6nz heavy ticking

I know nobody wants to read a novel, so I'll shorten this as much as possible. I have a 6nz cat. Just did a platinum rebuild on it. I noticed it had kind of a real heavy ticking noise. I thought i remembered hearing it before the rebuild, just figured it was a little louder now that everything was new and tight. Got about 10k miles on it before it broke 3 out of 4 rocker shaft bolts on the front assembly. Also wiped out the #2 injector. I got the upgraded bolts (thanks for the heads up, Mr. Haney) and another injector. Put it back together, my mechanic says he hears the realing loud ticking, says it sounds really ugly, likens it to a cylinder scuffing, but knows that isn't it. I go about 1700 miles before it broke again, this time snapped the #2 injector hold down bolt (that's what I get for re-using it. I know, I'm an idiot.) Ripped every o-ring off of the injector and dumped 12 gallons of fuel into the crankcase. Drained it all, replaced oil and filter, put new bolts on all the injectors and put another new injector in the #2 hole just in case the other one got damaged. Ran the overheads again. Fired it up, ran better than it ever had. Sounded great. The heavy "ticking" was all but completely gone. I basically thought it was just regular valve noise. Now the problem: the truck has hard starts (never an issue before) and the noise is coming back. What in the world is going on?

 

Not a bad idea, but how would I run that down and why would it have hard starts all of a sudden?

 

Ouch! My cam is brand new, but I think we figured out the issue today. Bushings inside the rocker arms have side play in them. Going to get them all refurbished and keep my fingers crossed.