Ignition Timing

[johnfal]

I have managed to get my hands on a fairly decent timing light with RPM metering etc. Having set it up as per the instructions that came with it and the instructions given on this site for basic timing I end up with the timing mark on the engine and the pulley being miles apart. Using the ADV setting on the timing light and adjusting until I get the timing marks together I get an advance of 50 Deg. My common sense says this is wrong, the engine should not run at this setting.

By turning the distributer I can move the timing mark as expected but I currently have the distributer turned as far as I can clockwise (looking from the top) but the timing mark on the pulley does not come anywhere near the static mark on the body. However with the distributor in this position my starting and idling are significantly improved but not in my opinion perfect

The timing mark that I am using on the pulley is a V groove that has been machined across the flat face of the pulley. I do not know if this is the correct mark as I cannot find a picture or sketch of what the mark should look like.

Any thoughts guys??

[rickf]

If it were 50 degrees advanced you would not be able to start it, it would kick back. Are you sure you are using the right plug wire?

Rick

[muttguru]

By turning the distributer I can move the timing mark as expected but I currently have the distributer turned as far as I can clockwise (looking from the top) but the timing mark on the pulley does not come anywhere near the static mark on the body. However with the distributor in this position my starting and idling are significantly improved but not in my opinion perfect
Any thoughts guys??

John,
It is possible to have the distributor mis-aligned for two reasons.

The first and easiest one to correct is when the intermediate distributor shaft (a short extension of the drive bar) is placed in the engine 180 degrees wrong. What happens then, is that the engine will not fire, because everything is 180 degrees out. So amateur mechanics swap around the ignition leads in the distributor cap to compensate for the 180 degrees. What SHOULD happen is that the distrubutor is removed and then the intermediate shaft is withdrawn and re-installed with a 180 degrees rotation.

Much more difficult to correct is when someone has removed the oil-pump, which also mates with the distributor drive. When the oil pump is removed, it must be re-installed exactly as per the TM. If the Manual is not followed, then the oil-pump can be inserted in one of several positions. This affects the location of the distributor, and subsequently, the rotor arm....it points at the wrong angle at TDC.
This misalignment can usually be compensated for by rotating the distributor until the rotor arm aligns with one of the distributor cap segments. This is then selected as No.1 spark-plug segment and the other three leads are connected accordingly.
But it doesn't always work out as fortunately as this. Sometimes, the location of the oil-pump means that there is little or no adjustment for the distributor, because the shape of the distributor prevents further adjustment - it catches on the engine block. It sounds like this is your problem.

To confirm that this IS the problem, take out the distributor and the intermediate distributor shaft. Turn the engine crankshaft until the piston is at TDC of the COMPRESSION STROKE. Now look down the distributor mounting hole using a torch if needed, and note the position of the oil-pump drive tang (raised notch). It should match the angle shown in the TM. If it isn't in the right position, then you will need to remove the engine sump-pan and re-locate the oil-pump. You must follow the TM to do this properly, because as you insert the pump, the driveshaft of the pump actually turns so that it can mesh with the camshaft. This means that if the tang looks to be angled correctly before you re-insert the oil-pump, it won't be when the pump actually bolts in place in the engine. You must allow for the rotation of the oil pump shaft as it meshes with the cam. The TM explains how to compensate for the rotation before the pump is inserted in the engine.

If the oil pump looks like it is correctly installed, here's a simple method of "static" timing the engine. Once you've got it close enough, then you can use the timing light.
Here's how:-
Check the ignition timing as follows (STATIC TIMING):-
1. Take out ALL the spark plugs.
2. Remove the valve cover.
3. Remove the distributor cap.
4. Stand at the front of the vehicle looking into the engine compartment.,
5. Put your hands on the fan-blade and turn the fan CLOCKWISE (as you are looking at it).
6. While doing this, watch the TWO valves on number 1 cylinder (the one nearest to you).
7. They will go "down" in turn, but there will be a phase when both valves are "up" (closed).
8. As soon as they both look closed, turn the fan ANTI-CLOCKWISE 1/4-turn.
9. Get a thin welding rod (or wire) and insert it into the No 1 spark-plug hole (nearest to you)... you should be able to "feel" the top of the piston.
10. Get someone to turn the fan-blades again SLOWLY, CLOCKWISE.
11. "Feel" the welding rod rise up as the piston comes up to the top of the cylinder (both valves closed).
12. When it stops "rising", that is Top-Dead-Centre.
13. Check the pulley again....look at the edge of the pulley where the pulley-edge has passed the timing pointer (about 1/4 inch beyond the pulley). (This is 6 degrees before-tdc which is the correct engine timing) .Usually, there is a slight "notch" on the edge of the pulley, as if someone had drawn a hacksaw blade across. You have located a notch on your pulley, but I wouldn't put it past a VN mechanic to have cut his own notch on the pulley!
14. When you are happy that you have a good idea of where the notch is or should be, align the notch on the pulley with the pointer by turning the fan-blades through 180 (or 360) degrees CLOCKWISE. Make CERTAIN that the No.1 piston is at the top of the cylinder and that the pair of valves on that cylinder are still CLOSED. Turning the engine 180 or 360 degrees clockwise avoids any errors due to backlash between the timing gears.
Now just have a quick look at the distributor rotor arm. It should be pointing towards cylinder no.1, and when the distributor cap is replaced, the tip of the rotor arm should be immediately under the spark-plug no.1 lead.
If the rotor is facing ANY OTHER segment, let me know, as this will be evidence that the distributor is "out" of correct alignment.

