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).
Test report and recommendation for Mercury CB3 Sparking Plugs following a series of five performance tests.
| Identifier | ExFiles\Box 172\3\ img037 | |
| Date | 1st October 1937 | |
| X.4295.- MERCURY SPARKING PLUGS. Mercury CB3 Sparking Plugs were subjeted, along with various other makes, to the following tests:- Test 1. Engine run on weak mixture for a long period and then run with full compression to see if misfiring occurred or insulation failed. Test 2. Engine run with over-strong mixture - the engine was run on theroad for 15 minutes with primer cock open to see if plugs would soot up. Test 3. Engine run with excess of oil to cylinders - when plugs were removed they were all wet with oil. Test 4. Test bench tests for pre-ignition. Test 5. Test to see amount of gas leakage past packing of insulators. they passed through the whole of the above tests O.K. The Mercury plug is made in Birmingham. it is of simple construction using French porcelain as an insulation. The plug is completely detachable and it is an easy matter to fit a new insulator. The price is approximately 1/6 each compared with 2/1 for the Lodge. We recommend that we order 500 of these plugs for a start so that we can be certain that the quality will be maintained. HS.{Lord Ernest Hives - Chair} RR. 5000-1-10-37 RR. GRP. 11/C/344. | ||