REMOVAL & INSTALLATION
See Figures 1, 2, 3, 4 and 5
Although valve springs are normally serviced along with the valves after the cylinder head has been removed from the engine, the springs may also be removed with the cylinder head still installed if an air compressor and adapter is available. The compressed air is introduced to the combustion chamber through the spark plug fitting and is then used to hold the valves up in the cylinder head. Be careful when performing this procedure, should air pressure be lost with the valve retainers off, the valve will drop into the cylinder bore requiring cylinder head removal to retrieve it.
- If the valve springs are to be removed with the cylinder head off the engine, remove the head assembly as described earlier in this section.
- If the valve springs are to be removed with the cylinder head still on the engine, remove the cylinder head (rocker arm) cover and rocker assembly, as described earlier in this section. Position the crankshaft so the cylinder on which you are about to work is at TDC (the valves must be closed in order to hold air pressure), then install the fitting and pressurize the cylinder. Follow the fitting manufacturer's instructions, but a significant amount of the pressure is necessary.
- Using an appropriate tool, compress the valve spring until the two valve keys (keepers) can be removed from the groove in the valve head. Remove the keepers, then slowly release the spring tension. Remove the spring retainer and valve spring.
For additional piece of mind when performing this on a cylinder head which is still installed, you can tie a piece of string to the top of the valve while the spring and keepers are removed. Should air pressure be lost, the string should keep the valve from falling completely into the combustion chamber (thus preventing the need for cylinder head removal to retrieve the valve).To install:
- Position the valve spring and spring retainer over the valve stem. Compress the spring (using the same tool as in the removal procedure) until the keeper groove is fully exposed.
- Securely position the keepers in the groove, then release the spring tension, and remove the compressor tool. The spring pressure against the retainer should lock the keepers firmly in place.
See Figures 6 and 7
Inspect the valve springs for breakage or corrosion and replace as necessary. Measure the free length for conformity to specification and replace as necessary. Limits are:
On some engines, the valve springs should also be checked for straightness. Sit them flat next to a perpendicular surface and rotate each spring until there is a maximum gap between the top of the spring and the perpendicular surface. Then, measure that distance. The limits are: