Distributor Removal/Installation Procedure

Written by: Mike Ervin

Tools Needed:

Distributor Wrench
Some kind of marking pen that won't rub off

You need to have a little mechanical ability to handle this task.  It is not as hard as it it might seem, but you will still need to know a little about your engine and your truck.

The procedures here will be much easier if you rotate the engine to top dead center TDC on the #1 cylinder beforehand. The easiest way to do this is to remove the #1 spark plug, (front plug on the drivers side) and stuff a tissue into the hole lightly (not ALL the way in). Rotate the engine by hand until the tissue pops out, indicating the compression stroke. Then make sure that the timing mark on the balancer is exactly lined up with "0" on the timing indicator - you will then be exactly TDC on #1.

  • With the engine at TDC on #1 cylinder, remove the distributor cap, and disconnect all wires plugged into the distributor. At this point you are going to make three marks. The first should be on the lip of the distributor (where the caps sits), and will indicate where the rotor is pointing. The other two marks will allow you to align the distributor body with the intake manifold so that you can install the distributor in exactly the same position it came out. Make one mark at the base of the distributor and make another one somewhere on the manifold close by - you will line up these two marks when you reinstall.
  • Loosen the distributor hold down bolt, and move the hold down clamp out of the way. Gently lift the distributor up. You may have to twist the body slightly to free it up, but try to lift it up as straight as possible, because there is one more mark that you should make. As the distributor gear moves past the cam gear, the rotor will rotate. Marking the position that the rotor ends up in after removal will greatly aid installation later on. Don't worry, if the thing really fought you coming out, and you couldn't make that mark, you can get by without it.
  • To reinstall, drop the distributor body down into the hole loosely, and line up the two marks for the distributor body and the intake manifold. Then spin the rotor until it points at the mark you made AFTER removal. If you weren't able to make that mark, position the rotor about 1" away from the first mark you made. Carefully lower the distributor the rest of the way in. You may have to jiggle the rotor or spin it back and forth slightly to get it to mesh with the cam gear and oil pump drive shaft.
  • Rotor is not pointing at the original mark, you should pull the distributor out and reinstall, changing the initial position slightly. If you are installing a new cam, you will almost definitely have to do this a couple of times.  Also most of the time you will have to turn the oil pump rod by hand with a long straight screwdriver to get the distributor shaft to line up and drop down all the way.  To do this use a flashlight and look down into the hole in the intake and you will see the rod with the slot in it.
  • Don't forget the hook up a timing light and a tach before you start the engine because you will need set the timing and the idle if need be.

Installing if the engine has been rotated with the distributor removed.

  • The same applies for finding TDC as in the paragraph at the top of this article.  Once you have TDC located correctly, you need to rotate the engine two revolutions.  Go one full turn and on the next turn stop at what you normally have your initial advance set at instead of going all the way to zero again.  I set mine at 13 degrees BTDC but yours may be less.  This sets the static timing and will let the engine start without much cold cranking.  Cold cranking will put excessive wear on any new parts, especially a new cam and lifters.  Now put the cap on the distributor and put a mark directly inline with the #1 tower of the cap on the distributor body.  Install the distributor and line up the rotor with the new mark you just made.  This is called static timing the engine.  This sets the initial timing exactly, so you won't have to be in a hurry to check the timing with a light after the engine is running.
  • You will more than likely need to turn the oil pump driveshaft so the distributor will drop all the way down.  As you lower the distributor into the engine, the distributor shaft will go into the oil pump shaft slot and the distributor gear and cam gear will mesh.  If the oil pump shaft doesn't match it won't let it go all the way down onto the intake.  You can use a long straight screwdriver and a flashlight to turn the shaft.  It needs to be located somewhere around the 3:00 to 9:00 position.  The easiest way I've found to to get it right is find where it will go all the way down, even if it isn't lined up with #1.  Just hold the distributor body in the correct direction and turn the rotor until it falls in place.  Then pull it out just far enough to be able to clear the cam gear.  Rotate the rotor one tooth at a time and drop it back down.  This will turn the oil pump shaft as it goes down.  Keep doing this until it lines up with the #1 tower.  This is real easy to do and saves a lot of headache guessing at the oil pump shaft location  All you after here is to move it one gear tooth at a time until the rotor lines with #1 tower.
  • As for what position the distributor should be in.  It needs to be installed as close to the original position as it was before removal.  Some people will tell you it doesn't matter where the distributor cap location is.  Well really it doesn't.  What matters is if your plug wires reach and if the vacuum canister is able to clear when you want to advance or retard the timing.  In all reality, you could use any tower on the cap as #1 as long as everything else hooks up.  Take a look at the firing order picture below for a general position the distributor cap should be.  Follow the above instructions for the rest of the install.  As in the above article, after the engine is running don't forget to check the timing and adjust if needed.  For a picture of the firing order and spark plug wire placement for a V8, click here.  For V6's here is the firing order.