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 discussing the extra oil system for the starter carburetter and cylinder bores on various engine models.
| Identifier | ExFiles\Box 74\2\ scan0092 | |
| Date | 26th October 1925 | |
| 4687 Expl: Dept: Hs{Lord Ernest Hives - Chair}2/LG. 26th. Oct. 1925 Dear OY., Re. Extra Oil Coupled to Pilot Jet. Thank you for your OY1-E-101625. We have never been very taken up with the scheme of connecting the extra oil to the starter carburetter. We have worked on the idea that we want the starter carburetter working for the minimum amount of time. We all know that any form of starter carburetter or choke is the very worst offender for drenching the cyls. with petrol. We consider that the outstanding advantage of using exhaust heat, is that it enables the engine to be run with the starter carburetter for a minimum time. We should doubt that much oil would get through the extra oil scheme owing to viscosity effects. There is a definite restriction in the pipe at the extra oil valve. As regards the suggestion of feeding the oil direct into the cyl. bores. We think with this you would find that you got excess. We have proved that with the present 40/50 HP. scheme of extra oil, very little oil gets through because the piston acts as a cut-off valve to the supply. Most of the oil gets through when the piston is above the extra oil conn. On the New PhantomCodename for PHANTOM I we do not need any extra oil. The big problem we have at the present time is excess of oil. We think it is most probable that we shall have to cut off the main supply of oil to the intermediate bearings and only supply the three main bearings as we do on the 40/50 and 20 HP. We will write you further on the other points raised in your memo. for which we are very grateful. Hs{Lord Ernest Hives - Chair} | ||