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).
Engine pre-ignition from over-heated plugs and a knocking sound in car 7 CA.
| Identifier | ExFiles\Box 181\M11\ img192 | |
| Date | 8th August 1919 | |
| 7CA OPINIONS RE KNOCKS ORIGINAL To EH. from R.{Sir Henry Royce} Copy to CU. " " BN.{W.O. Bentley / Mr Barrington} " " ERC. " " DA.{Bernard Day - Chassis Design} X 682. RE CAR 7 CA. X 3413 I am very pleased with your explanation of the poor running of 7 CA, but I have never before remembered having preignitions on our car engine through over-heated plugs, and thought the Lodge plugs were quite safe from this trouble, except in aero engines where the duty of mean pressure is enormously greater. Regarding the knock in 7 CA. Mr. Elliott had the impression that it was in the coupling under the floorboards. I had the impression that it was a piston or little end. You will be able to settle this probably by examination of the pistons parts. R.{Sir Henry Royce} | ||