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).
Specifications and history of exhaust and inlet valves for the Bentley 4-litre 6-cylinder engine.
| Identifier | ExFiles\Box 131\2\ scan0220 | |
| Date | 6th July 1938 | |
| Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} 6.7.38. Bentley 4-litre 6-cyl. engine. I have made enquiries re the above. There has not been any known trouble with the exhaust valves. The history as far as I have been able to ascertain is as follows:- Exhaust Valve BM.7856 (Hadfields "Hecla" Steel) 38 m/m dia. throat 3 m/m width seating @ 30° 43.2 m/m head. The bearing diameter of this valve was lengthened by 17 m/m to eliminate rock when valve opens. All production cars were either fitted or modified with this valve. Inlet Valve BM.8831. (5% C.H.N.S.) 40 m/m dia. throat 2.9 m/m width seating @ 30°. When this valve was passing engine experimental stage, the head was 50 m/m dia. for a 45 m/m dia. throat, and experiment with flow meters and gas speed indicators caused the valve to be modified to 45 m/m dia. head for a 40 m/m throat. Weight of each valve is 4 ozs. 8 drms. Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} Please return drawings when finished with. | ||