I need a DIY replace Timing Chain/Lower Timing Chain Rail, anyone???

[Centege]

Let me begin by saying that I am very bad with forums, I've been searching for 2 days with no luck yet! I just can't seem to get anywhere, so I am asking for your help. I have a 2002 525i that I am repairing the head on, fyi: it had a broken exhaust valve, now at machine shop! Anyhow, I got everything off already for the head replacement and now I want to replace the timing chain because when I was taking off the head I broke the "Timing Chain Rail For Lower Timing Chain" the one that sticks out past the block! Or better yet if someone knows how to replace this rail. So hopefully someone nice enough can help me with this. I'm not a real expert at this so also some pictures would help as well.

Also would someone know why an exhaust valve would break, cheap gas or timing?

[JhwShark]

Post a pic of the broken valve and the associated piston top! Also, describe what the car was doing when the valve broke and any work done previous to the brake.

Get the two book Bentley manual for DIY engine work (the one book Bentley or Haynes may help)...scan some of the appropriate pages and post them...then I can help.