Need some advice PLEASE
 

I have a 98 dodge cummins 24v.
I changed to 100hp injectors and all was great for about 1600 miles. I started hearing a ticking sound louder under acceleration. Pulled valve cover to adjust valves and while in there noticed 2 injector hold downs had loosened. I retourqed them and the ticking got better but not gone. Is it possible the copper washer is damaged? The sound kinda sounds like exaust but comming from under valve cover. Truck runs great. Starts first time. No diesel in oil. I do not tow so temps never see above 1100. Any help is much appreciated.

Pull valve cover, check it while running,check the torque on all the injectors or valve adjustment?

Checking it while running would lead to a big mess and possible injury.