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 casting techniques for crankcases and cylinder blocks, comparing different engine designs.
| Identifier | ExFiles\Box 142\4\ scan0046 | |
| Date | 26th November 1936 guessed | |
| (Sheet 3) water space between, the minimum desirable figure for the thickness of the jacket core is said to be .375" which is about .1 more than we use on the Merlin and Kestrel. Where a core joint occurs, as it usually does, in such places it is recommended that the two halves of the core where they abut are not rubbed to form a flush joint, but are allowed to overlap if they do not quite match. (8) In connection with large castings such as crankcases in general, it is considered undesirable to have any water or oil ways. Where drilled oil passages are used however it is recommended that the boss be made 1/16" larger in diameter than normal to allow for tubing if required. Porosity in oil feed bosses can be largely overcome by chilling, but a 100% result can never be guaranteed where a boss is required to carry a drilling under pressure it is considered excusable to resort to tubing. The foundry people would much sooner avoid such bosses altogether. (9) With regard to integral construction of cylinder blocks and crankcase, Mr Raby saw no difficulty in this if carried out with a removable liner construction so that no separate jacket cores are required. In the case of a cast iron scheme in which the crankcase cylinder barrels and jackets were all in one piece, as on the new Lagonda, he was of the opinion that this was entirely impractical, although he qualified this by saying that his interest was confined to the aluminium foundry. With regard to the 25/30 and Bentley cylinder blocks, he was of the opinion that the distance between the bores of .650, which allows for a jacket thickness between barrels of .325 was not sufficiently practical. In connection with this last point we know that the Buick engine is made with a distance of .650, with a water space of .2. E.{Mr Elliott - Chief Engineer} | ||