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).
The design of cylinder block EB.2561 regarding valve tappet covers and oil deflecting ribs for the 4 1/4 litre Bentley and 25/30 models.
| Identifier | ExFiles\Box 86\1\ scan0216 | |
| Date | 9th November 1936 | |
| Reiles 219 SNPL BY: c. Rm.{William Robotham - Chief Engineer} RHC.{R. H. Coverley - Production Engineer} Da.{Bernard Day - Chassis Design} H/JNR.{Charles L. Jenner} E.1/HP.9.11.36. Cylinder Block EB.2561. With reference to the large bore cylinder block used on both the 4 1/4 litre Bentley and the 25/30, we notice that the old oil deflecting ribs used with the original style of valve tappet cover held on with hand screws have been incorporated in the casting, in spite of the fact that the tappet covers are now studded on. Also the stud bosses for these tappet covers have all been made blind, with the exception of a few at the bottom on which there is no room for blind bosses. The object of studding on the valve tappet covers was partly to avoid the complaints of oil leaks which occurred with the hand fixing, and in view of the studding we think that the drainage ribs are no longer necessary. The blind bosses are also not necessary, as the stud holes do not pass into the water jacket. E.{Mr Elliott - Chief Engineer} | ||