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).
Persistent issues with automatic tappet adjustments, specifically a plunger fault and valves being held open at high speeds.
| Identifier | ExFiles\Box 17\6\ Scan179 | |
| Date | 5th February 1934 | |
| To Rm.{William Robotham - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Std. X7060 Hs{Lord Ernest Hives - Chair}/Std.19/KW.5.2.34. Automatic Tappets Adjustment. ------------------------- With reference to the troubles being experienced with the Vulture Silent Tappet Mechanism - we have cured the trouble of valves being held open at high speeds by fitting very high rating springs. We still have a certain unreliable element about them however. Occasionally a plunger will "breathe" - i.e., sink slowly and suddenly rise to its correct position, function perfectly for a time and then repeat this fault. This trouble is particularly apparent on the new cylinder head for 28-EX car, with which we are also getting trouble at high speeds. At 3000 r.p.m. No. 1 inlet valve only is held open; at 3250 r.p.m. No. 1 (inlet) and No. 10 (exhaust) valves are held open. I should like to know whether Cadillacs have had any similar troubles. I should also like to know whether Cadillacs have ever used a ball plunger valve, and if so why they still stick to the poppet valve in preference to this type, as we are inclined to suspect the ball valve of being the source of some trouble. Hs{Lord Ernest Hives - Chair}/C.S.Steadman. | ||