fordmerc

Timing –still!

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Timing  was "off" on my ’41 120. After  the engine was rebuilt it ran well for 800-1000 miles, then the problem gradually became worse, and can not now be fixed by moving the distributor. Based on timing light, after maximum distributor movement I would need another 15 -18 degrees of movement to set the timing correctly. I even tried moving the spark plug wires  in the distributor, to no avail.  

 

I have finally removed all to visualize the timing chain.

 

What I have is the o mark on the camshaft gear is 180 degrees away from the o mark on the crankshaft gear when the crank is on #1 TDC per the harmonic balance mark. At this time the #1 cylinder is on its compression stroke as tested by air blowing into my eardrum from the plug hole. The valves seem to be opening and closing at approximately the proper time in the cycle.

 

I don't understand what is happening. Oil pump shaft failure and rotation has been suggested.

Any comments will be appreciated. What should I do next?

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What do you know about the camshaft, ie: original reused, n.o.s., aftermarket replacement, or ??? I am curious if the camshaft gear is keyed to the camshaft, or not. If so, is the key partially sheared?

I realize that you have had your distributor checked. Perhaps another set of eyes on it to verify might help. My offer to check it over still stands.

Good luck.

Tom

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This might be a stupid question but if you rotate the crank 360 degrees, are the alignment marks closer? Presuming the key has not sheared and since the two sprockets are obviously not 1-to1, it might take several rotations of the crank to get them to align. I'm sure you thought of that but I wanted to verify that you had done it.

Edited by Packard Don (see edit history)

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I do not understand how the situation can get gradually worse unless something is progressively slipping, such as a sheared off woodruff key on the cam gear.

 

From what you describe, it sounds as though the valve timing is timed so that the marks align when No 8 cylinder is firing, although I do not know how that has been achieved. However, the relative position of crankshaft and camshaft may well still be correct. From your description above, if you have the 'O' marks apart, turning the crank through 360 degrees will bring them together. Then you just need to ensure that the distributor is inserted such that the rotor arm is pointing at the relevant plug lead for the cylinder that is firing (ie approaching TDC on the compression stroke). If you look in the tappet chest, when the valves on no 8 are 'rocking' between exhaust and inlet opening, No 1 will be firing.

 

I am however, concerned that you have a probelm that is getting worse. I would therefore remove the distributor and check the the gear on the end of the shaft(which meshes with the camshaft skew gear) is not slipping on the distributor shaft. I think it is secured by a cross pin. (When replacing make sure it engages with the oil pump drive correctly). If all is well there, since you have the front cover off, I would remove the cam gear and check that the woodruff keys for both cam and crank gears are intact.

 

I hope this makes some sense. Please let us know how you progress.

 

Adam..

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Cam timing and ignition timing are two different things. Turn the engine over until the 2 0's are adjacent to each other. This may take up to 4 revolutions of the crank. If these marks can be made to line up they are correct and you can forget about them. If not then somehow the cam gear has slipped and you have bigger problems. Now, turn the engine over until #1 is at TDC on the compression stroke. Ignore the 0's on the cam and crank. Take the cap off the distributor and ascertain that the rotor is pointing to the wire leading to #1 cylinder. If it isn't, loosen the distributor and turn it until the points are just beginning to open with the rotor pointing to #1. Then visualize the rotor turning thru a full revolution and determine whether the ignition wires are running to the proper plugs according to the firing order.

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I can align the “o” marks when the #1 cylinder is on exhaust stroke TDC, i.e. after I have rotated the crank 360 deg. and when the rotor points to #8 cylinder. When the #1 cylinder is on compression stroke , the distributor rotor is pointing to the contact for the #1 cylinder, thus I think I have met Restorer32’s criterion for forgetting about it (great!)

At rebuild, the original camshaft was  used.

I have not removed the distributor again, but that warrants another look and another set of eyes. I will not check the cam key yet since that is another vertical glass wall for me to climb.

Is there any reason to blame some progressive abnormality in the oil pump shaft (as in the potential distributor shaft problem)?

Thanks to all for your help, and yes, Adam, all comments make sense.

