escort 98

hiya! dno if u can help but my brother got a 98 escort 1.3 endura-e, he had a running problem so we done his tappets, as ther were reli noisy, we found that 2 ov ther were about 3-4 mil out, afta we corrected the tappets we drove the car and 2 days later they were the same, so we done them agen, this time within a few miles the same agen the 2 tappets keep coming reli far apart we are running out ov thread on the rocker so we just dnt no, any halp is greatly appreciated! thanks alot!!
dean