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).
Table of measurements comparing the nominal and measured choc-a-bloc length of various valve springs.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan021 | |
| Date | 31th March 1928 | |
| CHOC-A-BLOC LENGTH OF VALVE-SPRINGS. | PIECE NO. | MEASURED C-A-BLOC LENGTH | NOMINAL C-A-BLOC LENGTH | RATIO: MEASURED / NOMINAL | NOMINAL + 2/3 COIL | |---|---|---|---|---| | E.9905 | 1.240 | 1.160 | 1.070 | 1.240 | | " | 1.242 | 1.160 | 1.070 | " | | E.50738 | 1.000 | .986 | 1.015 | 1.005 | | " | 1.015 | .986 | 1.030 | " | | E.70442 | 1.397 | 1.360 | 1.029 | 1.386 | | " | 1.390 | 1.360 | 1.022 | " | | E.30889 | 1.095 | 1.024 | 1.070 | 1.109 | | " | 1.110 | 1.024 | 1.083 | " | | E.30888 | 1.140 | 1.029 | 1.108 | 1.048 | | " | 1.125 | 1.029 | 1.092 | " | | E.29832 | .925 | .895 | 1.032 | .920 | | " | .900 | .895 | 1.005 | " | | E.29833 | .898 | .828 | 1.085 | .845 | | " | .830 | .828 | 1.001 | " | | E.14820* | 1.050 | 1.072 | 1.037 | .983 | *ENAMELLED. TSH. 31/3/28 | ||