COLD WEATHER START

Evening Post, Volume CV, Issue 151, 30 June 1928, Page 18

COLD WEATHER START

■'■';:;■;■; ' ■ ;?:-jjs£ ;----',. -V Petrol will tiirtt.to vapour at atenK jperaturc of about 70deg. in the same way as water vaporises at 212deg. When steam strikes a surface colder than 212 dog. it will condense and again-become water. In thesame, way .-vaporised petrol will condense; i£ in contact with a cold manifold "after ltiaving the carburetter. The above is the reason why it is hard to start on a cold day. While the carburettor will davits work properly, the vapour, howe^;er,*^i the way to the cylinders, strifceßJJho xbld manifold, and so condenses^witft th%result that practically'nothing bu'fc,,air reaches.the cylinders. When the engine is cranked it really travels very slowly, and so the suction,, and the, movement of the mixture is; slow', thus increasing the chance for condensation. /Vt'^' , " What can we^do'to-start in cold weather? ;,If, when starting, we make the "mixture very rich, Ihen, even though most of the gas condenses on the way to the cylinders, the chances are that enough will reach .them to cause an explosion. Tho explosion will make the engine ■•■;revolve',^fast^ causing) a quick Auction and; a .cjujck moySment of the mixture,, thus;"'not* giving, the ' gas a chance to condense. Not only that, but because of the friction between the previously-condensed ■ gas and the fast-moving air,- the. condensed gasoline, which is on the.manifold,...will be made to'travel in the, direction of the cylinders and so get: into them, where, the temperature being high-from the former explosion, it will vaporise again. To enrich the mixture when starting, sometimes the carburetter is flooded by holding down, the float, but , perhaps more often much of the air is'choked off by means of a choke yalve. The valve is operated by a wire fastened to a rod or lever, either on the instrument board or steering column, when a solf-starter'is furnished, or by a wire wheh- passes through the radiator'and terminates in a small ring or hook, when the engine is cranked by hand. . | Remember that. the choke valve is a device for starting when the engine is cold. On a hot day, or when the engine is hot after a long run and but a few moments standing "idle, it would be better not to use the-.choke.: When used on a hot day and hot engine it may cause the engine to choke; that is, become filled wjjth so rich a mixture that it will not start. !'- *."'■.■ Another cold weather device found on most cars is the "season shutter." This should be closed in cold weather and open in warm. Few drivers pay any attention to it, but it will pay to see that it is open''when'the' weather is warna and closed when it is'cold.