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Show LEAN' MIXTURE IS CAUSE OF FIRES Carburetor Gets Out of Adjustment Ad-justment and Then Mischief Mis-chief Is Done. "How tliJ your cm- lake lire?" "I don't know, i heard It pop buck at the ciirhuretni, siul suddenly discovered discov-ered that It was on rtu" "What made It hacklire iu the carburetor?" "I don't know. We can't tttul out because be-cause the car is a total loss." This is no Imaginary conversation because cars liave burned In the past and will again In the future due to backfiring in the carburetor. Cause Is Lean Mixture. The most frequent' cause is a lean mixture. This means more air in the mixture than usual. The enrburetor gets out of adjustment In some way and the mischief Is done. A lean mixture Is slow-burning.. It burns all during the power stroke, all during the exhaust stroke, and it is still burning when the Inlet valve opens, admitting the fresh mixture. This takes fire and the flame runs back to the carburetor. If there is any gasoline dripping from the carburetor a heavy vapor is formed, extending under the engine, where It is held by the mud pan. The flame spreads under un-der the engine and soon reaches the tank, melting the connections and releasing a flood of gasoline. Lean mixture may be clue to derangement de-rangement of the carburetor or a leaky inlet manifold. Spray nozzle " too far closed, auxiliary air valve spring too weak or valve stuck open or clogged fuel line are a few carburetor car-buretor causes. A leaky inlet manifold mani-fold may be detected by running the engine and Injecting oil around the joints. Oil will be sucked in at the leak where the bolts must be tightened tight-ened or a new gasket Installed In place of the leaky one. Inlet Valve Defects. We now come to troubles of the Inlet valve, which indeed are very rare. The valve lifter may be out of adjustment, leaving no clearance, or actually pushing the valve off Its seat. If there is little or no clearance the valve will hold compression when the engine is cold, but will leak when the engine warms up, due to lengthening of valve stem, and, of course, popping pop-ping in the carburetor occurs immediately. immedi-ately. Set the clearance at about two thicknesses of newspaper. Occasionally Occasion-ally this valve may become stuck, so that it cannot close. This may be seen from the outside, as there will be an unusually large space between the valve stem and lifter. Electrical troubles now engage our attention. With a single coil and distributer system such as used on (he majority of cars there would be Home distributer trouble or a short circuit of the distributer wires. See that all wires are properly insulated and wipe all jlust from distributer head. If you know how to open the distributer you should wipe out 'the Inside occasionally, using a cloth dipped in gasoline. This will remove all accumulations of dust, which will cause short circuit if allowed to remain. |