DORMAN Engine PROGRESS r - r ESTIMONY to the soundness of
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design and workmanship of the
engines produced by W. H. Dorman and Co., Ltd., Stafford, is implied when we announce that the comprehensive range of petrol power units is to be continued unchanged for 1932. A recent addition takes the form of a new type of six-cylindered engine, made in two sizes. The 6 J.U, has bore and stroke dimensions of 95 mm. and 140 mm. respectively, and develops 95 b.h.p. at 2,400 r.p.m. The 6 J.U.L. has corresponding figures of 100 mm., 140 mm., and 105 b.h.p.
As these engines are of similar design they may conveniently be described together. The smaller model has a piston-swept volume of 5,954 c.c., and the larger a capacity of 6,597 c.c. Aluminium is used for the castings for the sump and crankcase, and the joint between them is made secure by the use of studs ; the oil carried totals 4 gallons.
A good feature of the design is that the junetion of these castings occurs 4 ins, below the centre line of the fourbearing crankshaft, thus ensuring rigidity of the assembly. The main bearings are in gunmetal with white metal linings; at the front end of the crankshaft is a vibration damper.
Surmounting the crankcase is a monobloc iron casting comprising the six cylinder bores and the large water jackets. It is worthy of note that the water inlet causes the cooling medium to be well distributed.
All the valves are mounted in the near side of the block, the tappets and springs being concealed by quickly detachable covers. For the inlet valves 3-per-cent niekel steel is employed, whilst silchrome steel is the material adopted for the exhaust valves. . .
Helical gears form the distribution drive for the camshaft, which rotates in four bearings. On the extreme lefthand side of the engine is a shaft whieh drives the dynamo at its rear and the fan-belt pulley at the front. Above the casing for this shaft is the lateral and inclined platform for the magneto, whilst the water pump balances the cross-shaft on the off side.
With the exception of the water pump, there are no auxiliaries on the
off side, so that this engine is especially suited to mounting 171 a for
ward-control chassis. •
At the rear end on the near side is another group of auxiliaries ; this consists of the starter, passing through a tunnel in the crankcase, the oil filler and the oil filter, the last-named being placed at a high level so as to he. easily reached above the chassis frame. Adjacent to the filter is the dipstick, which has, as a completrient, an oil-level tap.
Two two-bolt dogs are employed to locate the twin exhaust branches; this splitting-up of the gas stream enables more conveniently sized passages to he employed, minimizes interference and enables joint making to be more easily effected after overhaul. A downward projection from the front branch makes contact with the square-section inlet tract, thus providing the desired hotspot effect, which is so essential when using commercial grades of spirit. A. Selex horizontal carburetter is directly attached to the inlet manifold.
Capping the engine is a rnonobloe detachable cylinder head, this providing combustion chambers of the turbulent type. The water outlet consists of a front port with horizontal face.
Either the large or small engine of this design can be supplied for unit or non-unit mounting,
Of the large range of Dorman petrol and compression-ignition engines, of R.A.C. ratings from 10.5 h.p. to 53.6 h.p., it is intended to display five examples at Olympia ; one of them will be the 6 J.U.L. described above whilst the other four will be four-cylindered. units of -70 b.h.p., 50 b.h.p., 45 h.h.p. and 37 b.h.p.