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).
Investigation into exhaust valve stretching, concluding it is caused by insufficient tappet clearance.
| Identifier | ExFiles\Box 14\6\ Scan035 | |
| Date | 1st November 1928 | |
| X7230 To CWB. from Hs.{Lord Ernest Hives - Chair} c. to Mx.{John H Maddocks - Chief Proving Officer} c. to EP.{G. Eric Platford - Chief Quality Engineer} Hs{Lord Ernest Hives - Chair}2/LGL.11.28. STRETCHING OF EXHAUST VALVES. X7060 With reference to CWB15/GM29.10.28. The stretching of the exhaust valves in France is proved to be due to insufficient clearance in the tappets. 12-EX car which developed this fault in France after 400 to 500 miles, completed a further 15,000 miles without any further trouble after the tappets were set to the present standard clearance which is .006" adjusted when the engine is cold. The modified exhaust valve was rushed through xx but was never proved to be any advantage for this particular trouble and also had the serious disadvantage that it caused a bad clatter from the valves. No Phantom cars have ever been sent out with the heavier exhaust valve. Since that time we have kept a careful record on experimental cars and we are satisfied that when the valves are adjusted correctly there is no trouble due to stretching. Hs.{Lord Ernest Hives - Chair} | ||