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).
Comparison of American engine design practices with existing company methods.
| Identifier | ExFiles\Box 173\3\ img091 | |
| Date | 4th April 1934 | |
| -6- The practice of passing oil directly from the connecting rod big end to the cylinder walls either by a hole through the rod or grooves in the rod bearing has become almost universal. The object is to provide lubrication for cold starting, oil consumption apparently being controlled by the rings. This arrangement seems to be much simpler than our existing extra oil scheme on the Phantom. Piston rings are being made deeper than is our present practice; to take care of the resultant higher stresses a better quality material is employed. A very ingenious means of checking the rings for uniform radial pressure has been adopted. There seems to be a difference of opinion as to the use of interference fits between the fully floating wrist pin and the piston, this point requires further experimental investigation. The thermostatically controlled hot spot is very widely used, in order to get a simple arrangement the induction pipe is almost invariably placed on the same side of the cylinder head as the exhaust manifold. The use of aluminium for crankcases is still exceedingly limited. Though this is mainly due to the strangle hold which the Aluminium Co. of America hold upon the production of the material, there is still a feeling that cast-iron is superior to aluminium in suppressing noise and vibrations. It would seem, therefore, that we could with advantage try the mono-block castings of our new designs in both materials to determine the true facts for ourselves. Generally speaking, American engineers seem to have reduced weight everywhere in the chassis except in the power plant. It seems to be accepted American practice that to get satisfactory slow running zero overlap should be used measured with .020 tappet clearance. This conforms fairly closely with our existing practice on the 20/25. | ||