how to replace distributor? -

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post #1 of 5 Old 05-24-2009, 07:04 PM Thread Starter
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1982 CJ5 
Join Date: Apr 2009
Location: Silverdale, WA
Posts: 64
how to replace distributor?

never done it, need advice

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post #2 of 5 Old 05-24-2009, 11:25 PM
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1977 CJ7 
Join Date: Apr 2008
Location: Southern Oregon Coast
Posts: 42
if it still in, just mark on the engine where the rotor is pointing. when you go to replace/reinstall it turn the gear back just a hair (halfway between where it was and previous cylinder) so that the helical cut gear will be right when it slips in.

If the distributor is out you need to bring the #1 cylinder to TDC and figure out where #1 should be on the distributor.

also, if you are fighting with an AMC ign box set-up, stop wasting your time and buy an HEI ign.
scorpion26 is offline  
post #3 of 5 Old 05-25-2009, 08:47 AM
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1973 CJ5 
Join Date: Aug 2007
Location: South West Indiana
Posts: 11,180
Setting a distributor is failry easy... *IF* you are very familar with the mechanics of the engine...

If not, it can be a PITA to do.

And REMEMBER, you are working with a 27 year old engine, so some things you would otherwise rely on might not be 'Correct' anymore...

The biggest of which is the harmonic balancer where you look for your timing 'Hash' mark...
The balancer is made up of a center hub, and rubber vibration damping material, and an outer ring (with the mark on it).
AMC engines have a nasty way of vibrating the outer ring loose, so it won't read correctly anymore,
So I tell people to VERIFY the balancer as the install the distributor.

To that end, here are some instructions,

1. Disable the ignition by pulling the coil connector off the coil.

2. Find the #1 spark plug wire, and mark the location of the #1 spark plug terminal on your distributor base/body.
This is so you can tell where #1 is located when the distributor cap is off.

Marking Location Of #1 Spark Plug Terminal on CAP, then transferring it to the distributor base on I-6 engine.

3. Rotate the engine over until the ROTOR points at the mark you made on the distributor body.

Rotor pointing at #1 plug wire terminal location on I-6 engine.

4. *IF* your distributor rotor lines up with the mark you made,
The 'Hash' mark on the harmonic balancer lines up with the 0 (zero) mark or TDC mark on the front cover timing scale,
Then the distributor AND the harmonic balancer are both correct and you can proceed.

*IF*... They DO NOT line up at the same time, See instructions below on how to VERIFY the entire ignition starting with finding TDC of the #1 piston and working up from there.

5. Put the distributor cap on your new distributor,
Determine which terminal is going to be #1,
And make a mark on the distributor BODY so you can locate #1 with the cap off.

6. Take the cap off, and put the ROTOR on the distributor, so you can see where the shaft is pointing...
Line the rotor nose up with the mark you made on the housing, and that is all the prep work you need to do with the new distributor for now.

7. Loosen the retaining bolt and make sure the clamp will allow you to remove the old distributor.
Normally, you will have to take the bolt and clamp completely off, but sometimes you will get lucky...

8. As you LIFT the old distributor,
Take note the rotor will move BACKWARDS in the firing order as it moves that first inch or so.
This is due to the rotation cut into the drive gears.

9. Once the OLD distributor is clear, have a look inside your engine with a flashlight and see what kind of shape your camshaft gear is in...
Take a rag with solvent and clean out the hole as best you can.

Oil reside will cause problems with fit many times, but DO NOT use abrasives or sand paper in the hole to clean it!
The last thing you want is sand/abrasives in your engine!

The only 'Abrasive' I would allow is 'Scotch Brite' pad wetted with solvent.

10. Once the hole is cleaned up,
You can lower the new distributor in the hole...
REMEMBER to turn the rotor just shy of one plug terminal space BACKWARD in the firing order (Counter-ClockWise) before you engage the gears...
That should allow your rotor to point directly at the #1 mark you made on the new distributor when it's fully seated...

11. More than likely, your distirbutor WILL NOT seat against the engine block or timing cover if it's a V-8...
The reason for this is the oil pump drive didn't line up with the distributor when it went in.

