HEIGHT AND PRESSURE CHECK
See Figures 1, 2, 3 and 4
- Place the valve spring on a flat, clean surface next to a square.
- Measure the height of the spring, and rotate it against the edge of the square to measure distortion (out-of-roundness). If spring height varies between springs by more than 1 / 16 in. (1.5mm) or if the distortion exceeds 1 / 16 in. (1.5mm), replace the spring.
A valve spring tester is needed to test spring test pressure, so the valve springs must usually be taken to a professional machine shop for this test. Spring pressure at the installed and compressed heights is checked, and a tolerance of plus or minus 5 lbs. is permissible on the springs covered in this guide.
See Figure 5
New valve seals must be installed when the valve train is put back together. Certain seals slip over the valve stem and guide boss, while others require that the boss be machined. In some applications Teflon guide seals are available. Check with a machinist and/or automotive parts store for a suggestion on the proper seals to use.
Remember that when installing valve seals, a small amount of oil is able to pass the seal to lubricate the valve guides; otherwise, excessive wear will result.To install the valves and rocker assembly:
- Lubricate the valve stems with clean engine oil.
- Install the valves in the cylinder head, one at a time, as numbered.
- Lubricate and position the seals and valve springs, again a valve at a time.
- Install the spring retainers, and compress the springs.
- With the valve key groove exposed above the compressed valve spring, wipe some wheel bearing grease around the groove. This will retain the keys as you release the spring compressor.
- Using needlenose pliers (or your fingers), place the keys in the key grooves. The grease should hold the keys in place. Slowly release the spring compressor; the valve cap or rotator will raise up as the compressor is released, retaining the keys.
- Install the rocker assembly, and install the cylinder head(s).
VALVE LASH ADJUSTMENT
Most engines described in this guide use hydraulic lifters, which require no periodic adjustment. In the event of cylinder head removal or any operation that requires disturbing the rocker arms, the rocker arms will have to be adjusted.Hydraulic Lifters
- Remove the cylinder head covers and gaskets.
Adjust the valves as follows:
- Crank the engine until the mark on the damper aligns with the TDC or 0 mark on the timing tab and the engine is in the No. 1 firing position. This can be determined by placing the fingers on the No. 1 cylinder valves as the marks align. If the valves do not move, it is in the No. 1 firing position. If the valves move, it is in the No. 6 firing position (No. 4 and V6) and the crankcase should be rotated one more revolution to the No. 1 firing position.
- Back out the adjusting nut until lash is felt at the pushrod, then turn the adjusting nut in until all lash is removed. This can be determined by checking pushrod end-play while turning the adjusting nut. When all play has been removed, turn the adjusting nut in 1 full turn.
- With the engine in the No. 1 firing position, the following valves can be adjusted:
- V8 Exhaust: 1, 3, 4, 8
- V8 Intake: 1, 2, 5, 7
- V6 Exhaust: 1, 5, 6
V6 Intake: 1, 2, 3
- Crank the engine 1 full revolution until the marks are again in alignment. This is the No. 6 firing position (No. 4 and V6). The following valves can now be adjusted:
- V8 Exhaust: 2, 5, 6, 7
- V8 Intake: 3, 4, 6, 8
- V6 Exhaust: 2, 3, 4
- V6 Intake: 4, 5, 6
- Reinstall the rocker arm covers using new gaskets or sealer.
- Install the distributor cap and wire assembly.
- Adjust the carburetor idle speed, if necessary.