tapping noise at 2000 revs

hi again
i have a 89 1.8 auto clipper which i have just changed the carb and has sorted most of problems out but now i have a new problem….
when the car is in drive and the rev's go over 2000k it has this tapping noise which sounds like the tappet's but i thought when the tappets need ajusting you can here them all the time..  
just wondering if anyone else has had this problem?
or i anyone knows what up with my car?
it seems to run ok i travel 80 miles a day to work and i have had no problem yet i'm just worried i'll cause a bigger problem later.
many thanks

daisy  :dontknow: