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Pulling a distributor


Leland Davis
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I have a few questions about distributors. The car is a Packard Six, (a 1937 115). Due to sputtering at faster speeds and the recommendations of others on this forum, I have decided to zero in on the distributor first. I started to adjust the gap and found that my old eyes have a difficult time seeing. I am thinking of just pulling the distributor out, so I can check the vacuum advance, and set the points (or replace them) close up where I can see.  I have never pulled a distributor and then reinstalled it before, but I am familiar with what I should do, I think. I suppose that I should mark the timing location before I pull it? I am unsure if the timing becomes ‘loose’ when the unit is pulled. I also figure that I should note the direction of the rotor, and reinstall it in the same position when it is put back. Any thoughts?   Thanks,  Lee

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1 hour ago, Leland Davis said:

I suppose that I should mark the timing location before I pull it? I am unsure if the timing becomes ‘loose’ when the unit is pulled. I also figure that I should note the direction of the rotor, and reinstall it in the same position when it is put back. Any thoughts?   Thanks,  Lee

This is what I was taught by oldtimers over 50 years ago: 

First turn the engine until the rotor points exactly to the front or exactly to the rear, so that you will remember.  (there is a chance that any of us might not get the distributor back in the same day and we forget where the rotor was pointing, so draw a sketch of that when in doubt)

 

next you need a permanent mark on the distributor base right where it enters the engine, and a perfectly placed matching mark on the engine right at your mark on the distributor.  I use a center punch or tiny flat chisel.  If you used an ink marker or paint, the mark may be gone when you clean the parts later.

 

Most important, do not turn the engine over while the distributor is out, as all the above steps won't correct that mistake.

 

  The above steps will allow your distributor, rotor, and initial base timing to end up exactly where it was before you removed the distributor.   After the car is back to running, then you need to do the final timing adjustment by the book specs.  But at least it will start if you are where it once was.

 

One other thing that you must check on the distributor, either right now, or when it is removed; is to check for excessive slop in the distributor shaft bushing by grabbing the rotor and pushing it side to side.  If the bushing wear is excessive, the points won't be stable at all RPMs and the dwell will be affected, (which can cause ignition misfiring issues).

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I have found the easiest way is to make match marks on the engine block and distributor body, and also on rotor and distributor body, before removing it from the engine. That gives a good reference point for reinstalling it and saves time and aggravation trying to set timing and start the engine. A center punch mark, dab of paint, sharpie marker, any will work well.

 

If you have access to a distributor machine and specs to give the operator, that's the best way to go as it can uncover goofy problems you might not otherwise notice.

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The only thing I would add is if you rotate the engine to the starting timing mark on the compression stroke, you don't have mark the base of the distributor and the crank pulley to the engine block AND you have a go-to way of repositioning the engine even if you need to or accidentally rotate the engine while the distributor is out.  You can then just rotate the engine back to the initial advance timing mark but again make sure that #1 cylinder is on the compression stroke.  If you do it this way you should see that the rotor is positioned under the number 1 spark plug wire terminal on the distributor cap.   

 

You can make sure you are on the compression stroke by watching the valve movement on #1 cylinder.  First you will see the #1 cylinder exhaust valve open and close immediately followed by opening and closing of the #1 cylinder intake valve.  When the intake valve closes you then start the compression stroke and you should be watching for the engine timing marks to come into alignment, be it marks on the flywheel like my 31 Buick and many others of the era or a timing mark or marks on the front of the engine near the crankshaft pulley.  Continue to rotate the engine just enough to line up the initial timing mark and you will be at the #1 cylinder firing position.  You can also take a cellphone picture or mark the position of the rotor on the the edge of the distributor cap ledge of the distributor before removing it to make sure you get the right teeth of the camshaft and distributor lined up.  Verify when you put the distributor cap on that the rotor is pointing to the #1 plug wire terminal on the cap. If you don't do it this way and the engine moves while the distributor is out you could get the marks on the crankshaft pulley lined up again but 360degrees of crankshaft rotation out of time with the distributor. 

 

The 4 stroke engine makes 2 full revolutions for each combustion cycle meaning the crankshaft marks can be aligned on either the stroke or cycle you originally marked or the opposite cycle or stroke.  I.E. If you rotate the engine to TDC #1 on the compression stroke and mark the crank to the block then continue to rotate, the next time the marks will line up will be 360 degrees later at TDC #1 on the exhaust stroke, not the compression stroke.  You have to rotate 720 degrees to get from TDC #1 on the compression stroke back to TDC #1 on the compression stroke. 

 

I always position the engine on the compression stroke at the initial or starting timing mark if I  need to get the distributor out of the car to work on it.  It's so much easier to accurately set breaker point gap or if you have dual points set both gaps.  You can also do a better job of inspecting and repairing the distributor on the bench where you can see and work without dropping small parts.  You can carefully bend stationary points to get good alignment.  Then when I put the distributor back in I just make sure the rotor points to the #1 distributor cap terminal.  Then I can set exact timing by putting a 6 volt test light or volt ohm meter across the points with condenser and primary coil wire disconnected and rotate the distributor until the points just open signified by having the test light go out or the ohm meter reading an open circuit.  In the absence of a test light or ohm meter go ahead and connect the condenser and coil primary wire, then switch the ignition on and hold the distributor end of the hight tension coil wire near the engine block and rotate the distributor until you get a spark.  If the initial or starting timing marks were lined up and you find the position that the points just open you can just tighten the distributor and the engine will be timed correctly.  

 

 

On 30's Buicks (this is a 1931) there are timing marks on the flywheel that are viewed thru a cover on the bell housing.

Dist 3388 021.jpg

 

Buick timing to fire #1 cylinder is 11 degrees before top dead center on the compression stroke.  I always put the engine in this position before I remove the distributor.  The distributor rotor SHOULD be pointed so it is directly under the #1 spark plug wire on the distributor cap.  Assuming it is and I leave the engine in this position I can remove the distributor to repair it.  Then dropping the distributor back in only requires the distributor and camshaft gears are indexed to put the rotor back under the #1 spark plug terminal on the distributor cap.  

Dist 3388 022.jpg

 

Now I can put an ohm meter (shown) or test light across the points before connecting the condenser or coil and rotate the distributor until the points just open signaled by a high ohms reading on the ohm meter or test light going out, then lock down the distributor and the initial engine timing is set correctly.   If you don't have either an ohm meter or test light go ahead and reconnect the condenser and primary (small wire from the points) to the negative terminal on the coil.  Then turn the ignition on and  hold the high tension wire that goes from the coil to the distributor cap near ground on the engine and rotate the distributor until you get a spark from the coil wire.  The spark occurs when the points just break.  Tighten the distributor down and turn off the ignition and reassemble the distributor cap and you are ready to go. 

 

Note also in this picture the rotor on this Buick is pointed right at the engine block and with the timing set for #1 cylinder the rotor tip is just behind the distributor cap clip which places it exactly under the #1 sparkplug terminal on the distributor cap.

Dist 3388 023.jpg

 

 

Edited by Str8-8-Dave
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I'll admit, I don't know much about these engines. After reading this thread it seems to me like the best solution would be to buy some good reading glasses and a good work light so you could avoid removing the distributor. No need in opening a new can of worms unless you have to.

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Nothing to fear, the advice above is good.

 

Make a match mark, take a picture, do something to get you back to close to the original position. Start it up, warm it up, and re-time the engine once the work is complete. If you have to roll the engine, just set it to the timing mark (4-8 BTDC, depending on the head, if I remember correctly for that car), and put the distributor in. If the rotor is about 180 away from the #1 plug wire, pull it out, rotate 180, and drop it back in.

 

Two bolts to remove and a pinch bolt to loosen (held by a screw) to disassemble. There are springs under the bolts, watch out for them. Also a good time to clean up your fuelizer (I think that was Packards term) and make sure it’s set at zero.

 

I’m not that old (no reading glasses yet), and it’s much easier to work on a distributor on the bench.

Edited by Ken_P (see edit history)
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