Regular maintenance of your vehicle is important to keep it running properly and to prevent expensive repairs down the road. Part of this maintenance is checking and adjusting the valve lash. The valve lash is the clearance between the tip of the valve stem and the rocker arm or cam follower.
To check the valve lash, you'll need a feeler gauge. The feeler gauge is inserted between the valve stem and the rocker arm or cam follower. If there is too much clearance, the gauge will slide in easily. If there is not enough clearance, the gauge will be difficult to insert.
To adjust the valve lash, you'll need to loosen the adjusting nut and screw on the rocker arm or cam follower. Then, you'll rotate the engine until the lobe of the cam is at its highest point. At this point, you can tighten the adjusting nut until there is the correct amount of clearance.
It's important to check and adjust the valve lash regularly to prevent engine damage. If the clearance is too small, the valves will not open fully and the engine will run poorly. If the clearance is too large, the valves will bounce and the engine will also run poorly.
If you're not comfortable checking and adjusting the valve lash yourself, you can take your vehicle to a mechanic and they can do it for you.