GM Cutlass RWD 1970-1987 Repair Guide

Valves

Imprimir

All valve reconditioning procedures should be performed by a competent machine shop.

The equivalents of the special tools mentioned in the following procedures may be used.

REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6 and 7

  1. Remove the cylinder head(s), and place on a clean surface.
  2.  
  3. Using suitable spring compressor, Buick and Chevrolet built engines require the use of tool J-8062 or equivalent. Oldsmobile built engines require the use of tool J-5892 or equivalent, compress valve spring and remove valve spring cap key. Release tool and remove spring and cap. If the springs will not release, tap on the valve cap with a brass hammer with the compressor removed
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Fig. Fig. 1: Using a spring compressor, compress valve spring and remove the valve key with the help of a small magnet



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Fig. Fig. 2: Remove the valve spring

  1. Remove valve seals from intake valve guides. Seals must be discarded.
  2.  
  3. Slide valves out of the head from the combustion chamber side.
  4.  
  5. Make a holder for the valves out of a piece of wood or cardboard, as outlined for the pushrods in Cylinder Head Removal. Make sure you number each hole in the cardboard to keep the valves in proper order. Slide the valves out of the head from the combustion chamber side; they MUST be installed as they were removed.
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Fig. Fig. 3: Remove the valve seals from the intake valve guides, (throw these seals away as you'll be installing new seals)



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Fig. Fig. 4: Remove the valve stem seal from the cylinder head



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Fig. Fig. 5: Invert the cylinder head and withdraw the valve from the cylinder head bore

To install:
  1. Insert a valve in the proper port.
  2.  
  3. Assemble the valve spring and related parts as follows:
    1. Set the valve spring (with damper) oil shedder and valve cap or rotator in place.
    2.  
    3. Compress the spring with Tool J-8062 or equivalent.
    4.  
    5. Install oil seal in the lower groove of the stem, making sure that the seal is flat and not twisted.
    6.  
    7. Install the valve locks and release the compressor tool, making sure that the locks seat properly in the upper groove of the valve stem.
    8.  

  4.  
  5. Install the remaining valves.
  6.  
  7. Check each valve stem oil seal by placing Valve Seal Leak Detector (Tool J-23994) over the end of the valve stem and against the cap. Operate the vacuum pump and make sure no air leaks past the seal.
  8.  
  9. Check the installed height of the valve springs, using a narrow thin scale. A cutaway scale will help. Measure form the top of the shim or the spring seat to the top of the oil shedder. If this is found to exceed the specified height, install a valve spring seat shim approximately 1 / 16 in. thick, At no time should the spring be shimmed to give an installed height under the minimum specified.
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Fig. Fig. 6: With the valves removed, a wire wheel may be used to clean the combustion chambers of carbon deposits



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Fig. Fig. 7: Removing valve spring - Oldsmobile built engines

INSPECTION



See Figures 8, 9 and 10

  1. Remove all carbon from combustion chambers, piston heads, and valves. When using scrapers or wire brushes for removing carbon, avoid scratching valve seats and valve faces. A soft wire brush is suitable for this purpose.
  2.  
  3. Use a reamer to clean carbon and gum deposits from valve guide bores.
  4.  
  5. Inspect valve faces and seats for pits, burned sports or other evidences of poor seating. If a valve head must be ground until the outer edge is sharp in order to true up the face, discard the valve because the sharp edge will run too hot.
  6.  
  7. If valve stem has too much clearance in its guide, the guide should be reamed.
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Fig. Fig. 8: A dial gauge may be used to check valve stem-to-guide clearance



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Fig. Fig. 9: Use a micrometer to measure the valve stem diameter



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Fig. Fig. 10: Valve stems may be rolled on a flat surface to check for bends

Measuring Valve Stem Height

See Figure 11

Whenever a new valve is installed, or after grinding valves, it will be necessary to measure valve stem height as follows:

  1. Install gauge J-5289. There should be at least 0.015 in. (0.381mm) clearance on all valves between gauge surface and end of the valve stem. (Valve stem can be gauged with or without the valve rotator on the valve).
  2.  
  3. If clearance is less then 0.015 in. (0.381mm), remove valve and grind tip of valve stems as required on a valve refacing machine.
  4.  
  5. Using the V - block attachment to insure a smooth 90° end. Also be certain to break sharp edge on ground valve tip. Observe an original valve to determine chamfer.
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  7. After all valve keys have been installed on valves, tap each valve stem end with a mallet to seat valve rotators and keys.
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  9. Using gauge J-5289 re-gauge all valves between valve stem and gauge (0.015 in./0.381mm, minimum) and valve rotator and gauge (0.030 in./0.762mm, minimum). If any valve stem end is less then 0.005 in. above rotator, the valve is too short and a new valve must be installed.
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Fig. Fig. 11: Measuring valve stem height - Oldsmobile built engines

Valve Stem Clearance

Measure valve stem clearance as follows:

  1. Clamp a dial indictor on one side of the cylinder head rocker arm cover gasket rail, locating the indictor so that movement of the valve stem from side to side (crosswise to the head) will cause a direct movement of the indictor stem.
  2.  
  3. The indictor stem must contact the side of the valve stem just above the valve guide. With the valve head dropped about 1 / 16 in. off the valve seat; move the stem of the valve from side to side using light pressure to obtain a clearance reading. If clearance exceeds specifications it will be necessary to ream valve guides for oversize valves. Service valves are available in standard, 0.003 in. (0.0762mm), 0.015 in. (0.381mm) and 0.030 in. (0.762mm) oversize.
  4.  

Checking Rotators

See Figure 12

The rotators cannot be disassembled and require replacement only when they fail to rotate the valve.

Rotator action can be checked by applying a daub of paint across the top of the body and down the collar. Run engine approximately 1,500 rpm. There should appear to be motion between the body and collar; the body will appear to walk around the collar. Rotator action can be either clockwise or counterclockwise. Sometimes, on removal and reinstallation, the direction of rotation will change but this does not matter so long as it rotates.

Any time the valves are removed for service, the tips should be inspected for improper pattern which could indicate valve rotator malfunction.



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Fig. Fig. 12: Measuring rotor height - Oldsmobile built engines