Wiped cam/lifter?

Ouch, sorry to hear that John, but..i'm an idiot, I forgot to reconnect the carb to rocker cover hose.
Having reconnected the hose from the breather to the carb, my smooth running/tickover was restored.
BUT quick 15 min drive and the tappety sound comes back and stays.....until i get the car in the garage and stops, presumably, ready to come back later
Oil is 15/40, havent changed it for a while (3,000miles)because its still clean.