and breaks the correct register between the oil hole in the cap and brasses.

Care should be taken in screwing on the retaining nuts to insure that they will remain in place and not slack off. Spring washers should not be used on either connecting rod ends or main bearing bolts, because these sometimes snap in two pieces and leave the nut slack. The best method of locking is to use wellfitting split pins and castellated nuts. In a number of the cheaper cars, the bearing metal is cast in place in the connecting rod lower end and in main bearings, and is not in the form of removable die cast bushings as are used on the more expensive cars. The repairman who is called upon to replace the bearing metal will find the following instructions regarding remetalling bearings of value. The method described was used by the writer while in charge of a large shop where much work of this kind was done and while the instructions given apply specifically to lining the big ends of connecting rods, the same process may be used successfully on any other bearings where the mandrel and collars can be used, the dimensions being changed to suit the requirements of the worker.

In the case mentioned the journals of the crankshaft were two inches in diameter and the big ends of the connecting rods were worn too much to allow of adjusting. A piece of pipe about 9 inches long was procured and turned down in a lathe until it was a shade under 2 inches in diameter, which made a hollow mandrel of it. A piece of steel tubing could have been used to as good advantage had any been available. As the outside of the bearing caps were machined true a couple of set collars were bored out to be a good fit on the mandrel, and while still in the lathe they were recessed out to just fit over the outside of the big ends, as shown in sketch Fig. 4. One of these collars was placed on the hollow mandrel A, after which the mandrel was pushed through the big end, and. the other collar was put on the other side, insuring that the mandrel was as near center as possible for it to be.

The assemblage is then supported on a couple of V-blocks, which are supported on a lathe bed, the ends of the mandrel lying within the V's while the connecting rod hangs between the ways. A piece

Fig. 142.-Showing Simple Method of Remetalling Connecting Rod Bearings at A, and Ways of Measuring Parallelism of Upper and Lower Connecting Rod Bearings at B and C.

of solid round iron or steel which will go inside of the hollow mandrel should be made red hot while the anti-friction metal is being melted and is pushed inside the mandrel to heat it. In a minute or two the metal may be poured in through B to fill D, and as the metal and the big end caps are well heated the molten metal will flow to every point. The heating of the mandrel can be just as well accomplished by directing the flame from a blow torch or Bunsen burner into the opening. After the metal is poured and has set the whole may be easily cooled by running water through the mandrel or by directing a blast of air against the big end, as desired.

Before the cap is assembled with the connecting rod several shims or liners of sheet brass or copper should be placed between them so that adjustment for wear of the new bearing can be compensated for by the removal of a liner. As is evident, the thinner the liner and the greater the number used, the more sensitive the character of adjustment possible.

The use of a hollow mandrel is to be preferred to a solid one because of the ease with which it can be heated and cooled. Vents should be made for the heated gases by grooving the face of each of the collars nearest the big end and on the same side as the hole through which the metal is poured. If provision is not made for "venting" the molten metal will not run uniformly and will become honeycombed. After cooling the bearing is either bored out in a lathe to the size of the journal or scraped to a fit by hand. The method of pouring the molten metal is clearly shown while the sectional view makes the construction and application of the mandrel clear. The same method may be used to rebabbitt main boxes except that a pair of collars will be needed for each bearing and a long mandrel used.

Testing Bearing Parallelism.—It is not possible to give other than general directions regarding the proper degree of tightening for a connecting rod bearing, but as a guide to correct adjustment it may be said that if the connecting rod cap is tightened sufficiently so the connecting rod will just about fall over from a vertical position due to the piston weight when the bolts are fully tightened up, the adjustment will be nearly correct. As previ

ously stated, babbitt or white metal bearings can be set up more tightly than bronze, as the metal is softer and any high spots will soon be leveled down with the running of the engine. It is important that care be taken to preserve parallelism of the wrist pins and crankshafts while scraping in bearings. This can be determined in two ways. That shown at Fig. 142, B, is used when the parts are not in the engine assembly and when the connecting rod bearing is being fitted to a mandrel or arbor the same size as the crank pin. The arbor, which is finished very smooth and of uniform diameter, is placed is two V blocks, which in turn are supported by a level surface plate. An adjustable height gauge may be tried, first at one side of the wrist pin which is placed at the upper end of the connecting rod, then at the other, and any variation will be easily determined by the degree of tilting of the rod. This test may be made with the wrist pin alone, or if the piston is in place, a straight edge or spirit level may be employed. The spirit level will readily show any inclination while the straight edge is used in connection with the height gauge as indicated.

When the connecting rods are being fitted with the crankshaft in place in crankcase, and that member secured in the frame, a steel square may be used as it is reasonable to assume that the wrist pin, and consequently the piston it carries, should observe a true relation with the top of the engine base. If the piston side is at right angles with the top of the engine base it is reasonable to assume that the wrist pin and crank pin are parallel. If the piston is canted to one side or the other, it will indicate that the brasses have been scraped tapering, which would mean considerable heating and undue friction if the piston is installed in the cylinder on account of the pressure against one portion of the cylinder wall. The height gauge method shown above may be used instead of the steel square, if designed, because the top of the crank case is planed or milled true and should be parallel with the center line of the crankshaft.

On the new eight-cylinder V types of engines which are fitted on several models of 1915 cars the connecting rod design is different from that ordinarily used, as it is sometimes necessary to have two rods working from the same crank pin. The construction

follows very closely that used in motorcycle engines of the twocylinder V form. Two methods of connecting rod arrangement are shown at Fig. 143. In the example at the top of the illustration, connecting rod A has a forked end which encircles the main crank pin bushing. These ends are of the usual marine type, straddling the big end of rod B, which is free to oscil