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).
Design changes and specifications for an experimental Bentley aluminium cylinder head.
| Identifier | ExFiles\Box 86\1\ scan0028 | |
| Date | 28th September 1933 | |
| K219. To BY.{R.W. Bailey - Chief Engineer} from E/JNR.{Charles L. Jenner} E/JNR.{Charles L. Jenner}1/HP.28.9.33. c. Wor{Arthur Wormald - General Works Manager}-Hs.{Lord Ernest Hives - Chair} RHC.{R. H. Coverley - Production Engineer} re Bentley Aluminium Cylinder Head. We send you herewith drawing: LeC.3645 shewing an experimental aluminium cylinder head with a compression ratio of 7.5 to 1. In view of our recent troubles with leaded petrol we have increased the surface of the exhaust valve seat and altered the angle to 30°. This makes the exhaust valve 6% heavier. The drawing calls for the sparking plug insert to be made in aluminium bronze and the valve seats in N/C.M.Steel. The cylinder head has been made to fit the existing cylinder block except for the size of the tappet rod holes which have been increased to .525" diameter to accommodate the new dural push rod. Using a gasket of .010" thickness it is necessary to reduce the height of the piston .04 to keep the top of the piston sufficiently clear of the cylinder head. It will be noticed that the rocker shaft is now in two lengths to permit of the increased expansion of the aluminium head. This affects the fixing of the rocker cover making the spacing of the thumb nuts unequal. We send you also herewith LeC.3653 shewing the duralumin tappet push rod. E/JNR.{Charles L. Jenner} | ||