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 valve timing, including a diagram and notes on overlap and tappet clearance.
| Identifier | ExFiles\Box 178\3\ img090 | |
| Date | 29th February 1932 guessed | |
| (2) In the past RR. cars have been exceptionally good for their HP., and we must not expect to be free from criticism - some of it right, but much all wrong. VALVE TIMING. We must be alive to the fact that excessive overlap may spoil slow running. If this is not so valve timing is settling down to 5° - changeover -i.e. E.C. & I.O. [Diagram with labels:] 5° I.C. 50° E.O. 40° .020 tappet clearance. 2 equal cams, exhaust lengths of 225° with this clearance (probably our 240° with .013 clearance) 112° apart. The only doubt is how much overlap. R.{Sir Henry Royce} | ||