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1995 Blazer 4x4, Re-Install Distributor, Help to set timing pls. TDC, BTDC

08-13-2007, 04:09 AM
I had to remove the distributor on my 1995 4x4 Jimmy. I had marked everything to make re-installing easier, but accidently cranked the starter before the distributor was back in.

I need some help with getting the timing set.
We found the timing mark on the front driver's side of the timing cover. It looks like a notch or "Vee" cutout. This is the mark that doesn't move.

Looking at the harmonic balancer, I find it has two grooves across it. I was only expecting one mark on the balancer that would be TDC. Moving around the harmonic balancer, one mark is about 90 degrees after the other. On the rearward edge of the harmonic balancer there is a little bump. Some friends look at this bump and say it looks like a mark also. Maybe it has a white line through the middle of it. The bump is located at least 120 degrees rotation from either of the two grooves across the harmonic balancer.

QUESTION: Do I use the first groove, or the second groove to line up with the TDC mark on the timing cover? What is the reason for the second groove?

The Hayes Manual says when the distributor is fully seated, "the rotor button should point within a few degrees of the "6" stamped on the bottom of the distributor body.

The rotor won't line up exactly on the "6". Depending on how I engage the bevel cut gear, I can put the rotor pointer either "before", or "after" the stamped number "6".

QUESTION: Is it better to put the rotor pointer "Before", or "After", the stamped "6"? Consider the normal CW rotation of the rotor.

QUESTION: In another post, I read something about the arrow on the distributor shaft housing. This is a long arrow that points skyward. How do I use the arrow?

Thanks for any help and suggestions.


Everything below is info. that might be helpful to someone else trying to solve similar problems.

1. Take a marker and draw a line across the top of the rotor that corresponds to the slot on the bottom of distributor shaft.

2. If you need to use a screw driver to turn the oil pump shaft, make a mark on the top of the screw driver to match the slot on the end of the screw driver.

3. Use a small mirror to look down into the engine, and see the slot in the oil pump shaft. ***Everything will be reversed in the mirror*** If you see the slot as "7 to 1" o'clock, in reality, it is "5 to 11" o'clock. Go practice in your bathroom mirror. Lay a pencil flat on the counter and look at it in the mirror.

4. Plan on dropping the oil pan or maybe pulling the engine if you drop your screwdriver into the engine. Ask me how my cousin learned this! We call him butter fingers.

If you consider that the rotor turns "clockwise", I can also see a circle stamped in the bottom, "just before" the "6". The circle seems to line up with the position of the "Number one" terminal under the cap. (This is the side terminal cap, so the No. one spark plug boot is nearly opposite the terminal. If you look at the bottom of the cap, you can "trace" the route from the terminal to the boot connection. )

Here are very helpful post if you are dealing with hard starting:

08-13-2007, 08:39 AM
What engine code and what engine?
Flat top dist or old style?
The two timing marks can be confusing.

First you need to find TDC compression stroke.
Do not worry about the oil pump shaft it will take care of itself.
Getting the dist dropped in on TDC compression with the rotor pointing to no one cylinder plug wire is what you need to figure out.

Pull valve covers so you can see valves working.
Get a socket and ratchet or breaker bar on crankshaft damper bolt.
Rotate engine until you see no 4 cylinder valves rock.
One closing and one opening.
Stop right there. You will be on no 1 cyl TDC compression.
The right timing cover mark should be lined up with the crank pulley mark.

That is where you need to set the dist in and point the rotor to no one cylinder plug wire terminal.

But we need to know what dist you have.
Is it the old style dist or the newer flat top dist.
What is the engine code?

08-14-2007, 03:47 AM
Do not worry about the oil pump shaft it will take care of itself.

Dear MT, Thanks for the quick reply.

My engine is the 6 cylinder with the flat style distributor cap.
In your response you say "oil pump shaft will take care of itself."
If I don't get the slots to mesh, then I can't tighten down the distributor hold-down bolt.

Is it okay to rotate the crank with the ignition off, so that the oil pump shaft will "fall into place"?
Next I would tighten the distributor hold down bolt.

Update... We got the engine running. The correct groove/mark on the harmonic balancer is the first one that passes the notch on the right side timing cover below water pump. The second mark is 90 degrees rotation after the first one. Don't know what it is for, other than to cause DIYer confusion. The trucks battery is a bit weak, but it starts fine when we jump from another car.

Things I learned....... Hints and Tips...

1. Remove the hood from the truck when working on the distributor. There is a bolt on each side of the hood that can be removed while the hood is closed. (Use a sharp tool to scribe a line on both halves of the bracket. Makes it easy to set hood in proper position during re-assembly.) Takes a person on each side of car to easily remove the hood.

2. There is a wrench made for the purpose of reaching the distributor hold down bolt. It is shaped like an "L". Your rachet plugs into the top of the 'L'.

3. As you lower the distributor into place, the rotor will turn clockwise about 30 degrees. We want the rotor to end up pointing at the stamped "6" (in base plate), so position the rotor 30 degrees CCW from the "6". I think if you point the rotor at the frontside cap hold down screw before inserting, that it will rotate into proper position (no. 1 plug TERMINAL ) Find the number one plug terminal on the underside of distributor cap. If you have the flat style cap with side terminals, you will learn that the Number One plug wire boot is located approx. 180 degrees rotation from the number one terminal on underside.

4. When trying to get the gears to mesh into proper position, don't get hung up on wheither or not distributor body is sitting on the little pin that keeps it from rotating. Concentrate on getting the rotor into the proper orientation. Once you find the correct groove, you can then raise the distributor slightly to get the body on top of the index pin that sticks up out of engine block. You are able to swing body in either direction, without gears coming apart.

5. If you off from the groove you want by +/- one tooth, it is easy to jump one tooth left or right. Don't pull distributor out, rather torque the rotor with your hand as you gently lift the distributor until gears just clear each other. You can feel when gears break apart. Once gears are clear, rotate the rotor a little bit in the desired direction. Let the weight of distributor fall as you continue turning, gears will fall into the next groove.

6. Forget what I said earlier about using the mirror and screw driver to get the slot in oil pump shaft into correct position. Once I found a spot where I could get the distributor to drop down flush I knew the slots were aligned. At this point, I torque rotor while lifting distributor until gears just break free. Lift no higher. In this position, gears have broken free, but shaft slots are still coupled. Rotate rotor to the desired angle, slot is now in that position. Next, you worry about getting the gears to mesh. Keep trying, you'll get the hang of it.

7. Don't strain your back leaning over the fender. Put some cushions on it and lay your chest/stomach/groin (depending on your height) on fender.

8. I was very tempted to get rid of that pin on the engine block that keeps the distributor body from rotating. Without that pin, one could loosen hold down bolt and rotate distributor body into a positioin that makes it easier to get at the front screw that holds down the cap.

08-14-2007, 08:55 AM
You are welcome and thanks for posting back how it went.
Sounds like you are getting the hang of it.:grinyes:

Yes if the oil pump shaft does not slip in the bottom of dist just turn the engine to where it drops in.
Just takes a little practice.

The other mark is for a different crank pulley or engine set up.
Very confusing.
That is why I told you to pull valve covers to check where the right mark was.
Also that is a good way to check true camshaft timing.
Good Luck

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