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).
Leading experimental features, specifically adjustable tappets and four-port cylinder heads.
| Identifier | ExFiles\Box 91\2\ scan0349 | |
| Date | 18th September 1937 | |
| 2. Report on leading experimental features. Adjustable tappets ( deleting hydraulic mechanism ) on Four-port Cylinder heads, incorporating :- LOP. R.{Sir Henry Royce} 88786. Four port cylinder heads. Lec. 5441 Solid rocker gear. Lec. 5444 Modified oil feed to rockers. 12 - R.{Sir Henry Royce} 88782 Solid inlet valves . W/SLY. 12 - W. 88447 Strengthened exhaust valves K.E.965. 12 - RR. 175 Valve springs 'A' side. Standard Bentley made at R.R. 1p S/CV. 12 - RR. 260 Valve springs 'B' side. Standardised as alternative spring for Bentley made by Tempered Spring Co. in Swedish wire. Lec. 5401 Valve lift curve - long toes - 210° duration. Objects of scheme. (a) To avoid the complications and troubles experienced with hydraulic tappets and also to reduce cost and weight. (b) To reduce top-overoiling and thereby improve oil consumption. (c) To obtain long periods between adjustments by increasing the reliability of the valves, by producing a camshaft with a wide lattitude and by improving the lubrication of the rocker gear. ------------- The arrangement was satisfactory in all respects. At no time did the tappets cause any irregularity in the starting, or running of the engine. The average oil consumption for the mileage was 1,950 m.p.g., twice as good as any previous Phantom III on 15,000 miles test. | ||