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).
Bureau of Standards report on an endurance test conducted on Duffy 'Air-Line' spark plugs.
| Identifier | ExFiles\Box 33\3\ Scan071 | |
| Date | 17th August 1917 | |
| (COPY) THE BUREAU OF STANDARDS ------------- REPORT ON ENDURANCE TEST ON THE DUFFY "AIR-LINE" SPARK PLUGS. -- Manufactured by The Express Spark Plug Co. - Washington, D.C. Five Duffy "Air-Line" spark plugs were run six hours in the exhaust side of a Hall Scott, type "A-5", aviation motor driving a 9' propeller, 6.5' pitch at 1150 R.P.M. The plugs ran without misfiring the entire test, the electrodes showing no warpage or corrosion, and insulating material remaining free from carbon deposits and retaining its original glaze. No pre-ignition shown. The temperature of outlet cooling water was maintained at 155° F.{Mr Friese} Remarks:- The materials used in the construction make the plugs suitable for use under severe conditions. The insulating material will not fracture under sharp blows. Plugs are easily taken apart for cleaning and on re-assembly will remain gas-tight. Short length permits the use of ordinary pocket wrench on the shell nut, the brass shell threads also conform closely to cylinder threads. Where air resistance and weight are factors these plugs are particularly applicable. (Sgd.) WHETHERILL, Laboratory Assistant. August 17, 1917. | ||