timing set questions

[thistle3585]

I am changing out my timing chain set. A couple questions related to this process.

1. Can I swap just chain or should I do sprockets too?
2. I can get the top sprocket off about halfway but can't get the bottom one to budge. Is there a secret to this? Do the timing marks need to be in a specific location to do this?
3. I assume I'm as well off to redo the oil pan seals, oil pump seals, water pump seals during this process. Anything else I should look at while I have it apart?
4. I broke a bolt off flush with the block. It is the upper bolt on drivers side. I figured I'd drill and retap it. I don't know how deep it is in the block and am concerned about punching through in to something else. Any feedback on this process?

 

[Torxhead]

You could try a gear puller for that bottom gear, and I would suggest changing it since the chain will put wear marks on both gears. There is a mark on each gear and they should be lined up with each other at install. There are videos on the net that show this installation. Removing a broken stud can be tricky, again check for repair videos. If just the head is broken off and the stud is not jammed to the bottom of the hole, sometimes a left handed drill bit will back out a broken stud. Otherwise if it is locked in to the bottom of the hole, it will have to be drilled out. If the thread is destroyed during this process a Heli-coil or other type of thread insert can repair the thread.