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).
Valve bounce and surge issues for B.60 & B.80 engines.
| Identifier | ExFiles\Box 124\2\ scan0324 | |
| Date | 16th July 1941 | |
| 1094 To Rm.{William Robotham - Chief Engineer} from Jnr.{Charles L. Jenner} c.c. to Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} Jnr.{Charles L. Jenner}10/JH.16.7.41. VALVE BOUNCE & SURGE B.60 & B.80. Ref. Rm.{William Robotham - Chief Engineer}1/HH.11.7.41. To fit the Buick double valve springs to the inlet valves would result in the engine not running up to the speed we want, the reason is that the poundage is too low by 10 lbs in the closed position and Buicks valve lift is .35 against our .4. There is a mechanical objection also the whole rocker shaft would have to be raised and anew rocker cover made. There has been two failures to design a satisfactory single spring with closed ends and we are far from confident that PL.673 (yet unmanufactured) will not break due to the large stress range under which it works. So long as we have a large valve lift and the present accelerations we think we are committed to double springs and there is no reason why they should not be designed with closed ends to overcome surge. The present ones are Ph.III springs having equally spaced coils. To increase the bounce speed of the valve gear for the 3 1/4" bore engines we can rise from 4150 to 4400 by using a drilled up inlet valve and a steel tubular push rod, the tubular rod is half the weight of the solid one for the same collapse load. All Aluminium engine. The silence of the valve gear should be acceptable with dural push rods and no hydraulic adjustment, this was Swindall's experience on P.III, barrel tappets were used and no tappet spring. The cost of the duralumin push rod is worth some thought when consideration is given to the saving of the hydraulic pieces. This set up should result in the Engine going up to 4400 before bounce occurs. Cont'd.{John DeLooze - Company Secretary} | ||