More than likely, what you were hearing was not. “valve tap”, but was actually, “pinging”, or, “pre-ignition”, or, “knocking”.
This could have been the result of…
using gas of too-low an octane
carbon build-up in the combustion chambers
badly-worn spark plugs
(most likely) ignition timing that was advanced too far.
Eventually, your valves would have been worn-down to something resembling pencil stubs, and your pistons would have had some serious damage done to them.
Modern cars have knock sensors that retard the ignition timing when knocking/pinging/pre-ignition is detected, and thus you are not likely to experience this problem with a modern car.
It wasn’t “valve-tapping”…