The trend of design
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Sir,
I would like to disagree with a couple of points raised in your January editorial. You said the eight cylinder engine has only survived in “V” formation—do not Rolls Royce still produce the B80 straight-eight engine? I am sure they produce the B60 straight-six as our local fire brigade always use them in their new fire engines. Is the side-valve engine dead—no only half dead. It is still used for exhaust valves on the above engines as well as in the old P3/P4/P5 Rover engine used in the Land Rover, which in station wagon or caravan form are part of the car market. Are push-rods on the way out—I doubt it. Push-rods for all their technical deficiencies are a durable form of valve operation and ideal for mere mundane form of transport. Servicing is simple, wear minimal and overhaul normally straightforward. Overhead cams may be technically superior and the cogged belt simple but if, the belt slips or breaks the results can be catastrophic. Servicing is not so simple and wear can he a problem. On the Ford Pinto engine it takes ages to remove the rocker cover and the valves are difficult to adjust. Moreover, as Rovers found twenty odd years ago, if you have a cam scraping against the pad of a pivoted cam follower it doesn’t last very long. The Pinto engine eats camshafts and followers for a pastime. You take the view that overdrives are too often provided to mask poorly-chosen gear ratios and five-speed gearboxes are the answer. Surely the opposite ‘is also true—five-speed gearboxes employed when a manufacturer tries to cut the cost of employing the superior overdrive. All the five-speed box generally does is to provide an “overdrive top” gear, and a one that has to be manually engaged and disengaged to boot. An overdrive can be engaged or disengaged at a flick of a switch and on manual boxes can provide an extra gear between 3rd and 4th. Also at least one knows which gear one is in which is always a problem to decide on five-speed gearboxes.
Wellington R. M. Stenning
[I was writing of engines in production cars and by side-valves implied the L-head sideby-side valve engine, not those of i.o.c. formation.—Ed.]