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).
Results of tests on Peregrine engine camshafts with various toe profiles.
| Identifier | ExFiles\Box 1\10\ B001_X106 TO X 110-page050 | |
| Date | 20th September 1932 | |
| Y 107. To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/KT.20.9.32. PEREGRINE CAMSHAFTS. We have now completed a series of tests on the camshafts with the reduced toes, produced in the temporary method BY/CS.5/E22.7.32. The temporary job succeeded in cutting down the length of the toe, but in doing so the accelerations over this range were raised and in consequence the valve gear was noisy. Curve Rm.{William Robotham - Chief Engineer}Pr.23 shews the improvement in low speed M.E.P. due to reducing the toe which confirms the results obtained by using increased tappet clearance. The curves are not directly comparable because 2 S.U. carbs. were used with the short toe camshaft. Curve Rm.{William Robotham - Chief Engineer}Pr.24, however, shews that there is not much difference in low speed M.E.P. between two and one S.U. carburetter. Curve Rm.{William Robotham - Chief Engineer}Pr.25 indicates that when the duration of valve opening is reduced, and the toe eliminated, the advantage of the smaller inlet valves is considerably reduced. At present we think we get smoother running with the small inlet valves, but the size can finally be determined when we get the ultimate camshaft and carburetter. Curve Rm.{William Robotham - Chief Engineer}Pr.26 was taken to see if, with the reduced toe, our previous experience that two exhaust INLET cam forms gave better results than one inlet and one exhaust, still held good. It will be observed that the two inlet cam forms give superior results. Our tests of slow speed full torque on the road have been confused by ignition troubles, but we think at present that the longest duration camshaft that we shall be able to tolerate is the one shown on Rm.{William Robotham - Chief Engineer}Pr.24 - Diagram text: B 3 8 Ex In 38 34 O13 TAPPET CLNCE. SHORT TOE | ||