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).
Valve gear noise issues, detailing the evolution of valve springs for the Phantom model.
| Identifier | ExFiles\Box 66a\2\ scan0097 | |
| Date | 13th May 1929 | |
| To OY. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} +8060 Hs{Lord Ernest Hives - Chair}/RmL/LG13. 5. 29. +290 With reference to your letter of the 2nd. inst. re. Valve Gear. Without going into the mathematics of the valve spring, perhaps it would be useful if I ran over all the practical information we can give you on the subject. In the first place we think we have obtained a fairly good and silent valve spring by means of trial and error. The original single spring on the cast iron headed Phantom had the main disadvantage that it became very noisy above 40 m.p.h. on 3rd. speed. With the introduction of the turbulent head a double valve springs was produced which we found had several periods quite low down which set up a marked clatter. We then produced valve spring E.78071 which is quite the best spring we have so far had and is silent up to over 50 m.p.h. on 3rd. on the Phantom. Using E.78071 we think we have little or no trouble with noise from the spring. The noises connected with the valve gear which still haunt us are :- (1) Warming up period. Due to the aluminium head expanding much more rapidly than the push rods, there is a noisy period when the car is warming up due to the clearance between the rocker and push rod increasing to about .015" - maximum. (2) Unless the valve stem is a very good fit contd :- | ||