So I have my 93' torn apart at the moment. I've got a few things that I'm doing to it, one of which is setting the valves since I have no idea when they were done last. With that said, I'm following the cummins shop manual and it says to push in the timing pin to locate TDC on cyl #1.

Okay, cool. So I'm turning the engine over and I push the pin in and it goes in about 3/8ths of an inch. I can keep turning the engine over till I'm blue in the face at this point... Am I missing something here? Shouldn't this thing click into place and lock the gears when cyl #1 is at TDC?

I'm used to sticking a pin in a Cat engine (blasphemy, I know but I work with a ton of Cat stuff) and it holds it in place, you set the 1st set of valves. Pull the pin out, rotate engine 360*, put pin back in and set the rest of the valves. Does our mighty Cummins not work that way too?

 

Be careful, you can break it off in there by rotating the engine while it is engaged. I managed to get the little plastic POS timing pin stuck, and had to rotate the engine a hair backwards from the way I had been to get it loose.

The "companion cylinder" method is what I used to set my valves:

http://dodgeram.org/tech/dsl/valve_adj/12_valve.html

You can use the nut behind the fan (1 /7/16" or 36mm) to rotate it backwards, and the barring tool to rotate it the other way.

 

you can also rotate it backwards with the 7/8 nut on the alternator

 

I spray a little brake clean at the pin then a little wd40. That makes it a little easier. Seems like they can be a bugger to drop in sometimes, then having your hand in a akward position on top of that makes it that much more fun.

 

in case you have not seen this here is a link from the stickey. Near the bottom it describes the "companion cylinder" method SeanB32 talked about.

 

If it's moving 3/8" the tip is broken off it. It should only move about 1/16" until it hits the hole.

 

If you are trying to find TDC, to set timing, this is what I do.
My hands are too big to get in there so I use a very long pair of needle nose pliers, reach down and pull the pin out.
The only thing that holds the pin in the case is an O-ring.
Next lube it up with whatever you want then shove the pin back in.
I then mark the side of the pin with a yellow marker so I can see if it has moved in far enough and, when I'm finished, that I pulled it out far enough.
I have a barring tool that goes into the plugged hole on the transmission adapter plate just next/behind the downpipe to engage the teeth of the flywheel.
I remove the # 1 valve cover and bar the engine over (crankshaft turning clockwise) until the intake valve closes.
If you mark the dampner pulley, be ready to engage the pin in approx 1/2 crankshaft turn more.

Or; if you are just trying to adjust the valves, I do this.
Remove the valve covers.
Turn the engine over with the alternator pulley.
Whenever an intake or exhaust valve is fully open, adjust the opposite valve of that cylinder. For instance; If the intake is fully or dang near fully open you know the exhaust is fully closed. Same can be said for the intake valve when the exhaust valve is fully open.
Watch and mark each rocker as you go.
I adjust them all once then turn the engine over to double check them all again.