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 foundry development and casting specifications for Cylinder Head part #637981.
| Identifier | ExFiles\Box 170\3\ img075 | |
| Date | 17th February 1936 | |
| COPY to: Mr. J.{Mr Johnson W.M.} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Wood from: L. V.{VIENNA} Cram - Flint February 17, 1936 I am returning to you a letter from Mr. Robotham to Mr. Olley dated January 30th. Our Cylinder Head, part #637981, represents a considerable number of years of Foundry development and as it now stands, weighs from 62 to 63 pounds finished. By referring to the notes, it will be found that we specify 3/16 walls everywhere except the combustion chamber and the bottom face. Over years of experience, we find that actual 3/16 walls represent the most economical Foundry practice. This includes scrap losses and pattern up-keep. It will be noted that we call for 1/8 fillets except as otherwise specified. This is general practice. On this part we have a considerable number of deviations because of the intricacy of the casting. The combustion chamber thickness and the bottom wall thickness have been established as a result of practical experience and are at the present time very satisfactory for our head bolt spacing. I believe that the latter is of primary importance in establishing these two dimensions, though the combustion chamber is undoubtedly seriously affected by compression ratio, detonation, etc. The bottom face and the combustion chambers are all in one big slab core which is made "bowed" to accommodate the natural warp of the casting. By this method the combustion chamber depths are held to reasonable uniformity. Castings are knocked out of the molds while they are still red and this practice, which has been in effect for several years, does not make us trouble. Our cylinder iron comes from the cupola at approximately 2850 deg. F.{Mr Friese} and actually poured into the mold at around 2750 deg. F.{Mr Friese} This high temperature of course makes necessary unusual care and preparation of molds and cores, but we are sure that the results warrant this special handling. L. V.{VIENNA} Cram | ||