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).
Comparative table of performance data for various ignition coils.
| Identifier | ExFiles\Box 164\5\ img407 | |
| Date | 6th February 1939 guessed | |
| Type of coil. Max. Running temp.°C. Road performance. Time taken to start engine at 6°F.{Mr Friese} Standard Wraith. 124°C. Good performance. No misfires. 11 seconds. Standard Wraith. in metal case. 96°C. " " 10 " Delco. 178°C. Misfires at max. temperature. 5 " Delco new type. 111°C. Good performance. 13 " R.R. in metal-case 60 more turns on primary. No ballast. 136°C. " " 29 " INS.1 in metal case. RR large output without ballast. 142°C. " " 11 " INS.2 in metal case. RR similar to Lucas B.R. 122°C. " " 7 " Lucas Sports No ballast. 106°C. " " 10 " Lucas WT.1749 B.R. 117°C. No misfires on pick-up but misfire more readily under loading up conditions than Wraith. 12 " Lucas LT.1272 As fitted to Vauxhall. 91°C. 8 " Lucas in RR. Bakelite case. 105°C. Misfired on pick-up. No start. Standard Bentley. 105°C. Good performance. 10 secs. | ||