Complete rebuild.
Do I need a micro meter to measure the drop in the first cylinder, to find to dead center. OR is just eyeballing it close enough to line up the timing marks.

 

What are you trying to do?

 

Trying to find top dead center. One of the rebuild manuals directs to place a micro meter on top of #1 cylinder to measure Exactly when Top Dead Center occurs. Then install your timing chain and line up timing marks.

I'm thinking, eyeball #1 at TDC, align timing marks, install chain.
It would be hard to be off by much. With a stock system, there is no adjustment. The marks are aligned, or they are not. Why measure TDC to the thousandth of an inch, when just placing the piston at TDC will get you the same result.

 

If I remember correctly when I was rebuilding my 4.0 all you need to do is install your pistons, cam and timing gears/chain... Your cam and crank have groves that will only allow you to install the timing gears and chain where they need to be... Also on you timing gears there are factory marks on the face of each gear that will face out and line up and also show TDC if everything is done properly... I also believe that you have to install the chain and gears together as one because there isn't enough slack in the chain to put it on after...

You will also want to be careful when installing your distributor as you can get them a tooth or 2 off and will drive you nuts trying to figure out why it won't run.

Hope this helps.

 

I'm not positive on the jeep but on most engines the key is pointed at the top of the block. I put my hand on the piston top and find where the crank rocks back and forth without the piston moving and then center the crank.