New 70 b.h.p. Engine for Thames Chassis
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1-1 A NEW four-cylindered overhead
valve petrol engine which develops 70 b.h.p. at 2,800 r.p.m., has been introduced by the Ford Motor Co., Ltd. It is intended for fitting into Thames 2-ton and 3-ton chassis. With a capacity of 3.610 c.c., it delivers maximum torque of 165 lb.-ft. at 1,500 r.p.m. The bore is 3.937 in. (100 mm.) and the stroke 4.53 in. (115 mm.), the R.A.C. rating being 24.8 h.p.
The cylinder block, flywheel housing • and the uppet half of the crankcase form an integral casting in iron. The wet-type cylinder liners are positively located at the top and bottom and are easily replaceable. They are water jacketed for their full length.
An alloy-steel crankshaft is supported in five steel-backed lead-indium-faced bearings of 2.99 in. diameter. These hearings, in conjunction with the bigend and camshaft bearings, are pressurelubricated by a gear-type pump driven by skew gear on an auxiliary drive shaft.
Plated lead-indium steel-backed shell bearings are fitted in the big-ends of the connecting rods, the small ends of which are bronze-bushed.
The aluminium-alloy tin-plated pistons have fully floating pins of 1.249 in. diameter. There are three compression rings above the pin, and two oilcontrol rings, one above and one below the pin. A gear-driven camshaft, mounted on five 2.059 in. diameter bearings, operates the valves through
hollow stemmed mushroom ended tappets.
Mushroom ends are also provided on the push-rods: adjustment for clearance is by a screw and lock-nut on the rocker arms. The arms are lubricated by pressure through the hollow rocker shaft, which is supported on five brackets, Holes drilled in the rockers provide for the lubrication of the wiping faces.
Replaceable inserts of molybdenumchrome-alloy steel: are used for the exhaust-valve seats. All the valves are inclined at an angle of 30 degrees.
The Zenith downdratight carburetter has a light-alloy intake manifold of the Siamesed two-port type. It is bolted to the four-port cast-iron exhaust manifold and to the cylinder head, which has wedge-shaped combustion chambers.
Fuel is delivered by a camshaftoperated diaphragm pump incorporating a full-flow filter. The air cleaner is an AC Sphinx unit.
The cooling system incorporates a belt-driven, vane-type pump mounted behind the 18-in.-diameter four-bladed fan. A single belt drives the fan, water pump and 12-volt generator.
Capacity of the radiator is l gat. and of the complete system 31 gal. A thermostat is fitted in the water-outlet flange in the cylinder head. The Ford company claim that they are the only makers in quantity production to design an engine specifically for 2-3-ton vehicles.