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).
History and properties of chilled cylinder bores in Bentley engines and advocating for better record-keeping.
| Identifier | ExFiles\Box 103\2\ scan0031 | |
| Date | 11th March 1939 | |
| -2- Present Production. There is every reason to believe that the present 'M' series Bentleys will not be too good for bore wear. There is not sufficient evidence available to prove the fact, and bearing in mind the amount of trouble that is caused by major modifications towards the end of a series, we have little justification in making a change. It is worth while looking into the past history of the job, however, even if only to show how easy it is to walk into trouble of this kind when inefficient records are kept. Up till June 1937, all production Bentley cylinder bores were chilled after casting, and at that time the practice ceased. In order to determine whether there was any value in it we give below the following chassis, which are the last that we can trace with chilled bores. Chassis No. Engine No. Series. B.38.KT N.4.BY. 1st. 100 in 'K'. B.182.KT W.7.BP. " " " " B.194.KT C.4.BJ. " " " " B.1.KU U.4.BR. 2nd. " " " From this it is suggested that the chilled bores went off early in the second half of 'K' series. In January 1937 the Phosphorous content was reduced from .4% to .25%. The following Brinell figures are given for reference. Brinell. Chilled Bores 250 - 270 Non chilled ) (.25% phosphorous) ) 201 - 229 When alterations such as these are carried out the closest records should be kept, so that the true specif-ication of our product may be known to an engine, not half a series. | ||