Cylinder Head Reconditioning

CYLINDER HEAD RECONDITIONING

IMPORTANT
^ Before removing. the cylinder head(s) from the engine and before disassembling the valve mechanism, make a compression test and note the results.
^ During disassembly of the cylinder head, be sure that the valve train components are kept together and identified so that they can be installed in their original locations.

REMOVE OR DISCONNECT
1. Cylinder head engine lift hook.
2. Fuel line bracket bolts and bracket.

IMPORTANT
^ Do not remove spark plugs when hot.
^ Clean dirt and debris from spark plug recess area.

3. Spark plugs.
4. Rocker arms.
5. Remove valve locks, caps, springs, seats, oil seals, and valves.
6. Pushrod guide plates.
7. Oil galley (if equipped) and water jacket plugs.

INSPECT
^ Cylinder head gasket and mating surfaces for leaks, corrosion and blow-by. If the gasket has failed, determine the cause:
- Improper installation.
- Loose or warped cylinder head.
- Missing, off location or not fully seated dowel pins.
- Low torque on cylinder head bolts.
- Warped cylinder block surface.
- Scratched surfaces.
- Excessive intake manifold torque.
- Cracked cylinder block or tapped holes.

CLEAN

Cleaning Valve Guide:

CAUTION: Safety glasses must be worn when using a power wire brush to avoid damage to the eyes.

^ Cylinder bead bolts.
^ Cylinder head. Carefully remove all varnish, soot and carbon to the bare metal. DO NOT use a motorized wire brush on any gasket sealing surface.
^ Valve guides.
^ Threaded holes.
^ Remains of sealer from plug holes.

INSPECT

Checking Cylinder Head Flatness:

Measuring Valve Guide Clearance:

1. Cylinder head bolts for damaged threads or stretching, and damaged heads caused by improper use of tools.

IMPORTANT
^ Suspect bolts must be replaced.

2. Cylinder head for cracks, especially between valve seats and in the exhaust ports.
3. Cylinder head deck for corrosion, sand particles in head, and porosity.

IMPORTANT
^ Do not attempt to weld the cylinder head, replace it.

4. Cylinder head deck, intake and exhaust manifold mating surfaces for flatness. These surfaces may be reconditioned by milling. If the surfaces are "out of flat" by more than 0.127 mm (0.005 in.), the surface should be milled. If more than 0.25 mm (0.010 in.) of metal must be removed from the head, it should be replaced.
5. All threaded holes for damage. Threads may be reconditioned with thread inserts.
6. Water jacket plugs seating surfaces.

Valve Seat Insert:

7. Valve seats for excessive wear and burned spots.
^ Since the valve guide serves to support and center the valve grinder, it is essential that the valve guide is cleaned properly. If the valve guide requires reaming, this must be done before valve seats are reconditioned.
^ If a burnt valve condition exists, it may be necessary to recondition the valve seat insert. At no time should there be less than 4 mm of valve seat material remaining after reconditioning.
^ Valve seats may be reconditioned by grinding. Follow the grinder manufacturer's instructions. If, after grinding, the new seat is too wide, it may be narrowed by using a 70° stone. The 70° stone will raise the seat.

INSTALL OR CONNECT
1. Oil galley (if equipped) and cooling jacket plugs. Coat plugs with GM P/N 1050026 sealer or equivalent.
2. Pushrod guide plates.
3. Valves, stem oil seals, spring seats, caps and valve locks.
4. Rocker arms.

NOTICE: To avoid damage, install spark plugs after the cylinder head has been installed on the engine.

5. Spark plugs.
6. Fuel line bracket and bolts.
7. Cylinder head engine lift hook.