INCREASING VALVE LIFE.

Press, Volume LXIX, Issue 20807, 17 March 1933, Page 8

INCREASING VALVE LIFE.

BENEFIT FKOM SALT COOLING. It is well known that the valves of an engine, especially the exhausts, are very highly stressed. In high-compres-sion sports engines the exhaust valve heads may become red hot, and thus act as a definite limiting factor to performance. Normally, tho only method of dissipating the heat is via the valve seatings, and this, at very high speeds, is not always enough. Therefore, the need arises for cooling the exhaust valves in some other manner. . A method adopted successfully in aircraft practice is to use salt-cooled valves. The stems are drilled up to the heads and a special metallic salt placed in tho hole. The lower end is then sealed. At high temperatures the salt vaporises and has the effect of withdrawing the heat from the head. Valves of this kind have been in use for some years, and there is now n possibility that they may be adopted by light car manufacturers, not so much for preventing incandescence as to increase the life of the valves, for, by maintaining them at a comparatively low temperature, sealing or pitting is avoided. It is interesting to note that large gas engines and certain forms of Diesel engine aro provided with water-cooled valves.

Distributor point cleaning is a task that many owners like to reserve to themselves. In doing so, some of them make a mistake that often makes necessary the early purchase of a new set of points. Instead of being content to remove tho raised places on the platinum or tungsten, they try to eliminate the pits. This is unnecessary and wasteful of the point material. The depressions make no difference in the efficiency of the units. The raised spots do.