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).
Letter to The Light Production Co. Ltd. regarding modifications to raised crown pistons.
| Identifier | ExFiles\Box 148\1\ scan0015 | |
| Date | 1st December 1938 | |
| 1256 EXPERIMENTAL DEPARTMENT. Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}9/JH. 1st. December, 1938. The Light Production Co.Ltd., 60/66 Rochester Row, WESTMINSTER. LONDON.S.W.1. For the attention of Mr. Brooks. Dear Sirs, In answer to your letter dated 29th. November, and further to ours of 26th. November. In view of the fact that you will have to make a new core box, to produce the .440 raised crown pistons, we would like to take advantage of this by including a further alteration. We enclose a print of Rm.{William Robotham - Chief Engineer}522 which shows the first stage of raised crown. We now wish to remove .030" from the remaining portion of the crown. This will make the actual depth of raised portion .200 instead of .170. With reference to the .300 and .440 raised crown pistons, .030" to be removed, in the same way this will now make the depth of raised portion respectively .330 and .470. In both cases, the piston should be strengthened by suitable alterations on the inside of the crown. We realize that the top land will automatically be reduced by .030" and this is in line with our recent tests. The idea of this modification is to increase the space between the piston and the cylinder head face. | ||