Valve lash settings are critical on a racing engine. The valvetrain takes an enormous amount of punishment. Wear that occurs in this area causes clearances to increase. Monitoring valve lash setting affords you the opportunity to replace weak or failing components before they actually fail. Failed valvetrain components can result in severe and expensive engine damage. Let’s say you are at the races adjusting your valves and you find a particular valve, say #3 exhaust, is noticeably looser than any other. You set it to the correct adjustment and make a note of this on the blackboard in your trailer. The next time you adjust the valves, all the valves seem to be holding their settings well, but #3 exhaust is again noticeably loose. Check your rocker arm, pushrod and roller lifter, on #3 exhaust. There may be a weak or failing component. A failing lifter will continue to add clearances to the valve lash settings right up until when all the needle bearings in the roller fall into your oiling system. This could occur just before or after your cam is damaged. Monitoring these indicators can be a lifesaver. Components don’t generally fail all at once. They usually give warning. Please look and listen!