Next to established patterns adopted by the majority of manufacturers, there have been others that have affected the valves and their control systems and recall. Some were valid, but were too expensive or were not advantageous under the aspect of constructive or functional. Others were perhaps too imaginative…
In engines with combustion chambers hemispherical , or roof of the valves, inclined, and are cross-cutting. From one side of the head there are those of aspiration, and the other the exhaust. Some, however, did not want to adopt this solution, the most logical and widely standardized. Have been proposed heads with four valves arranged radially, but in the automotive field have not been taken in the production of the series, and have had a considerable use in some engines single cylinder for motorcycle. Has had wide use on the cars of a famous manufacturer to another schema, that provides for the arrangement of the two valves inclined to each cylinder in a transverse plane, i.e. parallel to the axis of the crankshaft. The house of which we are speaking is the Lancia that has used this constructive solution on models such as the Ardea, with single over-head camshaft, the Aurelia and the Flaminia (both with the engine six-cylinder V 60°), and the Flavia, built since 1960 to 1971. This vehicle, the first front-wheel drive of the house of turin, was equipped with a four-cylinder engine opposing entirely of aluminum alloy and the distribution to the rods and rocker arms driven by two cam shafts placed in the crankcase. The latter was in two symmetrical parts (each of which incorporated a bank of cylinders) that were included in the group according to a vertical longitudinal plane. The cylinder bores were reported in the wet, with the flange of the lower support surface. The engine of the Flavia was built in displacements ranging from 1.5 to 2 liters.
To invoke the valves are usually coil springs, are available today in multiple versions. Are extremely common of those cylindrical, variable pitch but are finding a number of applications, increasing those of the type called Beehive, which is truncated in the part opposite to the end support. This lets you reduce the moving mass of the spring and use a spring of smaller dimensions and therefore lighter. To equal the acceleration of the valve and with the same maximum speed of rotation is then possible to use springs with a lower load, which is advantageous as it reduces the friction losses in the overall distribution, what is advantageous for the purposes of the containment of the consumption.
Another type of spring, which in the past has had wide use in engines for motorcycles, but the car has been used only rarely, is the needle, with the thread that works, not in torsion, but bending. Have used springs of this kind, only some of the competition engines of the Fifties as some Ferrari and Maserati (V8 and V12, then also used by Cooper in 1966) and the quadricilindrici Vanwall and BRM Formula One.
Very interesting are the springs to the torsion bar, which in the automotive industry have tied their name to the Panhard post-war. These cars, manufactured up to 1965, were equipped with an engine with two opposed pistons of great technical sophistication. Air-cooled, had a crankshaft of composite and main bearings and connecting rod rolling. Each head was cast in block with the corresponding cylinder; the cast iron liner was installed with an interference fit. For the recall of the valves employed, as said torsion bars housed in special cases tubular that flowed out from the heads. Their arrangement is changed in the second (and more performant) version of the engine.
The Honda has devoted considerable attention to the torsion bar in the mid-Sixties. Adopted on the motion-twin CB 450, which was produced until 1974 (to then become in the CB 500 T), and has had a remarkable diffusion in Italy. Regarding the cars, he used in 1968, not on a set pattern but on two of his engines of Formula One (12-and 8-cylinder engines).
The torsion bars have been employed to retrieve the valves in the engine, Butterworth built in the second half of the Fifties. It was a four-cylinder opposed, 1.5 litre, air-cooled, has come to deliver approximately 150 horsepower at 7000 rpm. The salient feature of this interesting quadricilindrico was not constituted, however, by the adoption of the torsion bars but the type of valves used. Those of aspiration, in fact, not flowing down along the guides installed in the head, but swung!
The valves in question were made in the second half of the Fifties by Archie Butterworth, a technical creative irish. Were initially tested on a single-cylinder motorcycle, and later were installed on the quadricilindrico boxer 1500, which has been mounted on a race car and has also been used in a race.
These valves swing, used only in the aspiration, were born in two parts, what that allowed you to do the grinding. Then it is passed to the solution in one piece, for obvious reasons of lightness and fairing aerodynamics.
At Butterworth, you must also have a sequential gearbox in which the principle of operation was similar to that of changes in the cruise sliding. In this case, however, the scroll was the tree itself, which of course was tubular. This device is liked very much to Colin Chapman, who valued in particular the low weight and the speed of the connection. This has led him to build one of a similar type to his first Lotus race.