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).
Graph showing Delco valve spring ratings under low pressure.
| Identifier | ExFiles\Box 28\1\ Scan224 | |
| Date | 4th February 1931 | |
| DELCO VALVE SPRING RATINGS. LOW PRESSURE. 4-2-31. DEFLECTION - INS. OUTER SPRING .150 .100 .050 INNER SPRING 300 200 100 'C' INNER 14.8 LB/IN. 'C' OUTER 238 LB/IN. 'G' INNER 14.8 LB/IN. 'G' OUTER 417 LB/IN. LOAD - LB. INNER SPRING 1 2 3 4 5 6 OUTER SPRING 10 20 30 40 50 60 | ||