Valve Adjustment

Valve Adjustment

Adjusting the valve on a race engine is one the most over looked Tuning aspects out there. An experienced tuner can spot changes in their engine if valve adjusting/checking is performed on a regular basis. A valve lash that changes on a regular basis can mean a camshaft is going bad, lifters that may be failing, retainers or locks that may be getting ready to let go. Checking or adjusting the valves of a race engine should be done between every run if possible or at least after qualifying and before eliminations.

An experienced Tuner can change certain aspects of the engines performance by changing valve lash. When you tighten the gap or lash, the camshaft becomes a little bigger. This also changes the time in the engine cycle the valve starts to open and when it closes. Tuners must be very careful when changing the recommended lash when adjusting valves. The engine must have adequate valve to piston clearance, valve springs must not coil bind, if valve seals are used clearance between retainer and seal must be adequate. We always recommend that you follow the recommended lash given on a cam card to start with on your engine. As a tuner starts to work with an engine on the dyno, small valve lash adjustments can be made. A couple of thousands can be a big change on some cams.

When adjusting the valves you need to be able to “bump” the engine over or be able to turn the engine over by hand. Turn engine over in Normal direction. You can do 1 side of the engine at a time. Locate the Intake and exhaust valve on a cylinder. While watching the EXHAUST Valve turn the engine over until you see the EXHAUST VALVE start to open. At this time check/adjust the INTAKE valve for that cylinder. After you adjust the intake valve, turn the engine over again. Watch the INTAKE valve you just adjusted. You will watch this valve open all the way and then right before it closes, stop turning the engine and adjust the EXHAUST valve for that cylinder. We know this sounds confusing, but take your time and the steps are pretty simple. We always recommend adjusting the valve while engine is at normal operating temperature.

Adjusting the valves is all about feel. You will need to develop a feel for the gauge as you adjust the valves. Consistency is the key. Take your time at first and go back and re-check as many times as needed.

This is the perfect time for you to double-check other vale train components. Spin the pushrod of the valve you are adjusting, make sure it spins free and is not bent. Take a close look at the valve spring of the valve you are adjusting. Make sure the spring is not broke; you may need a flashlight to see the inner springs. Take a careful look at the locks and retainers; make sure the locks are not pulling out.