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).
Calculations and test results for inlet valve bounce.
| Identifier | ExFiles\Box 124\2\ scan0327 | |
| Date | 16th July 1941 | |
| To Rm.{William Robotham - Chief Engineer} c to Jnr.{Charles L. Jenner} Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}12/JH.16.7.41. 1044 B.60 Inlet valve bounce. METHOD. The following calculations are made on the assumption that valves bounce when the inertia of the decelerating valve parts is greater than the spring load. The load on the spring due to this inertia is equal to WA{Mr Wallis}/g where W is the weight of the valve parts (at the spring CL) A is the deceleration of the valve. Any change in A is proportional to the square of a change in engine r.p.m. Valve bounce will always occur at the same value of WA{Mr Wallis}/g Therefore if W increased A must decrease, and the valve bounce speed will come down proportionately to the square root of the weight increase ratio. RESULTS. Valve bounce speed with standard set up R.P.M. 4150 Standard. Bounce speed with standard tappet, drilled valve and dural or tubular steel rod. 4420 Best with standard tappet Bounce speed with Halford tappet, drilled valve and dural rod. 4250 Best with Halford tappet Bounce speed with Halford tappet, drilled valve and solid steel rod. 4040 Bounce speed with Halford tappet, standard valve and solid steel rod. 4000 Conclusions. The outstanding feature of these figures is the effect of the lightened push rod. A drilled up valve is worthy only 40 r.p.m. with a Halford tappet and 50 r.p.m. with a standard set up. Cont'd.{John DeLooze - Company Secretary} | ||