Written by: Mike Ervin
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
- 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
- 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.