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).
Letter from Chrysler Corporation to Mr. W. A. Robotham concerning valve temperature and tappet adjusters.
| Identifier | ExFiles\Box 158\4\ scan0285 | |
| Date | 19th December 1938 | |
| CHRYSLER CORPORATION Detroit, Michigan, U.S.A - 2 - Mr. W. A.{Mr Adams} Robotham December 19, 1938 affect on valve temperature. As a matter of fact, an expanding section from the valve to the manifold will materially reduce temperatures because of gas expansion. Mr. Vincent Young, Chief Engineer of Wilcox-Rich, advises me that although there is no direct reason why a hydraulic tappet adjuster should produce lower temperatures, that indirectly, because when using a hydraulic adjuster no guiding ramp is required on the exhaust cam, the heating conditions on the exhaust valve are less; that is, that when a guiding ramp is used it opens the valve earlier and earlier as the engine heats up and so produces the effect of a slightly opened valve during periods of high pressure and temperature in the cylinder, which tends to heat the valve by leakage. This opening effect may, in extreme cases, amount to 45° crank shaft travel and so start to open the exhaust valve 90° from bottom center with a marked heating effect on the seat of the valve and a tendency to burn both valve and seat. I hope the above will be of some interest and use to you. May I extend to you best wishes for a Merry Christmas and a happy and prosperous New Year. Sincerely yours, A.{Mr Adams} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Herreshoff A.{Mr Adams} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Herreshoff Chief Engineer of Research AGH/EF | ||