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).
Performance and issues with larger inlet valves for the Phantom engine.
| Identifier | ExFiles\Box 17\6\ Scan131 | |
| Date | 25th August 1933 | |
| V7060. E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to Ey. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}2/MA.25.8.33. LARGER INLET VALVES. PHANTOM. These larger inlet valves give us about 6 BHP. increase at 3500 revs. We are right up against the valve bouncing speed with the standard Phantom valve, and therefore as soon as we fitted the big valves to LeC.3446 we ran into trouble. We are reluctant to fit stronger valve springs from the gear rattle point of view and therefore we lightened the valve in the head to LeC.3579 by drilling a hole in the stem to Ex.12011. From attached figures you will note that we are now only 2½ per cent heavier than the standard valve, even so we have fitted stronger valve springs than standard to be free from bouncing at 3500 R.P.M. If you have any other suggestions to make with regard to lightening this valve which might obviate drilling the stem we should like to have them. We have removed the re-grinding step which will have to be replaced. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||