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).
Tests comparing different types of bottom tappets for the Phantom III engine.
| Identifier | ExFiles\Box 96\2\ scan0177 | |
| Date | 9th December 1936 | |
| 359 To Hs.{Lord Ernest Hives - Chair} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}9/AP.9.12.36. PHANTOM III BOTTOM TAPPETS. Further to our report Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}14/JH.1.9.36., tests have been carried out with regard to bottom tappet wear, when the auto-adjusting valve gear is put out of action and the valve clearances set in a normal manner. In the report we stated that after running a car set as above, the Fescolised (standard) bottom tappet together with the camshaft were in a very bad condition, and that it was suspected that at some period since fitting, the valve gear had been choc-a-bloc. We can now confirm this view, as we have since repeated this test on a bed unit with excellent results so far as the Fescolised tappets are concerned. Along with the Fescol tappets and under the same conditions were fitted S/ZN. tappets with the normal cloudburst hardened face. On one bank of the unit the bottom tappet springs were left out and along the unit, exhaust valve clearances were set at .006, .008, .010 and .012 with the inlets all at .006. Upon dismantling after 8 hours full throttle running up to speeds of 4500 R.P.M., the following results were obtained. (1) Fescol tappets irrespective of clearance were in very good condition. (2) Deletion of bottom tappet springs made no appreciable difference to the conditions. (3) Cloudburst hardened tappets even on inlet valves or the exhaust with large clearances are not good enough and get badly scored with grooves on the surface. With exhaust clearance under .008 there are deep grooves. We should mention that KE.965 exhaust valves were used. A further test has been carried out comparing "Hykro" with Fescol with and without auto tappets. Some of the "Hykro" tappets were normaly carburized and the others carburized and cloudburst, the latter being in slightly the better condition. continued. | ||