Connecting Rod: Service and Repair

Fig. 17 Measuring piston diameter:

INSPECTION

1. Inspect piston for cracks or other damage. Replace as necessary.
2. Measure piston diameter at a height of .59 inches (15 mm) from piston skirt end in perpendicular direction to piston pin, Fig. 17.

Fig. 18 Measuring piston bore diameter:

3. Measure cylinder bore diameter, Fig. 18, and piston diameter to determine piston clearance. Piston clearance should be .0008-.0015 inch. If clearance is excessive, rebore cylinder and install oversize piston. All cylinders must be overbored to same size to ensure balance.

Fig. 19 Measuring piston ring side clearance:

4. With piston grooves clean, dry and free of carbon, insert piston ring into groove, and measure clearance between ring and ring land with feeler gauge, Fig. 19. If clearance is out of specification, replace piston.
5. Piston pin should fit into piston bore with easy finger push at normal room temperature. Check piston pin and piston pin bore for wear or damage. If badly worn or damaged, replace pin or piston as necessary.

Fig. 20 Measuring rod bearing side clearance:

6. Install connecting rod on its journal and check that side clearance does not exceed .0137 inch, Fig. 20. If so, replace connecting rod.

Fig. 21 Piston identification:

Fig. 22 Engine block stamping:

ASSEMBLY

Two sizes of pistons are available as standard size spare parts to ensure proper piston-to-cylinder clearance. When installing standard piston, match piston to its bore as follows:
a. Each piston has number 1 or 2 stamped on top, Fig. 21, to indicate its outside diameter.
b. The engine block is stamped as shown in Fig. 22, to indicate size of piston in each bore.

Fig. 23 Piston to connecting rod installation:

Assemble pistons, rings and rods as follows:
1. Apply engine oil to piston pin bores in piston and rod and fit connecting rod to piston as shown in Fig. 23.

Fig. 24 Piston pin installation:

2. Place piston on tool J-34838 so arrow mark on piston head faces up. Press piston pin into piston and connecting rod, Fig. 24.

Fig. 25 Piston ring installation:

3. Install piston rings so marked side of each ring faces top of piston, Fig. 25. Note shape of rings 1 and 2.

Fig. 26 Ring end gap alignment:

4. Install oil ring spacer first, then 2 rails.
5. Align ring end gaps as shown in Fig. 26. Pistons and connecting rod assemblies must be installed in block so arrows on pistons face front (pulley end) of engine.