New Perkins "Flat" Engine
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A NEW power unit with a distributor("A type fuel-injection pump will be exhibited on the Perkins stand at Earls Court. It is the C.305 six-cylindered indirect-injection engine, which has been developed in conjunction with Commer Cars, Ltd., for use in the 4-, 5-, and 6-ton chassis, described on pages 232-234, and in the Karrier Gamecock 3-4-toner.
It has been designed to operate at an angle of 24° from the horizontal, this being its location in the Commer chassis. Its nearest vertical equivalent is the P6 (V), but whereas the P6 has a bore of 88.9 mm. (3.5 in.), the C.305 has a 91.94 mm. (3.6 in.) bore, the 127 mm. stroke being the same as that for the P6. 'Cubic capacity of the new engine is 5 litres (305.3 Cu. in.).
It is rated to develop 87 b.h.p. gross (79.5 b.h.p. net) at 2,400 r.p.m., whilst the gross torque output is 216 lb.-ft. at 1,300 r.p.m. The nct torque is 208 lb.-ft. The compression ratio is 17.4 to 1.
A One-piece cylinder block and crankcase casting is employed, and the cylinder bores are fitted with renewable full-length thin-wall chromium-plated liners. The one-piece cylinder head has inlet valves of B.S.970 EN.18S 1 per cent. chromium steel, whilst the exhaust valves are of B.S.970 EN.52 silicon-chromium steel.
A chain is employed for the camshaft and auxiliary drives, and an automatic tensioner is incorporated. The auxiliary drive shaft, on the upper side of the engine, drives the lubricating-oil pump, the fuel-lift pump, the fuel-injection pump and the exhauster.
The high silicon aluminium alloy pistons carry three compression rings and two scraper rings, the second and third compression rings being taper-faced. The • gudgeon pins are fully floating. The big ends, are split at right angles to the connecting-rod axis and carry prefinished steel-backed, copper-lead-lined bearings. Similar bearing material is employed for the crankshaft, which has seven bearings and is a chromemolybdenum-steel forging.
An eccentric lobe-type oil pump is driven by skew gearing from the auxiliary drive shaft. Timing-gear lubrication is by splash from the camshaft bearings. The lubricating-oil filter has a paper element and incorporates a by-pass relief valve. The oil filler tube is connected to an open breather pipe.
A C.A.V. fuel-injection pump is driven in line with the exhauster, the drive passing through the exhauster first. The pump incorporates a built-in hydraulic governor, and the fuel injectors are of the two-hole type. For cold starting, •a Thermostart 12v. heater is fitted into the induction manifold inlet bend.
The Perkins C.305 in dry condition weighs 831 lb., less starter motor and fuel filter. Measured from the front of the crankshaft pulley extension to the rear of the flywheel housing, it is 371 in. long, whilst its width and height are 34 in. and 28i in., respectively.