I have a 390 in a Mustang and after changing the lifters(anti-pump up),pushrods and rockers (adjustable Crane) I still have tappet noise at 1500RPM.There is no noise at any other RPM just 1500RPM. The motor was rebuilt last year (done 2000Km`s)and the noise has been there since the rebuild at 1500RPM.The new motor included a new cam and intake manifold, the heads were also re done with new springs and valves/seats. We adjusted the rockers down 30 thou after intiall contact using dial gauge.
Has anyone had this problem before?
Cheers

it seems unlikely to me that lifter noise would perpetuate itself at 1500 rpm only. it soulds like a imbalance issue somewhere

Anti-pump up lifters have a distinct clicking noise at low RPM due to the nature of the valve body design, however this was more prominent with Rhoads lifters. I'm not familiar with Crane's product but my understanding is they should not click.