Figure 6-2. Checking Piston to Cylinder Fit

TM 10-3930-623-34

Figure 6-2. Checking Piston to Cylinder Fit

6-20. CONNECTING ROD BEARING. Check fit of

4. Connecting rod piston pin to crankshaft bore

piston pin (18, figure 4-28) in connecting rod bearing

must be parallel. Check for maximum of 0.002 inch twist

(23). See figure 7-1 for specifications. If clearance is

or out of squareness spread over 4.0 inches.

excessive, using an arbor press and suitable support

Connecting rod may be bent or twisted to meet

press out worn bearing and press in new one in one

specifications.

operation using the new bearing as a driver (figure 6-3).

Bearing must be honed on a honing machine to obtain

6-22. PISTON RING INSTALLATION.

proper fit.

1. Using piston ring expander tool, install three

NOTE

piece oil control ring (14 and 15, figure 4-28) in lower

The piston pin must be a tight fit to

groove of piston (16). End gaps of steel segment ring

the piston and have clearance in the

should be 90 deg. in each direction from the expander

connecting rod.

spacer end gap.

CONNECTING ROD REASSEMBLY.

6-21.

facilitate assembly of piston and piston pin, piston must

2. Install third and second groove compression

be heated and assembled as follows:

rings (13) and top compression ring (12).

1. Using an oven or hot oil bath (160 deg F) heat

piston (16, figure 4-28) for 20 minutes.

2. Quickly assemble piston and mating connecting

rod (20).

NOTE

Each piston and connecting rod must

be returned to the cylinder from

which it was removed. in addition

both must face in same direction as

indicated by the word "front" on

pieces or as marked when removed.

3. Piston pin (18) can be lightly tapped to pass it

through piston and rod.

Figure 6-3. Pressing Out Old Piston Pin Bearing With

New Bearing

6-4