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).
Data table comparing delivery results through a needle valve under various conditions.
| Identifier | ExFiles\Box 65a\3\ scan0164 | |
| Date | 7th November 1929 guessed | |
| Standard Conditions | With largest banjo reasonable cross holes drilled out to suit. | With straight through type nut & nipple. Delivery through needle valve. | 75.0 | 76.7 | 81.4 Delivery through needle valve seat, needle removed. | 78.0 | 79.1 | 83.8 | ||