How are valve lash measured?
Valve lash is measured with a feeler gauge between the tappet adjusting screw and the end of the valve stem. A feeler gauge measurement is either a go or no-go. To adjust valve lash, loosen the locknut (10mm), and turn the tappet adjusting screw until the drag on the feeler gauge is correct.
What causes excessive valve lash?
Burnt exhaust valve(s) Broken valve train components (springs, pushrods, lifters, camshaft) Limited or reduced lifespan of valvetrain components. Excessive valve guide and valve seat wear.
What can incorrect 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.
Is valve lash the same as valve clearance?
Valve Lash or Valve Clearance is the gap between the Rocker Arms and the valve tappet. This clearance must be tightly controlled. If it is too little, the valves may not seat properly. If you have too much valve lash, you eliminate the more “gentle” sections and are basically “slamming” the valve open and closed.
How often does valve lash need to be adjusted?
Valve lash should be checked and adjusted as needed as a normal maintenance process every 1,000 to 3,000 hours after the initial adjustment.
Should valve lash be set 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.
What should the valve clearance?
Opinions may vary between piston and valve manufacturers, but a popular consensus is a minimum clearance of . 080-inch for the intake and . 100-inch for the exhaust. The exhaust valve expands more due to heat from combustion, and therefore needs additional clearance.