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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1018 (Engine Mechanical - 4.3L) >> Repair Instructions >> Off-Vehicle Repair Instructions >> Piston, Connecting Rod, and Bearing Installation >> Piston Selection

Piston Selection

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: Measurements of all components should be taken with the components at normal room temperature.
    For proper piston fit, the engine block cylinder bores should not have excessive wear or taper.
    A used piston and piston pin set may be reinstalled if, after cleaning and inspection, the piston and piston pin are within specifications.
  1. Use the J 8087 in order to measure the cylinder bore diameter. Measure at a point 64 mm (2.5 in) from the top of the cylinder bore and 90 degrees to the crankshaft centerline.
    2. Fig 1: Measuring Cylinder Bore
    GM4972Courtesy of GENERAL MOTORS CORP.
  2. Measure the J 8087 with a micrometer and record the reading.
    3. Fig 2: Measuring Bore Gauge With Micrometer
    GM4974Courtesy of GENERAL MOTORS CORP.
  3. With a micrometer or caliper at a right angle to the piston pin bore, measure the piston 11 mm (0.433 in) from the bottom of the skirt.
    4. Fig 3: Measuring Piston Outside Diameter Using Micrometer
    GM188016Courtesy of GENERAL MOTORS CORP.
  4. Subtract the piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance. Refer to Engine Mechanical Specifications .
  5. If the proper clearance cannot be obtained, then select another piston and measure the clearances.

    If the proper fit cannot be obtained, the cylinder bore may require honing or boring.

  6. When the piston-to-cylinder bore clearance is within specifications, permanently mark the top of the piston for installation into the proper cylinder.
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