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For your last question, the oil pump is where the gear is attached that drives the distributor so you can check it to be sure that the drive pin is intact. Be sure you have a new gasket before reassembly. If you can bend yourself at the proper angle of have a small mirror, while the pump is out, try to get a look at the mating camshaft gear too or maybe you'll be able to see it easier through the distributor hole.

Edited by Packard Don (see edit history)

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The oil pump gear inspected through the distributor hole look OK.

Rotor points toward #1 distributor contact at TDC, but points open later (by 12-15 deg).( EXACT TDC for me  means as best I can determine with a wire in the plug hole and the timing mark which coincide)

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Where are the timing marks on a '40 Packard ? I forget. Flywheel or harmonic damper? I think we are getting close to solving your problem.

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Wherever they are you need to determine when #1 is supposed to fire, likely about 5 degrees before TDC. Align the pointer with the 5 degree BTDC mark, wherever it is. Now rotate the distributor until the points are just barely beginning to open. Lock down the distributor and if you have fuel and spark and compression the engine now HAS to run.

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... EXACT TDC for me  means as best I can determine with a wire in the plug hole...

I don't have a 282 to look at but for the post-war Packard straight eights, the plug hole is not over the piston... it's over a valve.  

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I am  painfully aware that the plug hole is not over the piston, but I bent a copper wire so that when the piston "should be" at TDC, the wire jumped . Best I can do without removing the head.

Now, the engine does run, albeit a bit roughly. My problem is that I cannot rotate the distributor  far enough to get #1 to fire at 7 deg BTDC; #1 fires at about 12-15 deg ATDC  - on the way to becoming a smoother running engine. Changing the position of the wires to the plugs did not help.

My distributor has a fixed relationship to the block that allows only an approx. 23 deg rotation. I understand that there is another model of distributor that is  more variable because it is  held only by a clamp.

I do not mean to reject  comments which I appreciate; I am just trying to solve a problem from the point of an amateur with limited  mechanical background, but a desire to learn.

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Moving the wires over gives you a change of 45 degrees so you'll then be off in the other direction. You may have to try to move the oil pump gear by a tooth which will be tricky but I can't imagine why you would have to do it if the engine was running smoothly at one point and not disassembled since then.

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In your first post in this thread you said "I don't understand what is happening. Oil pump shaft failure and rotation has been suggested". Aligned with Don's comment in the above post of "You may have to try to move the oil pump gear by a tooth which will be tricky" and his comments in Post #8, I suggest you remove the oil pump, that's the easy part, as Don said the tricky part is its installation. For that, have a look at Paragraph 4 of my PackardInfo Project Blog in this post - http://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=2179&viewmode=flat&order=ASC&type=&mode=0&start=472

Check that the pin in the oil pump shaft hasn't sheered or bent and affected the alignment, doing that at least will give you peace of mind that it's NOT that.

 

Here's an interesting thread from PackardInfo about a 282 oil pump shaft pin sheering. - http://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=17077&forum=4

Edited by Ozstatman (see edit history)

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OK, "In for a penny, in for a pound (or dollar?)"

I am going to have another pair of eyes look at the distributor first, then on to the oil pump adventure. Hopefully any defect will be evident on inspection.

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Hi Fordmerc

 

I think you are pretty close to solving the problem now by following the advice above. Others have covered the oil pump drive in some detail, so no need for me to repeat it all, but from what you describe, I think your distributor drive (also the oil pump drive) is one tooth out on the camshaft skew gear. So if you check it as described above by Ozstatman, you will be able to move the gear drive around one tooth to put the ignition timing into the range of adjustment that you need. Throughout all of this, you will need to take note (and write it down !!) which way the distributor shaft rotates when the engine is running, so that you can move it in the right direction. Also, check the integrity of that crosspin.

 

The marks on the camshaft gear seem to be made 180 degrees out, hence they align when No8 is firing, but that is academic, since you can time the distributor to it wherever the valve timing is.

 

I hope you get it sorted out soon. Please let us know.

 

Adam..

Edited by Alfa (see edit history)

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