1) Get the engine to TDC. remove the distributor cap.
2) There is a screw that holds the rotor in place... remove it and take off the rotor and the plastic shield.( the screw sometimes is tight use a little valve grinding compound on the tip of the screwdriver for extra bite)
3) What you should see is 1 of the pickups the coil and the ignighter. remove the 2 screws that hold the coil in and remove the coilpack (be carfull the wiring tends to be britle)
4) now is a good time to look for oil if there is any replace the distributer oil seal he can get these online for aroud 10 bucks plus shipping.( If you see oil goto Seal replacment at the bottom of the page)
Ok you found oil inside the distributor. Its not a big deal it just takes some time to fix and fix it you must oil vapor inside the distributor is bad and it will ruin the new cap really fast.You will need the distributor oil seal, distributor O ring, silicone sealent, cleaner to clean out the oil residue,a Sharpy pen, a small rubber ended mallet, screw drivers, a small pick, and a clean area to work.
1) With a sharpy pen make a line from the top bolt of the distributor aross to the head this will help you keep the timing right when you reinstall the distributor
2) Disconect the 2 ditributor plugs and remove the 3 bolts holding it to the head 12mm I think
3) Set the distributor on a clean work surface and look at the end that came out of the head. You will see a cam key with a clip around the grove. Again with your sharpy make a line on one side of the cam key and onto the distributor shaft (just not all the way across) This will let you reinstall the came key in the correct direction. that finger on the top of it will only let you put the distributor in one way so as long as it is on the shaft the same way there is no way to put the distributor in 180' out.
4) Remove the clip form the cam key and push out the pin the cam key should now slide off the shaft.
5) Turn the distributor over remove the cap, rotor , and oil sield if you have not. You should see the pick up and the ignitor wiring and the plate that it is attached to.There are 3 screws around the outside of the plate remove them and any wirring that comes from under that plate.(again be careful not to damage any of it.
6) Using a rubber mallet tap on the shaft where you took off the cam key this will pop the shaft and bearing plate assy out of the distributor.
7) Look in the bottom of the distributor housing at the you will see the seal. Carefully remove it and install the new one with something that is non magnetic
8) Reassemble the distributor Don't panic if some of the insulation came off the wiring when you were working on it this is where the silicone comes into play. With a small pick carefully move the wiring around until it is not touching and seal it with the silicone. Don't forget to plug all the wiring back in and line up your marks on the cam key, reinstall the pin and the c clip that holds it in place. Change the rubber O ring behind the cam key.
9) You are now Ready to reinstall the distributer into the car. This is where all of your marks you made come into play Don't forget to cange the distributor O ring before you reinstall it. Remember the cam key will only let you intall the distributor one way rotate the shaft until the key way lines up and the distributor slides in nice and easy Reinstall the bolts and tighten them down after you line up the timing mark you made on the head with the one on the distributor.
Plug everything back in and start the car. If you did everything right the car should start right up.
10) If it will not start you might have put the cam key on the wrong way remember the mark you made on the shaft and the cam key did you line them back up when you put things back together? Did you plug in all the wiring inside the distributor?
I hope this helps you out and everything went well