Loosen and back off the adjusting nuts on the intake and exhaust rockers. Place a .004" feeler gauge between the cam lobe and rocker arm. Snug down the adjusting screws (with your fingers) until each screw just touches the valve tip, then move the feeler gauge back and forth to make sure there is drag (not tight/not loose) and tighten the nuts with a wrench. Now recheck the clearance at the valve with a .006" feeler gauge. The feel should be a snug .006" or a loose .005". Re-adjust the screw if you dont get this feel on all four valves. Use same procedure on remaining three cylinders. There is a 1.5 to 1 rocker arm ratio, so .004" at the cam gives you a snug .006" at the valve. This procedure reduces the risk of uneven rocker adjustment. Once you get the feel of a snug .006" clearance, you will find you have proper setting for long cam life and minimal (if any) clatter.
IMPORTANT: I always torque the adjusting nuts to 15 ft.lbs. Tighten
the nuts with a wrench enough so they wont come loose, then rotate engine
until rocker arm depresses valve about half way. This will allow
room for the torque wrench and the pressure against the adjusting screw
will keep it from turning while you are torqueing.