GAS ENGINES 523 



carburetor should be varied and the results carefully noted. 

 Too lean a mixture may cause missing or backfiring, and too 

 rich a mixture weak explosions, missing, or explosions in the 

 exhaust. After the strength of the spark has been found 

 satisfactory, the timing may be examined. Too early a 

 spark weakens the stroke by knocking or kicking backward, 

 and a spark timed too late comes when the piston has 

 already started to travel downward and the full force of the 

 explosion is not utilized. The heat of the engine also should 

 be watched. Overheating due to overworking the engine, 

 late spark, rich mixture or failure in the cooling system 

 may generate a red heat in some part of the cylinder, and 

 this may fire the incoming gases before the proper time. 

 Sticking or riding valves lower the power of an engine by 

 weakening the compression in the combustion chamber, and 

 imperfectly timed valve action has the same effect. In the 

 cylinder parts wearing or grooving of cylinder walls or 

 wearing or breaking of piston rings may allow some escape 

 of gases and so decrease the power. 



Specific instructions for the care of any particular type 

 of gasoline engine will be found in the manufacturer's 

 instruction book which accompanies a new engine or may 

 be obtained upon application. Careful study of directions 

 for operation and lubrication may prevent annoying delays 

 and expensive repairs. 



BIBLIOGRAPHY 



Brown, A. B. Handbook of Carburetion. John Wiley & Sons. 



Dyke, A. L. Dyke's Automobile and Gasoline Engine Encyclopedia. 

 U. P. Book Co. 



"Gas Engine Facts," Gas Review, 1911. A. M. Thresherman, Madison, 

 Wis. 



"Gasology," ibid., 1910. 



Hirschfeld and Ulbricht. Gas Engines for the Farm. John Wiley 

 & Sons. 



Hobbs, Elliott, and Consoli ver. The Gasoline A utomobile. McGraw- 

 Hill. 



Norris, Earle B., Winning, and Weaver. Gas Engine Ignition. 

 McGraw-Hill. 



