hey guys i am helping my son adjust his valve in his 65 mustang 289 eng we had it rebuild in jan this year and the other day we started to hear a pecking so we try to adjust it and evertime we tighten it down it would go away then come back so we thought we had a bad lifter ( hyd ) and we changed it and now we have another doing the same thing so do you think we are have a bad run on lifters or what i have cut a set of old valve cover off so we can adjust them running i have back them off and little til they peck and tighten them dowm till they stop is that the right way ?

i need help please