REMOVAL & INSTALLATION
See Figures 1 through 7
- Refer to the Cylinder Head, Removal & Installation and the Camshaft, Removal & Installation procedures in this section, then, remove the cylinder head from the engine and the camshaft from the cylinder head.
- Using a plastic mallet, tap each valve stem to loosen the valve keepers.
- Using a Valve Spring Compressor tool, compress the valve springs, then, remove the valve keepers, retainers and springs. Remove the valves from the opposite side of the cylinder head.
When removing the valves and components, keep them in order for reinstallation purposes.
- To replace the valve seals, simply pull the seal from the valve guide. If the valve seals are being reused, it is good idea to replace the springs around the seal's neck.
The exhaust valve seal uses a black spring, while the intake valve seal uses a white spring.
- Inspect the valves for wear, damage and/or cracks. If necessary, reface the valves on a valve grinding machine.
When replacing the valve springs, place the closely wound end toward the cylinder head.
- To assemble the cylinder head, use new valve seals, lubricate the valve parts with clean engine oil and reverse the disassembly procedures. After removing the valve spring compressor, tap the valve stems 2-3 times to make sure the valve keepers and valves are fully seated.
- To complete the installation, use new gaskets and reverse the removal procedures.
Inspect the valve faces and seats (in the head) for pits, burned spots and other evidence of poor seating. If a valve face is in such bad shape that the head of the valve must be ground, in order to true the face, discard the valve, because the sharp edge will run too hot. The correct angle for valve faces is 45°. We recommend the refacing be performed by a reputable machine shop.
Check the valve stem for scoring and burned spots. If not noticeably scored or damaged, clean the valve stem with solvent to remove all gum and varnish. Clean the valve guides using and an expanding wire-type valve guide cleaner. If you have access to a dial indicator for measuring valve stem-to-guide clearance, mount it so the stem of the indicator is at 90° to the valve stem and as closer to the valve guide as possible. Move the valve off its seat, then, measure the valve guide-to-stem clearance by rocking the stem back and for the actuate the dial indicator. Measure the valve stem diameter using a micrometer and compare it to specifications to determine whether the stem or guide wear is responsible for the excess clearance. If a dial indicator and micrometer are not available, take the cylinder head and valves to a reputable machine shop for inspection.
All valve grinding operations should be performed by a qualified machine shop; ONLY the valve lapping operation is recommended to be performed by the inexperienced mechanic.Valve Lapping
See Figure 8
When valve faces and seats have been refaced and/or recut, or if they are determined to be in good condition, the valves MUST BE lapped in to ensure efficient sealing when the valve closes against the seat.
- Invert the cylinder head so the combustion chambers are facing upward.
- Lightly lubricate the valve stems with clean engine oil and coat the valve seats with valve grinding compound. Install the valves in the cylinder head as numbered.
- Using a valve lapping tool, attach the suction cup to a valve head. You will probably have to moisten the suction cup to securely attach the tool to the valve.
- Rotate the tool between the palms, changing position and lifting the tool often to prevent grooving. Lap the valve until a smooth polished seat is evident (you may have to add a bit more compound after some lapping is done).
- Remove the valve and tool, then, remove all traces of the grinding compound with a solvent-soaked rag or rinse the head with solvent.
Valve lapping can also be done by fastening a suction to a piece of drill rod in a hang egg-beater type drill. Proceed as above, using the drill as a lapping tool. Due to the higher speeds involved when using the hand drill, care must be exercised to avoid grooving the seat. Lift the tool and change direction of rotation often.