bga and the tapping noise

[Ian.B]

Several weeks ago there was a discussion around tapping noise from the engine which increased with revs and was uniformed in its intervals..bga stated it was tappet/stroke
cam..could clarity be given as to what it was exactly..was it the tappet or the cam causing the noise as I viewed a car today for purchase and it made the same sort of consistent knocking sound..as the revs built up and the car thundered down the road at speed the sound went..probably loist in the V8 growl but more audible at tick over and slow moving away..sounds like same sort of prob..I told the guy to get it looked at right away.