1942 - 1947 Chevrolet Shop Manual



	6-16

	This can be done with the dial indicator as shown in Fig. 30. The face and rim of the flywheel should not exceed .008" run-out. CONNECTING RODS Chevrolet connecting rods are made of special steel, drop forged and of unusual strength. The connecting rod bearings are of the "spun-in" type. By this is meant that the babbitt lining or bearing part is an integral part of the rod assembly. The metal is not simply poured or die cast into place. Instead, the rod and cap forgings are clamped to a special face plate which revolves at a high rate of speed. The centrifugal action set up causes the molten metal to be forced out towards the walls of the rod, and, in cooling becomes practically a part of the connecting rod. The connecting rods are then checked for alignment, weighed and go through a series of other important dimension checks. The rods that pass this very careful inspection are then placed in new engines or sent out for service. Every time a connecting rod is removed and is	to be replaced in an engine, or a new connecting rod is to be installed, it should be carefully checked for alignment on a connecting rod alignment fixture. Connecting Rod Alignment The connecting rod alignment fixture, Fig. 31. is used to accurately check the alignment of the piston and pin with the connecting rod bearing. The connecting rod is clamped on the arbor, as shown in the illustration, and by use of the "V" block resting against either the piston or the piston pin, the amount of misalignment will be shown between the pins on the "V" block and the face plate on the fixture. To check the rod on this fixture, place the pin in the rod and assemble the rod and pin to the arbor on the fixture. Place the "V" block on the piston pin, and move the rod and arbor toward the face plate. The vertical pins will indicate a cocked or bent rod. By that it is meant that if the two top pins rest against the face plate and the two bottom pins are away from the face plate, the rod is cocked or bent. The same is true if the two bottom pins rest against the face plate and the two top pins are away from it. If the two horizontal pins, on the front side, rest against the face plate and the two hack pins are away from it, the rod is twisted. The same is true if the two back pins rest against the face plate and the two front pins are away from the face plate. The fixture is sufficiently strong to hold the connecting rod, if straightening is necessary, which can be done with a bending bar. After this check has been made and the rod straightened, if necessary, so that all four pins touch the face plate, the "V" block should be placed on the piston pin so that the "V" block rests against the outside edge of the connecting rod and then the rod and "V" block is moved toward the face plate until all four pins touch. The index, on the bottom of the fixture, is then placed so that it touches the large end of the connecting rod bearing. Remove the rod from the arbor and turn it around. Assemble it again to the arbor and place the "V" block on the piston pin in the same place as when checking the other side. Move rod and "V" block toward the face plate until either the index touches the bearing or the pins touch the face plate. If the index does not touch the rod bearing with the four pins touching the face plate, the distance between the rod bearing and the index should be checked with a feeler gauge. If this distance is more than .025" the rod should be straightened until both the pins touch the face plate and the index touches the rod bearing, within .025".

	Fig. 31—Connecting Rod Alignment Fixture