Yes you can, as long as you did not bother the other ones. Just adjust the one you replaced.
replace the hydraulic tappets in the rocker arms, valves are non adjustable.
Collapsed hydraulic valve lifter? Rocker arm (valves) need adjusting?
Adjusting the valves on a Caterpillar C 15 Engine is easy and does not take long at all. All you need is a wrench and a feeler gauge, You will then loosen up the bolt, place the feeler gauge in between the rocker arm and valve and then turn the wrench until the rocker arm touches the feeler gauge.
Everyone I know says 25 foot pounds but you really need to go online because you are adjusting the valves and there is a specific order for doing it.
To set the valves on a 50cc Jackel wheeler, start by removing the valve cover to access the valves. Use a feeler gauge to check the clearance between the rocker arms and the valve stems, typically aiming for the manufacturer's specified gap (often around 0.002-0.004 inches). If adjustments are needed, loosen the locknut on the rocker arm and turn the adjusting screw until the correct clearance is achieved, then re-tighten the locknut. Finally, replace the valve cover and ensure everything is secure before starting the engine.
Either that or remove the rocker arms and do a cylinder leakage test.
Bring the piston up on tdc right after the intake valve closes and then loosten the adjusting nut until there is slack in the rocker arm. Tighten it down until the slack is gone,{you can tell by turning the push rod} then turn it 3/4 more. Do this on all cyls.
take off the valve covers, and the rocker arms will have adjusting nuts on them, tighten them to zero lash and the back off 1/4 turn.
You can adjust tapping valves by adjusting the lifters.
To adjust the valves on a 1992 Mitsubishi Eclipse, first, ensure the engine is cold and remove the valve cover to access the rocker arms. Use a feeler gauge to measure the clearance between the rocker arm and the valve stem, adjusting the screws on the rocker arms to achieve the specified clearance, typically around 0.008 inches for intake and 0.010 inches for exhaust valves. After adjustments, recheck the clearances to ensure they are within specifications, then reassemble the valve cover. Always consult the vehicle's service manual for specific torque settings and procedures.
The best way to tell if the valves are closed is to observe the rocker arms. When they are both at the top of their travel, valves are closed. Feel the rocker arms and try to move them, if they move their at the top of their travel.
They are not adjustable.