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Home >> Geo >> 1991 >> Prizm Base, 4D Hatchback, Standard >> Repair and Diagnosis (Single Page) >> Engine Mechanical >> Mechanical >> 1.6L 4-CYL - VINS [5,6] >> Adjustments >> Valve Clearance Adjustment

Valve Clearance Adjustment

NOTE: Adjust valve clearance with engine cold.
  1. Disconnect negative battery cable. Disconnect all necessary control cables, hoses and electrical connections. Remove valve cover(s) and gasket.
  2. Rotate crankshaft so No. 1 cylinder is at TDC of compression stroke. Ensure timing mark on crankshaft pulley aligns with "0" mark on timing belt cover.
  3. Using feeler gauge, check clearance between camshaft lobe and adjusting shim for the following: all valves on No. 1 cylinder, intake valves on No. 2 cylinder, and exhaust valves on No. 3 cylinder. Record all readings.
  4. Rotate crankshaft 360 degrees. Check clearance between camshaft lobe and adjusting shim for the following: all valves on No. 4 cylinder, intake valves on No. 3 cylinder, and exhaust valves on No. 2 cylinder. If clearance is not within specification, adjust by replacing adjusting shim. See VALVE CLEARANCE SPECIFICATIONS table.
    VALVE CLEARANCE SPECIFICATIONS

    Application Clearance: In. (mm)
    Exhaust (1) .008-.012 (.20-.30)
    Intake (1) .006-.010 (.15-.25)
    (1) Adjust valve clearance with engine cold.
  5. Rotate engine until camshaft lobe faces away from valve to be adjusted. Insert Valve Spring Depressor (J-37141-1) between camshaft and adjusting shim. See Fig 1 .
  6. Install Valve Lash Spring Spacer (J-37141-2A) between camshaft and valve lifter. Ensure bottom edge of valve lash spring spacer contacts valve lifter, NOT adjusting shim. Remove valve spring depressor. Using small screwdriver and magnet, remove adjusting shim from valve lifter.
    Fig 1: Adjusting Valve Clearance
    G91G00410Courtesy of GENERAL MOTORS CORP.
  7. Measure thickness of removed shim. Determine correct thickness of adjusting shim to be used by subtracting appropriate valve clearance specification (see VALVE CLEARANCE SPECIFICATION Table) from measured valve clearance. Add this number to thickness of old shim. Select a new shim with a thickness as close as possible to the calculated value. See SHIM THICKNESS Table.
  8. Install correct shim thickness to obtain proper clearance. See VALVE CLEARANCE SPECIFICATIONS table. Repeat procedure as necessary. Before installing valve cover, apply Sealant (1052751) at valve cover-to-camshaft bearing cap and cylinder head surfaces. Install valve cover in reverse order of removal.
SHIM THICKNESS

Thickness mm (In.) Shim No.
2.50 (0.0984) 02
2.55 (0.1004) 04
2.60 (0.1024) 06
2.65 (0.1043) 08
2.70 (0.1063) 10
2.75 (0.1083) 12
2.80 (0.1102) 14
2.85 (0.1122) 16
2.90 (0.1142) 18
2.95 (0.1161) 20
3.00 (0.1181) 22
3.05 (0.1201) 24
3.10 (0.1220) 26
3.15 (0.1240) 28
3.20 (0.1260) 30
3.25 (0.1280) 32
3.30 (0.1299) 34
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