Indexing the Jeep 4.0 HO Distributor

By Dino Savva

The procedure is as follows:

1) Note the position of the terminal for the no.1 spark plug wire on the distributor cap and scribe it on the distributor body with a marker.

2) Remove the distributor cap.

3) Remove the valve cover so that the valve springs can be seen.

4) Rotate the crankshaft using a socket wrench with a 19mm socket until the notch on the crankshaft pulley lines up with the "0" mark on the timing cover (below). The valve springs on the no.1 cylinder should be relaxed and the valves closed. This will indicate that the no.1 piston is at TDC at the end of the compression stroke. If the springs are compressed, the valves are open (end of exhaust stroke) so you'll need to rotate the crank pulley another 360*.

5) Once you've verified that the no.1 piston is at TDC on the compression stroke (both valves closed), the rotor on the distributor should be pointing near (but not at) the mark for the no.1 plug wire terminal.

6) If not, remove the distributor retaining bolt from the block, pull the distributor out until it rotates freely, and rotate the distributor body until the rotor lines up with a mark made exactly 3.0cm clockwise from the edge of the cam position sensor's rubber plug (bottom). This will be just past the no.1 plug wire terminal in a clockwise direction. If you've got it right, the "ears" of the loop for the distributor retaining bolt will be either side of the threaded hole in the block. You should not need to cut the "ears" to correctly position the distributor unless you've installed an aftermarket camshaft.
Note: The distributor will rotate as the distributor gear meshes with the camshaft gear.

7) Bolt down the distributor, reinstall the valve cover, and you're done.

The notch on the crankshaft pulley should be lined up with the "0" mark on the timing cover.

When the no.1 piston is at TDC at the end of the compression stroke, the rotor should be pointing in the direction shown (five o'clock position when standing on the passenger side looking towards the driver's side).