Piston & Rod Assembly
WARNING: This page is about a different variant/trim than selected.
CAUTION:
DO NOT substitute old style pistons for new coated pistons. New coated pistons are supplied pre-assembled with piston, piston pin and connecting rod as a unit and must be replaced as a complete set. New coated piston/connecting rod assembly can be used to service older engines, but must be replaced as complete sets.
- To correctly select proper size piston, a Cylinder Bore Gauge (6879), capable of reading in .0001" (.003 mm) increments with Gauge Ring (6884) is required. If a suitable dial bore gauge is not available, DO NOT substitute an inside micrometer.
- Using gauge ring, zero dial bore gauge. Using dial bore gauge, measure cylinder bore and record readings. Measure cylinder bore 3/8" (10 mm) below top of bore in line with axis of crankshaft ("A"). Take a second reading at 90 degrees to first reading ("B"). Perform same measurements at middle of bore, and 3/8" (10 mm) from bottom of bore.
- Recheck zero of bore gauge in gauge ring. If gauge does not read zero, reset and repeat measurements.
- Measuring inside diameter of cylinder bore with a .0001" (.003 mm) reading dial bore gauge is mandatory to obtain correct clearance. See CYLINDER BORE & PISTON IDENTIFICATION table. Piston installation into cylinder bore requires slightly more pressure than for non-coated pistons. Coating will give appearance of a 0-0 fit in cylinder bore.
NOTE:
New coating material is applied to the piston after final machining process. Measuring outer diameter of a coated piston will not provide accurate results.
CYLINDER BORE & PISTON IDENTIFICATION
| Bore Size | Piston ID |
|---|---|
| 3.8755-3.8759" | "A" |
| 3.8759-3.8763" | "B" |
| 3.8763-3.8767" | "C" |
| 3.8767-3.8771" | "D" |
| 3.8771-3.8775" | "E" |
| 3.8775-3.8779" | "F" |