V8 WITH MECHANICAL LIFTERS
Except BOSS 429
See Figure 1
- Run the engine until it is at full operating temperature.
- Stop the engine. Remove the rocker covers.
- Check the Valve Clearance Specifications chart for the proper clearance for your engine.
- Start the engine. Insert a step type feeler gauge (go and no-go) of the specified thickness between the rocker arm and the top of the valve. Adjustment is accomplished by loosening the jam nut (or locking nut)-the top nut on the rocker arm stud-and moving the adjusting nut (the lower nut) up or down as needed. When the proper adjustment has been attained, tighten the jam nut against the adjusting nut while holding the adjusting nut in position with a separate wrench. Check the clearance to make sure that the tightening of the jam nut against the adjusting nut did not alter the proper adjustment of the valve clearance.
- When all valves have been adjusted in this manner, stop the engine and reinstall the rocker covers.
The valve lash on this engine should be adjusted only when the engine is cold. Refer if necessary to the firing order diagram found earlier in this guide.
- Remove the valve rocker arm covers.
- Rotate the crankshaft damper until the No. 1 piston is at TDC at the end of the compression stroke. This position can be determined by observing the distributor rotor. When it is at the No. 1 firing position with the breaker points just starting to open, the engine is in the proper position for the adjustment of the valves in the No. 1 cylinder.
- On the No. 1 intake and exhaust valves only, torque the rocker shaft to cylinder head retaining nuts to 12-15 ft. lbs.
- Adjust the clearance between the rocker arm and the top of the valves on the No. 1 cylinder only, using a feeler gauge of the specified thickness. Adjustment is made by loosening the locking nut, turning the adjusting screw to obtain the desired clearance, and tightening the locking nut while holding the adjusting screw in position with the screwdriver. Check the clearance to make sure that it was not altered during the tightening of the adjusting nut.
- Rotate the crankshaft 90º in order to position the No. 5 piston at TDC, checking the position of the distributor rotor as in the adjustment of the valves for no. 1 cylinder. Repeat steps three and four.
- Follow this procedure throughout the entire firing order (1-5-4-2-6-3-7-8), until all valves have been adjusted.
- Install the valve rocker arm covers.