The Seal - E T Westbury
One can imagine the stir this engine caused when it was released in 1947! Westbury, in his efficient manner, was at pains to explain the practical virtues of a multi-cylinder layout for scale cruisers and launches up to around 4ft long. "Reduced height... a more realistic marine installation..." 'Practical' be damned; this engine promised constructors an end to the swingeing austerity of WW2. During a period when less than 5% of UK households owned a car, to build and run an engine that was every bit as sophisticated as the real thing, was the answer to a maiden's prayer! 70 years on (with 5% of UK households owning 3 or more cars!) building and running the Seal offers no less satisfaction to the constructor.
The layout of the Seal owes a lot to pre-war automotive design, using side valves and a two bearing crank to reduce complexity. The combined inlet and exhaust manifold casting is a brave and successful touch, as is the HT distributor assembly. A carburettor design with automatic mixture compensation is provided and can be fitted in an up-draught or down-draught attitude.
The 10 castings for the Seal are aluminium, keeping the weight of the engine to a minimum. The crankshaft, perhaps the most demanding component, is cut from flat steel bar and has a stoke of 11/16". With a bore of Ø5/8", the swept capacity of the Seal is actually 13.8cc, rather than 15cc which is often quoted. The engine block measures 3" x 3" x 4" (H x W x L).
The Seal is known as a good starter (how could it fail with 2 sparks per revolution?) and a very flexible runner. The Seal is also known as a "rites of passage" project that each must face before being dubbed a "craftsman". To help constructors along their quest however, the build notes are highly detailed, the castings are well proven and the finished product is a valuable and renowned classic.
The Seal in Action