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).
Investigation into high oil consumption in 4¼-litre Bentley engines, finding cylinder heads were hollow.
| Identifier | ExFiles\Box 103\2\ scan0114 | |
| Date | 9th March 1931 | |
| GNH H.{Arthur M. Hanbury - Head Complaints} from Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} By.{R.W. Bailey - Chief Engineer} RHC.{R. H. Coverley - Production Engineer} Rm.{William Robotham - Chief Engineer} Kingsbury - 9.3.31. 4¼-litre Bentley Cylinder Heads. We have been investigating a high oil consumption job here, and in doing so we checked the cylinder head base for being flat. We found that it was hollow in the centre to an extent of .007". Another 4¼ head was checked and this one was found hollow to the extent of .006". Is this due to distortion after fitting, as one cannot imagine that the machining leaves it so much out. The following is a rough sketch of the heads:- Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} [Sketch of a cylinder head base with measurements] .002 Bolt holes. .007 .002 | ||