VERY COMMON, and VERY EASY to fix...
Simply rotate the engine (turning lower pulley, turning belts, using a wrench to turn crankshaft...)
Your distributor will 'Drop' in the last 1/2" within the first 1/2 turn of the engine,
YOU MUST turn the engine over TWO FULL REVOLUTIONS and bring the balancer 'Hash Mark' back to TDC or 0 indicator on the timing scale to check the rotor alignment.

You are working on a 4 cycle engine, that means TWO full revolutions to get back to TDC of Compression stroke.
By doing TWO full revolutions, the rotor will travel ONE full turn, and the TDC mark is your 'Base Line' to adjust from.

After TWO full revolutions, the rotor should be pointing DIRECTLY at the mark you made to indicate #1 plug wire on the distributor base.

*IF*... It IS NOT pointing at the #1 mark when you make the two full revolutions....
DON'T PANIC! It just means you got the distributor dropped in one tooth off.
Happens all the time,
You simply pull the distributor, correct for direction, and drop it back on the camshaft.

If it doesn't seat against the housing or block, Turn the engine two full revolutions again and inspect for rotor alignment.
I've been doing this for 30+ years, and I still occasionally get one in wrong on the first try...
You get to lift and try again as many times as needed to get it correct!

12. Once the distributor is in, and the rotor is pointing at #1 with the balancer 'Hash' mark pointing at 0 or TDC mark, you are ready to tighten things up, put the cap and wires on, and set the timing with a timing light.

You find that the rotor or the balancer don't agree with each other, you are going to need to start from scratch with the distributor placement.

Actually, I recommend doing things this way just so you can VERIFY the entire system from top to bottom!

A. Disable the ignition by disconnecting the small wires to the coil.

B. Remove the #1 spark plug wire and spark plug from #1 cylinder.

C. Turn the engine over BY HAND! DO NOT USE THE STARTER!
It's MUCH too easy to bypass compression stroke when using the starter, and you MUST find compression stroke!

D. Put your finger OVER (not 'In'!) the #1 spark plug hole, and turn the engine by hand until you feel compression stroke starting.

E. Use a Wooden Dowel Rod or Chop Stick (NOTHING METAL!) in the spark plug hole and feel for the piston coming up as you turn the crank BY HAND...
You are feeling for the piston to be at TOP DEAD CENTER (TDC) and you want that piston to be at as close to EXACTLY TDC as you can get it.
If you have to back the crank up and go forward again a few times to find EXACTLY TDC, then do it...

F. NOW, Check the harmonic balancer Hash Mark against the timing cover scale.
It should be within just a degree or two of 'TDC' or '0' on the scale...

AMC V-8 Timing Scale on the front cover.

Once you have...

G. Find and mark the #1 plug wire terminal on the distributor BASE so you can tell where #1 is supposed to be with the cap off.

H. Flip the distributor cap, and see if your rotor is pointing (more or less) at the mark you made on the distributor base.

The harmonic balancer lines up with 0 or TDC mark on the timing scale,
The rotor is pointing (more or less) at the #1 terminal mark you made,
Then you have...


Now matter WHERE the engine is in it's rotation between Intake, Compression, Power or Exhaust stroke,
If you follow the simple 'FIND COMPRESSION, FIND TDC' you will ALWAYS be able to install the distributor correctly and VERIFY the components are all working correclty!
JeepHammer is offline  
post #4 of 5 Old 12-16-2010, 11:26 PM
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1988 YJ Wrangler 
Join Date: Jul 2010
Location: easton pa
Posts: 752
very nice explanation jeep hammer, this will help me out a lot this weekend when i change my distributer

1988 yj. 4.2l with a Weber and an ax15 swapped in
mylightsrsquare is offline  
post #5 of 5 Old 03-19-2013, 12:29 PM
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1988 YJ Wrangler 
Join Date: Dec 2012
Location: Fountain
Posts: 56
many thanks as now I must undertake the great distributor removal of 2013
rubinscube is offline  

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