or subjected to a load. Before the cylinders are replaced on the engine base, heavy brown paper gaskets should be made to place between the cylinder base flange and top portion of the engine crank case. The best method of making these gaskets is to tamp them. out by placing the sheet of brown paper over the mouth of the cylinder and directing a series of light blows with a machinists ball peen hammer against the sharp edges of the casting. This will cut the paper exactly to the form of the base flange and cylinder bore The holes in the flange may be indicated in the same manner or may be punched through with a steel drift. The same process may be used in making irregular shape gaskets of other materials such as asbestos or rubber packing. Before placing the cylinder over the piston it is imperative that the slots in the piston rings are spaced equidistant and that the piston is copiously oiled before the cylinder is slipped over it. When reassembling the inlet and exhaust manifolds it is well to use only perfect packings or gaskets and to avoid the use of those that seem to have hardened up or flattened out too much in service. If it is necessary to use new gaskets it is imperative to employ these at all joints on a manifold because if old and new gaskets are used together the new ones are apt to keep the manifold from bedding properly upon the used ones. It is well to coat the threads of all bolts and screws subjected to heat, such as cylinder head and exhaust manifold retaining bolts with a mixture of graphite and oil. Those that enter the water jacket should be covered with white or red lead or pipe thread compound. Gaskets will hold better if coated with shellac before the manifold or other parts are placed over them. The shellac fills any irregularities in the joint and assists materially in preventing leakage after the joint is made up and the coating has a chance to set. In replacing cylinder head packings on cars like the Ford, it is well to run the engine for a short while, several minutes at the most, without any water in the jacket in order to heat the head up thoroughly. It will usually be found possible to tighten down a little more on all of the cylinder head retaining bolts after this is done because if the gasket has been coated with shellac the sur plus material will have burrt off and the entire packing bedded Fig. 166.-Group of Parts of Cadillac Eight Cylinder V Motor, Showing Construction of Important Members of Assembly. down. Care should be taken when using shellac, white or red lead, etc., not to supply so much that the surplus will run into the cylinder, water jacket or gas passages. Loose Flywheel.-Many mysterious knocks, which are often attributed to worn bearings are due to the flywheel being loose on the shaft. In a number of the earlier forms of cars and in nearly all marine engines the flywheels are held to the shaft by a simple gib key. It often happens that these keys become worn and the wheel is slightly loose on its supporting shaft. When the engine is revolving at high speed a pronounced thump or knock will be produced because of the hammering action of the flywheel upon the loose key. The proper remedy for such a condition is to make a new key that will fit the keyways in flywheel and shaft and drive it tightly in place. In some constructions the flywheel is installed on a taper on the crankshaft and in addition to the key it is held in place by clamp nuts. These nuts sometimes become loose and permit the flywheel to back off the taper enough to produce noise. In practically all modern forms of motor the flywheel is secured to a flange forged integrally with the crankshaft by means of bolts. It may be possible for the bolts to loosen which will permit the flywheel to rock and to pound the holes out oval. This condition is easily remedied by reaming or drilling the worn holes to the next largest standard size and to fit larger bolts to correspond. Two Cycle Motors.-This form of power plant has received but limited application in automobiles, but the repairman may have occasion to investigate irregular action of some old model car using this type of motor or may be called upon to repair a marine engine of this type. It will be evident that a worn cylinder, piston rings or piston will result in the loss of compression as in any motor and that loose connecting rods or main bearings will produce noisy operation just as in the four-cycle type. In the two-cycle motors there are other conditions to be looked for besides those involving normal depreciation of the mechanism. There are two chambers to keep tight instead of one as in the four-cycle type. In the twocycle form it is not hard to maintain compression in the combustion chamber because there are no valves to leak and the only chance |