VALVE KNOCK

NZ Truth, Issue 1190, 20 September 1928, Page 15

VALVE KNOCK

Noises In The Head : .... „ . . . i . Overhead valve engines are admittedly noisier ; m operation than engines: yvhich, have their, valves at the side, but. the adoption of ' the covered- in -head has; reduced i the ciatter from the push -rods and : roftkers. considerably. ' ; TN order -to secure the maximum, of . silence from,, an- overhead ; valve engine, the clearance .has to be .very small, addition; . lias to be checkedi^^ffy if ew vh'tinelred; miles to ■ erisupe Us jr idirig. b f h ; :thi^a;c'count /many': owners make their -clearances 'a good deal greater thanvthe limit iof safety; and.yin conssquejnce, ''their, engines, malse; s no, small aixib'u'nt of '.^noiise m operation.:- • \ > Strang§}y ■ enough,^ how&verv; \\ Is not the val'yes, as a whole* ; that;. mak e the objectloriable noise, but nearly always one or two' only. ■ '. ' "~. . . .■ With a. little care the offenders can be traced, and .by,. a. reduction, of .the clearance the. who^e^f . the ' yalves.-ban be made ' even; -and -quietness. 1 of "running gained.' • ],' , ■■.; v . "*-'"4^ : \? : .-.' ■ The method; to ; be .used .Ih.vd.e*' teoting> the^ nqisji • yalyies: Is ejujte . s|mp|i9.;'-''- / :v/:,v •:';,.- :y'. ••;-_.,:' ;;.-. ; : The engine^ must" 'be .kept -running;. at a moderate 'speed with" the- valved expcised.- The ; blade' of a -pocket- knife is then pushed between the tappet and the rocker until all the play ,1s taken up.- ■■';••: '• ■•• ; -- ; -- .-.-.-•v.' ' ""',- . \--- ..- It willbe found that the ". objectionable clatter will disappear " : "wKen""~ the knife" is : pushed '• under the : offending rockers. . -■ l; ■The engine should r ,then be stopped and the clearance of " the valves '■' perfected! !•■-"• ;/ •'■■' ; ; -''■ ■■ • ■■ ; '