REMOVAL & INSTALLATION
See Figures 1 through 7
- Remove the cylinder head from the vehicle, and place it on a clean, well lighted surface.
- Block the head on its side, or install a pair of head-holding brackets made especially for valve removal.
- Place a socket slightly larger than the valve stem and keepers over the valve stem and gently hit the socket with a plastic-faced hammer to break loose any varnish buildup.
- Remove the valve keepers, retainer, spring shield and valve spring using a valve spring compressor (the locking C-clamp type is the best for this job).
- Put the valve and spring parts in a separate container numbered for the cylinder. DO NOT mix parts from different valve assemblies.
- Remove and discard the valve stem oil seals. A new seal will be used when assembling the valves.
- Remove the lifters one at a time and number them in order. If you intend to reuse them, inspect each before reinstalling.
- Remove the valves from the cylinder head and place them in order through numbered holes punched in a stiff piece of cardboard.
The exhaust valve stems, on some engines, are equipped with small metal caps. Take care not to lose the caps. Make sure to reinstall them at assembly time. Replace any caps that are worn.
- Check the valve springs for straightness and tension.
- Install the valves in the cylinder head.
- Install new valve stem oil seals.
- Install the metal caps an the exhaust valves, if equipped.
- Install the valve keepers, retainer, spring shield and valve spring using a valve spring compressor (the locking C-clamp type is the best for the procedure).
- Check the valve spring installed height.
- Measure the distance between the spring mounting pad and the lower edge of the spring retainer. Compare the measurement to the specifications found in the Valve Specifications chart. If the installed height is incorrect, add shims between the spring mounting pad and the spring. Use only shims designed for this purpose. These are available at most automotive parts stores.
VALVE SPRING INSPECTION
See Figure 8
Place the valve spring on a flat surface next to a carpenter's square. Measure the height of the spring, and rotate the spring against the edge of the square to measure distortion. If the spring height varies (by comparison) by more than 1 / 16 in. (1.6mm) or if the distortion exceeds 1 / 16 in. (1.6mm), replace the spring.
Have the valve springs tested for spring pressure at the installed and compressed (installed height minus valve lift) height using a valve spring tester. Springs should be within one pound, plus or minus each other. Replace springs as necessary.
See Figures 9 and 10
Because of exact tolerances required of valve surfaces, and the specialized tools, which are not readily available at most automotive stores, needed to perform valve refacing, it is recommended that you consult a professional machine shop when it comes to valve refacing
- If necessary, have the valves and valve seats refaced. The valve seats should be a true 45º angle. Remove only enough material to clean up any pits or grooves. Be sure the valve seat is not too wide or narrow. Use a 60º grinding wheel to remove any material from the bottom of the seat and a 30º grinding wheel to remove material from the top of the seat.
- After the valves are refaced by machine, hand lap them to the valve seat. Clean the grinding compound off and check the position of face-to-seat contact. Contact should be close to the center of the valve face. If contact is close to the top edge of the valve, narrow the seat; if too close to the bottom edge, raise the seat.
- Valves should be refaced to a true angle of 44º. Remove only enough metal to clean up the valve face or to correct runout. If the edge of a valve head, after machining, is 1 / 32 in. (0.8mm) or less replace the valve. The tip of the valve stem should also be dressed on the valve grinding machine. However, do not remove more than 0.010 in. (0.254mm).
HYDRAULIC LIFTER INSPECTION
See Figure 11
Remove the lifter(s) from their bore(s) and remove any gum and/or varnish with a safe solvent. Check the lifters for concave wear. If the bottom of the lifter is worn concave or flat, replace the lifter. Lifters are built with a convex bottom. Any flatness would indicate wear. If a worn lifter is detected, carefully inspect the camshaft.
When removing lifters, mark them cylinder location. Lifters must be reinstalled in the same bore from which they were removed.
To test lifter leak down, submerge the lifter in a container of kerosene. Chuck a used pushrod that will not be reused or its equivalent into a drill press. Position the container of kerosene so the pushrod acts on the lifter plunger. Pump the lifter with the drill press until resistance increases. Pump several more times to bleed any air from the lifter. Apply very firm, constant pressure to the lifter and observe the rate which fluid bleeds out of the lifter. If the lifter bleeds down very quickly (less than 15 seconds), the lifter should be replaced. If the time exceeds 60 seconds, the lifter is sticking and should be cleaned or replaced. If the lifter is operating properly (leak down time 15-60 seconds) and is not worn, lubricate and reinstall it in the engine.
It is always better to replace a lifter than trying to clean it. Replace the complete set of lifters instead of one or two when performing this repair.