THE acute operational problem of spark-plug fouling in both the aviation and automobile industries is discussed in this paper, with special reference to the use of a tricresyl phosphate scavenger mix, which has been found to permit the laboratory aviation engine to run for 62 hr without fouling.
The mechanism by which tcp relieves spark-plug fouling is believed to be the prevention of formation of metallic lead, but additional factors include the formation of lead salts having low electrical conductivity; the reduction in deposition of free carbon, and the production of soft, powdery deposits, which slough off easily, compared with the usual hard, glazed form.
The successful use of tcp, as indicated in both laboratory and field tests, points to a future in which spark-plug fouling may become one of the minor causes of ignition failure.