Chevrolet Full-size Cars 1968-1978 Repair Guide

Cylinder Head

Print

REMOVAL & INSTALLATION





Click image to see an enlarged view

Fig. Fig. 1 Exploded view of the cylinder head and related components for the small block Chevrolet V8 engine



Click image to see an enlarged view

Fig. Fig. 2 Exploded view of the cylinder head and related components for the big block Chevrolet V8 engine

The engine should be overnight cold before the cylinder head is removed to prevent warpage.

Inline 6-Cylinder Engine


Click image to see an enlarged view

Fig. Fig. 3 Cylinder head torque sequence for inline six-cylinder engines

  1. Disconnect the negative battery cable.
  2.  
  3. Drain cooling system. Remove air cleaner and disconnect the PCV hose.
  4.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Disconnect accelerator pedal rod at the bellcrank on the manifold, the fuel and the vacuum lines at the carburetor.
  2.  
  3. Disconnect the exhaust pipe at the manifold flange, then remove the manifold bolts, the clamps, the manifolds and the carburetor as an assembly.
  4.  
  5. Remove the fuel and the vacuum line retaining clip from the water outlet. Disconnect the wiring harness from the temperature sending unit and the coil, leaving the harness clear of the clips on the rocker arm cover.
  6.  
  7. Disconnect the radiator hose at the water outlet housing and the negative battery cable from the cylinder head.
  8.  
  9. Disconnect the wires and remove the spark plugs.
  10.  
  11. Remove the rocker arm cover, then back off the rocker arm nuts. Pivot the rocker arms to clear the pushrods and remove the pushrods.
  12.  
  13. Remove the cylinder head bolts, the cylinder head and the gasket.
  14.  
  15. Using a gasket scraper, clean the gasket mounting surfaces.
  16.  

To install:

  1. Using a new gasket, position the head on the block. Oil the cylinder head bolts and install them. Torque the cylinder head bolts a little at a time using the torquing sequence.
  2.  
  3. Install the pushrods. Pivot the rocker arms over the pushrods, then tighten the rocker arm nuts.
  4.  
  5. Adjust the valves.
  6.  
  7. Install the rocker arm cover.
  8.  
  9. Install the spark plugs and wires.
  10.  
  11. Connect the radiator hose at the water outlet housing and the negative battery cable at the cylinder head.
  12.  
  13. Install the fuel and vacuum line retaining clip at the water outlet. Connect the wiring harness at the temperature sending unit and the coil.
  14.  
  15. Install the manifolds and the carburetor as an assembly. Connect the exhaust pipe at the manifold flange.
  16.  
  17. Connect accelerator pedal rod at the bellcrank on the manifold, the fuel and the vacuum lines at the carburetor.
  18.  
  19. Fill cooling system.
  20.  
  21. Install air cleaner.
  22.  
  23. Connect the PCV hose.
  24.  
  25. Connect the negative battery cable.
  26.  

V8 Engines


Click image to see an enlarged view

Fig. Fig. 4 Cylinder head torque sequence for small block Chevrolet V8 engines



Click image to see an enlarged view

Fig. Fig. 5 Cylinder head torque sequence for big block Chevrolet V8 engines



Click image to see an enlarged view

Fig. Fig. 6 To remove the cylinder head(s) on V8 engines, remove the intake manifold ...



Click image to see an enlarged view

Fig. Fig. 7 ... followed by the exhaust manifold(s), rocker cover(s) and rocker arms



Click image to see an enlarged view

Fig. Fig. 8 To help keep the pushrods in order, make up a simple pushrod holder out of a piece of cardboard



Click image to see an enlarged view

Fig. Fig. 9 Loosen and remove the cylinder head bolts according to the proper sequence



Click image to see an enlarged view

Fig. Fig. 10 Pull the cylinder head off of the cylinder block-an assistant may be helpful since the heads are heavy



Click image to see an enlarged view

Fig. Fig. 11 With the cylinders and lifter valley shielded from debris, remove the old gaskets and discard them



Click image to see an enlarged view

Fig. Fig. 12 Scrape the cylinder head and block surfaces, and wipe them free of any grease, oil or grit



Click image to see an enlarged view

Fig. Fig. 13 When installing the cylinder head, tighten the bolts in the proper sequence to the indicated torque



Click image to see an enlarged view

Fig. Fig. 14 A wire wheel may be used to clean the combustion chambers of carbon deposits



Click image to see an enlarged view

Fig. Fig. 15 Use a gasket scraper to remove the bulk of the old head gasket from the mating surface



Click image to see an enlarged view

Fig. Fig. 16 An electric drill equipped with a wire wheel will expedite complete gasket removal



Click image to see an enlarged view

Fig. Fig. 17 Check the cylinder head for warpage along the center using a straightedge and a feeler gauge



Click image to see an enlarged view

Fig. Fig. 18 Be sure to check for warpage across the cylinder head at both diagonals

  1. Remove the intake manifold.
  2.  
  3. Remove the alternator's lower mounting bolt and move the unit aside.
  4.  
  5. Remove the exhaust manifolds, the rocker arm covers and the rocker arm assemblies. Remove the pushrods.
  6.  
  7. As required, remove the air injection manifold assemblies. Drain the cooling system.
  8.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Remove the diverter valve, if equipped. Remove the cylinder head bolts and the cylinder heads from the engine.
  2.  
  3. Installation is the reverse of the removal procedure.
  4.  
  5. Clean the cylinder head bolts and coat the threads with RTV sealant.
  6.  
  7. Be sure to use new gaskets or RTV sealant, as required. Torque the cylinder head bolts to specification and in the proper sequence.
  8.  

CLEANING & INSPECTION



Chip carbon away from the valve heads, combustion chambers, and ports, using a chisel made of hardwood. Remove the remaining deposits with a stiff wire brush.

Be sure that the deposits are actually removed, rather than burnished. Have the cylinder head hot-tanked to remove grease, corrosion, and scale from the water passages. Clean the remaining cylinder head parts in an engine cleaning solvent. Do not remove the protective coating from the spring.

Place a straightedge across the gasket surface of the cylinder head. Using feeler gauges, determine the clearance at the center of the straightedge. If warpage exceeds 0.003 in. in a 6 in. span, or 0.006 in. over the total length, the cylinder head must be resurfaced.

If warpage exceeds the manufacturer's maximum tolerance for material removal, the cylinder head must be replaced. When milling the cylinder heads of V-type engines, the intake manifold mounting position is altered, and must be corrected by milling the manifold flange a proportionate amount.

RESURFACING



This procedure should only be performed by a machine shop.

 
label.common.footer.alt.autozoneLogo