bent 4.0 pushrod

[Cjmartz2k]

So my dad said the jeep started making a ticking noise over a couple of days, than started to hard miss and clack pretty load. He pulls the valve cover and finds the #4 cylinder exhuast pushrod is able to be "wiggled" back and forth a little (not just turned) and he said he could push it down and feel the lifter squish down without to much effort. I remember them being pretty stiff, but I'm not sure what his idea of easy is (I'm in Iraq, kinda hard to feel for myself). So he pulls the rocker arms and the OTHER (intake) pushrod is bent (not just a little)!! He said there was a mark on the side where you could see it was rubing. I'm thinking piston vs. valve, but how?? It's been running for about 10k miles since the last time I had the head off. I've got .030 shaved from the head, shims under the rocker arm bridges, mopar performance springs, and a crane 753905 cam just for reference. Can piston/valve clearance decrease on it own? What else can bend a pushrod?? Also, he had to have the distributor replaced maybe 1000 miles ago or so, because it actually bounced up out of the boss it sets in, but the shop that replaced it said the gear on the bottom didn't look chewed up or anything, so they just droped in a new one. Any ideas? Unless I hear it's a real bad idea, he's just gonna put a new pushrod in, turn it over, and see if it bend another. I was already starting to get a stroker ready, so if it breaks something else by trying that again, no biggy, but I would like not to if I can. I do want to use the head on the stroker too, so messing it up would suck. Thanks in advance!!

 

[Dr. Dyno]

Piston to valve clearance doesn't decrease on its own unless the timing chain is slack enough to skip a few teeth or it breaks altogether. A third possibility is if there's a loss of lubrication in the valve guide and the valve stays stuck open. The same thing can happen if a valve spring breaks or gets bound. You don't have enough valve lift to reach spring bind so the last scenario is pretty unlikely.
You might wanna check the intake manifold vacuum and do a compression check. These might give clues to whether you have any bent valves.