How To Pour Connecting Rod Babbitt Bearings

| September/October 1981

Worn out or missing connecting rod bearings are frequently a problem with old engines. Sometimes it is possible to locate bearings to fit, but it is costly and takes a long time.

With a minimum of equipment, a cast iron pot and a ladle, that may be procured at a flea market for $15.00 or $20.00, you may pour your own bearings.

It takes a little ingenuity to make a fixture to hold your old connecting rod, but the fixture can be made from wood. Note the crude example, though entirely effective, in the photo. Babbitt is available from old engine suppliers and some local auto parts stores. It costs about $4.00 a pound, which is sufficient for most bearings. The wood fixture you see here was made from a piece of 2' X 4', about 20' long, and a piece of 1' X 4', about 6' long.

The bearing for this rod needed a flange on both sides of the bearing. It is necessary to measure the outside diameter of the rod casting. Drill a hole, slightly smaller than this diameter near one end of the 2' X 4' block. It should only be drilled about 1/8' deep, using a hole saw. The inside of this hole must be cleaned out with a wood chisel. The connecting rod journal diameter has been measured, assuming it is 1.250' in diameter, locate a shaft of this diameter, you will need a short piece, perhaps six inches long. Drill a hole, this size precisely, in the center of the large hole drilled in the 2' X 4' block. It need be only about one inch deep. This hole will support the dummy shaft. Next, a hole is drilled in the 1' X 4' block the same diameter as the large hole in the 2' X 4' block. Drill all the way through this piece. This piece will be placed over the connecting rod, to hold it in place, and form the flange on the other side of the bearing.

The connecting rod is now checked for shims. I usually add a sixteenth of an inch shims or more, between the cap and rod of the connecting rod. The pieces are smoothed with a file, assembled, bolted in place, and any openings are plugged with wood. The rod is now placed on the block, checked for centering over the shaft and aligned with the large opening. I usually drive nails on both sides to hold it in position. The wrist pin end of the rod is then checked to see if it is level with the big end of the rod. It is usually necessary to shim under the rod to make it level. (Note the piece of wood in the photo.)

The 1' X 4' piece of wood is then placed over the big end of the rod and centered. This piece is then attached with two wood screws to the 2' X 4' block to hold the rod in position. Check the fixture again for perfect alignment. It is advisable to use a bevel protractor. (Note the use in the photo.)