indexing the dist?

89' xj, re-manned 4.0 block out of a 94, renix head. I finally got this mother stuffed in the bay, plumbed and wired. All is going well until I try to start it. It turns, I smell gas but after about 10 minutes of crank I'm running low on battery and wondering if I indexed the distributor correctly.

As far as I knew, when fitting the distributor down into the oil pump you should align it so that the rotor sits between the 1 and 5 wires. Am I wrong?

I'm anxious as hell to get my jeep going! The poor thing has sat with it's guts in a pile for a long time and I'm almost at the finish line! Any help would be greatly appreciated.

Bob

just a side note...I'm doing all of this on my own, so I cant tell if I'm even getting spark...maybe I should wait (GOD NO!!!) until I can have a buddy help me?

You need to find top dead center first, and then install the distributor.

I hear ya...but how do I find tdc on a long block? Do I pull the plugs, turn it by hand wait and wait for compression? I've built one engine before this, and I had alot of help from an old mechanic...did I miss a very important step here?

pull valve cover and plugs, as long as all your rocker arms are torqued correctly, tdc will be when the piston is up and you can turn the pushrods with your fingers (both valves closed and no spring pressure)

8Mud said:

http://www.angelfire.com/my/fan/dist_index.html

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Excellent link for this procedure. Just an old trick that has worked in the past for me is to check the position of the piston by using an old brazing rod through the spark plug hole to feel that the piston is indeed at TDC.
DISCLAIMER never had to do that on a 4.0.

mikeforte said:

Excellent link for this procedure. Just an old trick that has worked in the past for me is to check the position of the piston by using an old brazing rod through the spark plug hole to feel that the piston is indeed at TDC.
DISCLAIMER never had to do that on a 4.0.

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I've done it in a 4.0 I put a slight bow in the rod and make sure the last movement is clockwise while facing the front of the motor to take the slack out of the timing chain. I repeat it a few times and do it mostly by feel. I actually checked my results once with a dial gage on the rocker and was within 0.010 or so of TDC, good enough.

I also shake the rockers (side to side) a little to feel the play instead of turning the push rod. On a new motor that has never been properly oiled the lifters may not be oiled and as tight as they could be. Sometimes the push rods turn rather easily on a fresh unused motor.

I most always use a compression gage to check for TDC, you can pump the pressure up enough turning it by hand to see when you are close to TDC. A point in the exhaust stroke may generate a minimum amount of pressure, but very little compared to the compression stroke.

Sometime this summer I'm going to freshen up an extra 4.0 I have and will do some pictures of TDC, indexing the distributor and degreeing the cam. It is fairly easy to do and my mechanical (and photography) skills are some better than my language skills. Unless somebody beats me to it, we should have a sticky or a pictorial, how to, posted to the site someplace. One of those procedures that seems to generate a lot of posts.

Thanks fella's, excellent link 8mud...maybe she'll come to life today!

that has to be on comnpression stroke. the piston comes to TDC and will be lined up on your timing marks on the power stroke as well. Your valves will bothe be closed as wwell i believe. I am having this same problem and that is where I went wrong the first time. Now the damn thing runs real rough. Not sure where to go yet, but I am still searching

bigjeepman said:

that has to be on compression stroke. the piston comes to TDC and will be lined up on your timing marks on the power stroke as well. Your valves will bothe be closed as wwell i believe. I am having this same problem and that is where I went wrong the first time. Now the damn thing runs real rough. Not sure where to go yet, but I am still searching

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A stroke *cycle* is when the piston either moves from the bottom to the top or from the top to the bottom.
1. Compression, it moves from the bottom to the top, both valves have to close.
2. Power, fuel air ignites forcing the piston downwards, both valves closed.
3. Exhaust from the bottom to the top with the exhaust valve open.
4. Intake from the top to the bottom with the intake valve open.

It compresses on "1" up stroke, is pushed down on "2" the power stroke, pushes (pumps) the exhaust out on "3" the next upstroke and sucks fuel/air on "4" the next down stroke. 4 strokes.
Four cycles, two up strokes, two down strokes. In some diagrams the strokes are numbered differently.
The confusion starts when the valve action overlaps the top or bottom part of a stroke. The valves open using and oval cam, so the moment of open and closed isn't exact. But is designed to be functional rather than theoretically exact, they use what works and in some strokes the valves open earlier than you'd think.
But at the top (end) of the compression stroke at the beginning of the power stroke they are most always closed (both), for a good long while and both valve springs are completely relaxed at the same time.
Where the confusion comes in is momentarily there may be little valve overlap (exhaust closing and intake opening) where the motor can build a tiny bit of pressure. Enough to move the needle on a compression gage, but not really enough to register any, if much PSI.