Valve Lash Adjustment
Hydraulic Valve Lifters
Adjust rocker arm nuts to eliminate lash. This must be done when lifter is on base of circle of cam.
Remove distributor cap and crank engine until distributor rotor points to number 1 cylinder terminal with points open.
Note the preload and setting instructions are for factory hydraulic lifters and camshaft. Aftermarket manufacturers may have different lash suggestions/requirements. Initial setting of lifters at #1 & #6 firing positions may still be followed.
Chevrolet 6-cyl engine
Number 1 firing position:
Intake numbers 1, 2, & 4 as well as exhaust numbers 1, 3, &
5.
Turn adjusting nut until all lash is removed. When all play has been removed, turn adjusting nut one more turn. This will place the lifter plunger in the center of its travel. When above valves have been adjusted, rotate crankshaft until cylinder #6 is in firing position.
Number 6 firing position:
Intake numbers 3, 5, & 6 as well as exhaust numbers 2, 4, &
6.
Repeat adjustment.
Chevrolet V-8 engine
Number 1 firing position:
Intake numbers 1, 2, 5, & 7 as well as exhaust numbers 1, 3, 4, &
8.
Turn adjusting nut until all lash is removed. When all play has been removed, turn adjusting nut one more turn. This will place the lifter plunger in the center of its travel. When above valves have been adjusted, rotate crankshaft until cylinder #6 is in firing position.
Number 6 firing position:
Intake numbers 3, 4, 6, & 8 as well as exhaust numbers 2, 5, 6, &
7.
Repeat adjustment.
Engine Running
Readjust the lifters with the engine running and warmed up.
1. Remove rocker arm covers and gaskets.
2. Place oil deflector clips on rocker arms.
3. With engine running at idle, back off rocker arm nut until it starts to clatter.
4. Turn nut down until clatter stops; this is zero lash.
5. Tighten nut down one-quarter turn. Pause ten seconds. Repeat additional quarter turns and ten second pauses until nut has been tightened down one full turn from the zero lash position.
6. Repeat steps 3, 4, and 5 for all rocker arms.
Mechanical Valve Lifters
Mechanical lifters can initially be set much like hydraulic lifters with the difference being the initial valve lash required by the camshaft manufacturer. Hydraulic lifters are set to zero lash plus one turn where mechanical lifters are set with a feeler gauge to the camshaft's recommended clearance.
Number 1 firing position:
Intake numbers 2 & 7 and Exhaust numbers 4 & 8.
Turn crankshaft one-half revolution clockwise:
Intake numbers 1 & 8 and Exhaust numbers 3 & 6.
Turn crankshaft one-half revolution clockwise to number 6 firing
position:
Intake numbers 3 & 4 and Exhaust numbers 5 & 7.
Turn crankshaft one-half revolution clockwise:
Intake numbers 5 & 6 and Exhaust numbers 1 & 2.
Warm the engine to normal operating temperature and reset all clearances with engine running as shown above for hydraulic lifters with the exception, of course, to reset mechanical valve lash to camshaft manufacturer's specifications.
