Valve adjustment needs to be a "preventive maintenance" procedure, done at least once a year unless you've got a trailer queen that never sees much driving time. We used to include a valve adjustment as part of the semi-annual tuneup on the daily drivers 50 years ago, along with replacing points, condenser, and spark plugs and adjusting the carburetor. Electronic ignition, hydraulic lifters, and fuel injection have pretty much eliminated tuneups before the 50,000 mile mark or so. The oldtimers still need some TLC, however!
Jerry
