Standard Procedure - Piston Fitting

WARNING: This page is about a different car, the 2008 Dodge Magnum, 2008 Dodge Charger, and 2008 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.

To correctly select the proper size piston, a cylinder bore gauge, capable of reading in 0.003 mm (0.0001 in.) INCREMENTS is required. If a bore gauge is not available, do not use an inside micrometer.
Measure the inside diameter of the cylinder bore at a point 38.0 mm (1.5 inches) below top of bore. Start perpendicular (across or at 90 degrees) to the axis of the crankshaft at point A and then take an additional bore reading 90 degrees to that at point B. See Fig 2.
NOTE: Always install new retaining clips for the piston pin. Never reuse the old clips.

NOTE: Use care not to distort the clip while installing.

Once assembled, the piston-rod assembly is specific for the left cylinder bank (odd numbered) and the right cylinder bank (even numbered) and must not be interchanged.

Fig 1: Moly Coated Piston

Courtesy of CHRYSLER LLC

1 - MOLY COATED

2 - MOLY COATED

Fig 2: Bore Gauge Typical

Courtesy of CHRYSLER LLC

1 - FRONT

2 - BORE GAUGE

3 - CYLINDER BORE

4 - 38 MM
(1.5 in)

The coating material is applied to the piston after the final piston machining process. Measuring the outside diameter of a coated piston will not provide accurate results. See Fig 1. Therefore measuring the inside diameter of the cylinder bore with a dial Bore Gauge is MANDATORY . To correctly select the proper size piston, a cylinder bore gauge capable of reading in 0.003 mm (0.0001 in.) increments is required.
Piston installation into the cylinder bore requires slightly more pressure than that required for non-coated pistons. The bonded coating on the piston will give the appearance of a line-to-line fit with the cylinder bore.