A LITTLE BIT OF HISTORY
TI lb above illustration is of a high-speed submersible lifeboat engine. What is this doing in M0Tott SPortT ? The answer is that it has an interesting link with motor-racing history. In 1925 the late F. B. Halford, who subsequently became Chief Engine Designer to the de llayilland Engine Co.; having designed the 11.11.P. aeroengine during the 1914/18 war, evolved his own racing engine, an advanced 6-cylinder “-litre wet-liner unit of 63 / So mm. bore and stroke. The crankshaft ran in seven plain bearings, the mi.-rods were of forged duralumin with whitemetal big-ends, and two inclined oh. valves per cylinder were operated by twin o.h, camshafts driven by a train of spur gears at the back of the cylinder block, which, like the crankcase, was of light alloy. Finger-type tappet levers were interposed between cams and ■alve stems and clearance was adjusted by shims within the valve caps. Ignition was by two magnetos, mounted vertically, one driven from the rear of each camshaft, firing special 12-mm. K.L.G. plugs, two per cylinder.
This engine was built for Major Hafford by The Weyburn Engineering Co. Ltd., of Elstead, Surrey, then well known for lifeboat engines and today, besides building diesel engines, making camshafts for many famous car manufacturers. They used a lapped metal-to-metal joint between the cast-iron head and lightalloy block of this HaWord Special engine, this being a delicate aspect of the design.
Ha/ford installed the engine in an old Aston Martin chassis, endowing it with a Roots-type supercharger driven from the crankshaft, and clothing the car with a very pretty pale blue aseater racing body of conventional G.P. form. Apparently 96 b.h.p. was developed at 5,300 r.p.m. hut during 1926 the engine was considerably rebuilt, Tao b.h.p. being developed at 5,500 r.p.m. using a boost of ii lb./sq. in. The interesting thing was that Major Raiford intended to employ an exhaust-driven turbo Supercharger, as used in aeroengines, and although the Halford Special achieved its racing successes—which included winning the 90-mph. Short Handicap at the 1926 Whitsun Brooklands Meeting, and the too-mph. Long Handicap at the Summer Meeting, with a best lap at 109,94 m.p.h.—in Roots-blown form, there was controversy as to whether it ever ran experimentally with the turbo-supercharger and an inter-cooler below the sump. I evaded this question in my ” History of Brooklands Motor Course ” but raised it With de Havillands three years ago. I was informed by Mr. W. H. Arscott, the present Chief Designer, that the centrifugal blower
installation never got beyond rather disappointing bench tests, and that as raced the car had Roots blowers.
This lines up with the recollections of The Weyburn Engineering Co., who supplied the original engine to Major HaIford in unblown form and ran it light only on the bench at his request, no power readings being taken. Apparently it was installed and the car prepared at the Aircraft Disposals Co. factory at Croydon aerodrome.
Subsequently the engine Was adapted for lifeboat work, at first in twin-cam form, then with revised push-rod valve gear, as illustrated, to obviate the complication of servicing, and of setting rhe tappets of the racing engine. The first of these lifeboat engines, which were designated the Type AE6, was installed in a 35 ft. 6 in. lifeboat at I lythe in January 1930 and later that year this boat attended a Lifeboat Conference at Calais. A second engine went into a Berwick-on-Tweed lifeboat in February 1930, this boat making the passage from Cowes in very bad Weather. The first engine was in good condition when dismantled after Some 350 hours’ running, Hamilton Gordon supervised assembly at Elstead. In all, 27 of these engines were ordered, and 19 were in service by midt932, two experimental units. having completed type tests late in 1929. They developed 35 b.h.p. at 3,300 r.p.m. and retained the 7-bearing crankshaft and H-section fOrged duralumin con.-rods, KE965 valves and dual magnetos of the racing engine, although having a cast-iron crankcase.—W. B.