larger capacity of 37-litres (2,240 cu in). One significant difference was the incorporation of the camshaft and magneto drives into the propeller reduction gears at the front of the engine, rather than using a separate system of gears driven from the back end of the crankshaft; this allowed the overall length of the engine to be reduced as well as making the drive train more reliable and efficient. The drive for the supercharger was also taken off the front of the engine, which had required a long shaft to run to its location at the back of the engine. The Merlin engine's crankshaft lubrication was via a gallery cut into the engine block to feed each main bearing and then onto a secondary adjacent big end bearing via a gallery in the crankshaft itself. The crankpin was second in line to the main bearing in oil flow and pressure, with oil having to flow through the main bearing first. The Griffon improved on this arrangement being the first Rolls-Royce production aero engine to use a hollow crankshaft as the means of lubricating the main and big end bearings, with oil being fed from each end of the crankshaft giving even flow to all bearings. In another change from convention, one high efficiency B.T.H-manufactured dual magneto was mounted on top of the propeller reduction casing; earlier Rolls-Royce designs using twin magnetos mounted at the rear of the engine. The Griffon 61 series introduced a two-stage supercharger and other design changes: the pressure oil pumps were now housed internally within the sump and an effort was made to remove as many external pipes as possible. In addition, the drive for the supercharger was moved to the crankshaft at the back of the engine, via a short torsion shaft, rather than at the front