From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Engine design choices, comparing components and practices with American manufacturers.
| Identifier | ExFiles\Box 174\2\ img124 | |
| Date | 3rd May 1937 guessed | |
| (2) ENGINES. Uniform degree of smoothness whether six, line eight, vee eight or twelve. Ford the exception. Side valve unit lighter and less costly than push rod but 5-10% down in performance. We should try a good American side valve unit in one of our cars. Push rod engines are gaining something by controlling combustion with un-symmetrical piston crowns. We should follow this up and see if we can get anything out of it. On bearings, areas have been stepped up and there is a general reversion to Babbit. Close clearances give a smoother engine. Bringing water down to the bottom of the cylinder bores is considered to be more important than having water between the bores. Offset big end bearings are no good. Four bearing crankshafts can give a smooth engine up to 4500 R.P.M. Engines are being designed with a bearing between each cylinder. Tin plated pistons are agreed to be good. Inserted valve seats give good results, but some people are getting away with silichrome valves and no inserts. Less lead in American petrol however than here. Anti-surge valve spring dampers preferred to differential oiling. Hydraulic tappets now established. Wilcox Rich cheaper and better than Cadillac eccentric. We should get a set on test for P.III. Tocco crank likely to be more economical to produce than nitro hardening. We should test one out. Crankshafts, flywheels, clutches and clutch centres should be balanced as a unit to 1/4 oz.ins. G.M. balancing machine recommended. Cylinders are being cast with 3/16 of water between the bores. Buicks, with cylinder iron of which we have particulars, are remarkably free from cylinder bore wear. The average American cast iron engine weighs little or no more per H.P. than our 25/30, in many cases less. The flexible flywheel has been brought to a production state by Cadillacs, but is held up over the Patent situation. We should complete our experiments. Should be a great asset in getting engine smoothness. | ||