I have a 97 F150 4.6 L that I never had problems with. It started to tick at 2000 to 3000 RPM but only when it is held steady. It comes from the center of the motor. It has new re-built heads with new timing chain guides. but it is still there.

 

Were the rocker arms and lash adjusters replaced with the heads?

 

Yes the heads were sent out for rebuild and all new parts put on

 

Rocker arms and lash adjusters are new