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).
Blueprint graph showing the Delco ignition curve and performance test results for two different cylinder heads.
| Identifier | ExFiles\Box 82\4\ scan0335 | |
| Date | 12th June 1936 guessed | |
| DELCO IGNITION CURVE UPON WHICH PERFORMANCE TESTS WERE TAKEN TIMED AT 5° B.T.D.C. STANDARD HEAD 10 - 20 MPH 3.53 SECS. 20 - 30 3.80 30 - 40 3.80 40 - 50 4.03 50 - 60 4.70 60 - 70 5.40 25.26 DE-TURBULATED HEAD 3.73 SECS. 3.66 3.73 4.08 5.00 5.45 25.65 BOTH CYL. HEADS 109 C.C'S AND 6.8:1 COMP. RATIO. Y-AXIS: ACTUAL FLYWHEEL IGN. ADVANCE X-AXIS: ENGINE R.P.M SIGNATURE: G M WYMAN | ||