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).
Instructional leaflet for the Molla Sparking plug No. 6, detailing its disassembly and regulation.
| Identifier | ExFiles\Box 33\3\ Scan120 | |
| Date | 9th March 1921 guessed | |
| 111/113 Gt Portland St GARAGE "SERVICE" EQUIPMENT LTD., 9, Princes Street, Hanover Sq., London.W.1. The MOLLA SPARKING plug. No 6 PATENTED IN ALL COUNTRIES THE ONLY SPARKING PLUG IN THE WORLD WHICH IS CAPABLE OF BEING Taken ENTIRELY to pieces, and REGULATED Fig. 1 Unscrew the wire connection and top nut. Fig. 3 Take off the porcelain cup and push out electrode. If it is stuck in the base put back the top nut for a couple of threads on the end of the stem of the electrode and give the end of the stem of the electrode a sharp tap with some tool. It is important to put on the nut before tapping the stem in order to avoid spoiling the thread of the stem. Fig. 4 The plug being now in pieces clean all parts with petrol. To reassemble the parts grease the cone of the insulator, where it fits in the base and adjust it with a slight rotary movement, holding the base in the left hand, and gently pulling the stem of thee electrode till the electrode is in position. Fig. 5 After this replace the porcelain cup, the brass washer, the spring washer, the top nut and regulate the spark gap with the electrode to the desired space. It is useless to attempt to adjust this spark gap by turning the "T" shaped points. The electrode is lifted, turned by the stem and when the gap is sufficient, pulled home and fixed by tightening the washers and nuts. | ||