GM Corvette 1963-1982 Repair Guide

Cylinder Heads

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REMOVAL & INSTALLATION



See Figures 1 through 12

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Fig. Fig. 1: Exploded view of the small-block cylinder head



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Fig. Fig. 2: Exploded view of the big-block cylinder head



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Fig. Fig. 3: Always tighten the cylinder head bolts in the correct sequence to the proper torque-small-block V8 engine shown



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Fig. Fig. 4: Cylinder head bolt tightening sequence-big-block V8 engine



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Fig. Fig. 5: After removing all necessary components, unfasten the retaining bolts ...



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Fig. Fig. 6: ... then remove the rocker arm (valve) cover



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Fig. Fig. 7: Remove and discard the rocker arm (valve) cover gasket



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Fig. Fig. 8: Whenever you remove pushrods, always tag or label them for installation in their original positions



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Fig. Fig. 9: Loosen ...



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Fig. Fig. 10: ... then remove the cylinder head bolts ...



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Fig. Fig. 11: ... and separate the cylinder head from the engine block



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Fig. Fig. 12: Use a suitable torque wrench to tighten the cylinder head bolts to the proper specifications

  1. Disconnect the battery cables at the battery.
  2.  
  3. Drain the engine block of coolant by removing the drain plugs located on the engine block above the top of the oil pan.
  4.  
  5. Remove the intake manifold as described. Remove the alternator lower mounting bolt, and lay the unit aside.
  6.  
  7. Remove the exhaust manifolds. If the vehicle has A/C, dismount the compressor and position it out of the way. Do not disconnect the refrigerant lines.
  8.  
  9. Back off the rocker arm nuts and pivot the rocker arms out of the way so that the pushrods can be removed. Identify the pushrods so that they can be reinstalled in their original locations.
  10.  
  11. Remove the cylinder head bolts and cylinder heads.
  12.  
  13. Install using new gaskets. The head gasket is installed with the bead up.
  14.  

Coat a steel gasket, thinly and evenly, on both sides with sealer. If a steel asbestos gasket is used, do not apply sealer. Clean the bolt threads, apply sealing compound and install the bolts finger-tight.

  1. Tighten the head bolts a little at a time in the sequence illustrated to the specified torque.
  2.  
  3. Install the exhaust and intake manifolds.
  4.  
  5. Adjust the valves.
  6.  

OVERHAUL



See Figures 13 through 23

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Fig. Fig. 13: A C-clamp type conpressor can also be used



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Fig. Fig. 14: Check the valve spring tension



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Fig. Fig. 15: A vacuum tester is available to check the valve stem oil seals



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Fig. Fig. 16: Measure the valve spring installed height and compare with specifications



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Fig. Fig. 17: Use a gasket scraper to remove the bulk of the old head gasket from the mating surface



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Fig. Fig. 18: An electric drill equipped with a wire wheel will expedite complete gasket removal



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Fig. Fig. 19: Use a valve spring compressor tool to relieve spring tension from the valve caps



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Fig. Fig. 20: A wire wheel may be used to clean the combustion chambers of carbon deposits



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Fig. Fig. 21: A dial gauge may be used to check valve stem-to-guide clearance



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Fig. Fig. 22: Check the cylinder head for flatness across the head surface



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Fig. Fig. 23: Checks should be made both straight across the cylinder head and at both diagonals

  1. With cylinder head removed, remove valve rocker arm nuts, balls and rocker arms (if not previously done).
  2.  
  3. Using Tool J-15062, or equivalent, compress the valve springs and remove stem keys. Release the compressor tool and remove rotators or spring caps, oil shedders, springs and damper assembly, then remove oil seals and valve spring shims.
  4.  
  5. Remove valves from cylinder head and place them in a rack in their proper sequence so that they can be assembled in their original positions. Discard any bent or damaged valves.
  6.  
  7. Clean all carbon from combustion chambers and valve ports using a wire brush.
  8.  
  9. Thoroughly clean the valve guides using a suitable wire bore brush.
  10.  
  11. Clean all carbon and sludge from pushrods, rocker arms and pushrod guides. Discard bent pushrods.
  12.  
  13. Clean valve stems and heads on a buffing wheel.
  14.  
  15. Clean carbon deposits from head gasket mating surface. Be careful not to score the machined gasket surface while cleaning.
  16.  
  17. Inspect the cylinder head for cracks in the exhaust ports, combustion chambers, or external cracks to the water chamber.
  18.  
  19. Inspect the valves for burned heads, cracked faces or damaged stems.
  20.  

Excessive valve stem to bore clearance will cause excessive oil consumption and may cause valve breakage. Insufficient clearance will result in noisy and sticky functioning of the valve and disturb engine smoothness.

  1. Measure valve stem clearance as follows:
    1. Clamp a dial indicator on one side of the cylinder head rocker arm cover gasket rail.
    2.  
    3. Locate the indicator so that movement of the valve stem from side to side (crosswise to the head) will cause a direct movement of the indicator stem. The indicator stem must contact the side of the valve stem just above the valve guide.
    4.  
    5. Drop the valve head about 1 / 16 in. off the valve seat.
    6.  
    7. 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.
    8.  

  2.  

See "Valve Guide and Seat Service" for detailed overhaul procedures.

  1. Check valve spring tension with a suitable spring tester. Springs should be compressed to the specified height and checked against the specifications chart. Springs should be replaced if not within 10 lbs. (44N) of the specified load (without dampers).
  2.  
  3. Inspect rocker arm studs for wear or damage.
  4.  
  5. Check the cylinder head for warpage with a straightedge. If warpage exceeds .003 in. in a 6 in. span, or .006 in. over the total length, the cylinder head must be resurfaced (which is akin to planing a piece of wood). Resurfacing can be performed at most machine shops.
  6.  

When resurfacing the cylinder heads(s) of V8 engines, the intake manifold mounting position is altered, and must be corrected by machining a proportionate amount from the intake manifold flange.

  1. Insert a valve in the proper port.
  2.  
  3. Assemble the valve spring and related parts as follows:
    1. Set the valve spring shim, valve spring, damper assembly, 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 and release the compressor tool making sure that the valve stems seat properly in the upper groove of the valve stem. Grease may be used to hold the locks in place while releasing the compressor tool.
    8.  

  4.  
  5. Install the remaining valves, repeating assembly sequence.
  6.  
  7. Check each valve stem oil seal by placing a Leak Detector Tool J-23994, or equivalent, over the end of the valve stem and against the cap (or rotator). 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 from 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. (1.6mm) thick. At no time should the spring be shimmed to give an installed height under the minimum specified.
  10.  

 
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