The valve adjustment procedure described in this page was performed on a cold engine. The valve clearance on a hot engine is different than a cold engine.
Disconnect the negative battery cable, unplug the PCV valve as shown in the picture.
Unbolt the bracket located on top of the valve cover gasket without disconnecting any of the vaccum hoses and flip it over the intake plenum.
Remove the four nuts and washers that secure the valve cover in place.
Remove the four grommets, lift on the valve cover and remove it from the engine.
There are a few ways to adjust the valves, one is to set the number 1 cylinder in compression stroke and adjust both intake and exhaust valves at the same time considering that both valves are in their closed position, moving to number 2 cylinder, followe by 3 and 4.
Another way is to adjust all the intake valves followed by adjusting all the exhaust valves.
The way we did it as you can see in the picture, we made sure that the opposite valve was open ( Intake valve shown in the picture) to be sure that the valve we are adjusting ( exhaust in picture) is completely closed; after we adjusted the exhaust valve, we rotated the engine untill the exhaust valve was in the open position to adjust the intake valve, we did this to all 4 cylinders.
To adjust each valve, loosen the nut, adjust the lash with a flat screwdriver as shown in the picture with the correct gauge inserted between the valve and the rocker arm, once the correct lash is set, tighten the nut .
Toyota recommends to adjust the Intake valves to 0.010" of an inch, and exhaust valves to
0.012" of an inch with a cold engine.
Remove the old valve cover gasket and install a new gasket.
Replaced the front and rear valve cover seals with the new ones provided with the valve cover gasket, apply a small coat of silicone to the edges of the seals to make sure that there will be no oil leaks.
Install the valve cover, install the new rubber grommets, install the remaining components in the reverse order you took them off, make sure that all nuts and bolts are properly tightened, connect the negative battery cable back on and start the engine, if you did everything correctly the truck should run smoothly, you may be able to hear the valvetrain when the engine is cold, but as the engine warms up the sound should dissapear.