How do you calculate valve lash?

To determine the valve lash, subtract the squish from the desired valve opening lift. The cam in the graph is for a flathead, using squish of 0.002″ the valve lash should be 0.0127″ or 0.013″. The exhaust could be set a couple thousandths larger to allow for thermal expansion.

Do you set valve lash hot or cold?

The easiest way to do this is to warm the engine up (getting the oil temp up to around 200 degrees Fahrenheit should do it), lash one intake and exhaust valve properly, allow it to cool and check to see how much the lash has changed.

When should valve lash be set?

Set the intake valve lash when the exhaust valve is beginning to open. This will put the intake lifter at the base circle which is where you want it to be. Then set the exhaust valve lash when the intake valve is about halfway down on the closing side. Be Consistent.

What will improper valve lash cause?

Too much or too little valve clearance can result in poor performance or a rough idle because the engine can’t “breathe” normally and operate at peak efficiency. Too much clearance means the valves will likely clatter and, over the long term, cause damage to the valves, camshaft lobes or rocker arms.

Do valves get tighter when hot?

Valves are tighter (less clearance) when hot. Valve stem is pretty long, and even though the head grows slightly, the stem grows the most given it has so much ‘meat’ from valve face to stem tip.

How do you set lash on hydraulic lifters?

To adjust hydraulic lifters two fingers spin the pushrod as the lock nut is gently tightened. When resistance is felt on the pushrod, that’s zero lash. The adjuster is tightened to specs then the setscrew locks it in place. When changing valvetrain components always check rocker arm geometry.

How do you adjust engine valve clearances?

Use a ring spanner to loosen the locknut and turn the screw clockwise to decrease the gap, and the opposite way to increase it. When the clearance is correct, hold the screw with a screwdriver while you tighten the locknut, then re-check the clearance.