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).
Graph comparing flow through a standard Bentley head EB 222 versus a 30° inlet valve seat head.
| Identifier | ExFiles\Box 31\2\ Scan121 | |
| Date | 29th August 1933 guessed | |
| CURVE 9 COMPARISON OF STD. BENTLEY HEAD EB 222 WITH 30° INLET VALVE SEAT HEAD FLOW THRU' PORT CU FT/MIN PRESS. DIFFERENCE ACROSS VALVE - "Hg (1) STD. HEAD. EB 222 (2) 30° SEAT HEAD 150 140 130 120 110 100 90 80 70 .6 .8 1.0 1.2 1.4 1.6 1.8 2.0 | ||