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).
Experiments with various bottom washers, grommets, and valve stems to improve performance and reduce costs.
| Identifier | ExFiles\Box 144\3\ scan0115 | |
| Date | 2nd September 1936 | |
| -2- Hs{Lord Ernest Hives - Chair}/FD.{Frank Dodd - Bodies}17/KW.2.9.36. Various shapes of bottom washers have been tried, the best results have been obtained using a Bentley valve guide, grummets and bottom washer so arranged that the grummet had the full spring pressure of the outer and inner coils. One of the faults we had to find with the present Ph.III type is the lack of spring pressure on the grummet as compared with the Bentley. Our tests have shown that spring pressures being equal the Bentley grummet is better than Ph.III. We have tried chromium plated valve stems with close fitting guides, .001" clearance. These showed 60% improvement for overoiling, the percentage is arrived at by the time taken for oil to pass the valve lip running without grummets on the rig. As the results on 33-EX running without the oil supply to the valve stems is so favourable, we are proposing to carry out the same modification to 33-EX, 10,000 miles car, and also 37-MX{John H Maddocks - Chief Proving Officer} in the exptl. garage. This should give us some results fairly quickly. Should we be able to standardise this scheme, we could throw away bottom washers and grummets, and increase the valve guide in height, making the top convex as in aero practice. This, together with close clearance valves, should give excellent results and save cash. A further report on the progress of these experiments will follow after sufficient mileage has been covered. Hs{Lord Ernest Hives - Chair}/F.Dodd. | ||