[johnfal]

Hi Guy's, firstly many thanks for the nice welcome and for the quick and very detailed response to my query. My gut instinct on this problem is exactly as Ken states which is that the the oil pump has been installed a tooth or two out. I have an American colleague who I work on the jeep with at weekends (when he is available) and we had more or less come to the same conclusion but we did not know how to prove it.

Given all the detail provided by Ken I will attack the problem over the weekend and see what I get. I get home too late to play Jeeps at night and with two very young kids (yes even at my age) I have parental duties that I must perform for the good of my family and preserve my jeeping hobby for the future. With a bit of luck if Art comes to help at the weekend there will be two of us to tackle the problem and two brains on the matter.

I really am surprised that the Jeep ran at all but it did manage the drive from Saigon to my house which is nearly 30km without any problem but I knew it was running a bit rough and a bit noisier than it should when I drove it part way (I don't drive in Saigon it is suicidal). However having read many articles on this site I thought that it just needs setting up and I could easily do that. Anyway the first thing I did was check everything in detail and discovered that the gap on plug 4 was nearly closed up and the other three were out of spec so I adjusted the gap on those too. I removed the distributer cap and checked the internals, the distributor cap was broken with a large chunk out of it near one of the terminals, two of the contacts inside the cap were showing evidence of contact with the rotor, the carbon contact in the centre of the cap was nearly worn flat, the rotor seemed to have excessive rotational play and No 3 plug lead was nearly broken just above the plug. My distributor is the Swiss Control type.

I replaced the plugs with new, I replaced the distributor with a second hand one which was in very good condition. When I took the original distributer out I found that the lower end socket of the intermediate shaft had been home made and welded to the upper part. The slot in the home made part was too wide hence the excessive rotational movement, it was also too short making a pretty poor fit, so I replaced that too and then I fired it up and the improvement was significant and noticeable.

I then did the valve clearances, they were not too bad just a few minor tweaks needed.

The next item tackled was the carburetter as there was a strong smell of fuel when she was running. The carb is a Zenith model 13660B I reset the float distances as specified as they were well out. I do have another Carb a model 12848 which looks to be in pristine condition but I did not know if I could use it on my vehicle so it is still lying on the work bench.

This tweak improved the running a little bit more so I took it out and gave it a good road run and got her up to about 50mph (if the speedo is accurate). So now all I am left with is the ignition timing problem and that will be my next task. Currently she will start with a couple of turn on half choke without having my foot on the accelerator and she will idle quite well for maybe 5 mins or so then it will stop and can be a little slow at restarting despite being hot and no choke.

There are still other issues to be dealt with such as the transmission and the drive trains and differentials but I want to get the old girl ticking over nicely before attacking them. Oh I managed to get a second hand flywheel cover and get it installed so my clutch is protected from all the muck from the dirt tracks that they call roads around where I live.

Regards
John

[ldj1002]

I time all my vehicles using a vacuum gauge.

[rickf]

Here we go again!

[Rainman]

Hey John,
This is a quote from another thread on timing an M151. "A vacuum gauge will get you close on a V8 but these four bangers with their very low compression will not give a stable enough reading to time it by".

http://g838.org/viewtopic.php?f=3&t=3215&p=27514#p27514

Rainman

[rickf]

Like I said........

[johnfal]

Ken,

[quote]Turn the engine crankshaft until the piston is at TDC of the COMPRESSION STROKE.

I have been reading your very detailed procedure for checking that my distributor is correctly installed and I have one question. Am I right in assuming that it is No1 piston that I must bring to TDC before checking the alignment of the oil pump drive tang? I am trying to make sure that I have your instructions clearly in my head so come Saturday I will will know precisely what I have to do.

John

[rickf]

Number one has to be TDC on the firing stroke, not the exhaust stroke.

Rick

[svramselaar]

hello

short saying

if the valve cover and ignition cover are off
turn the engine clock wise till the
4 cill valve`s are at the point one up one down
same time 1 cill the valve`s are standing stil
you are at 1 cill spark so the rotor finger must be to the first ignition cable (TDC)
now you must are about 6 degree further as the ignition point


george

[rickf]

Another way to tell is that both valves on that cylinder will have a little play in the rockers, you will be able to fell a little tick when you move them. The absolute easiest way to do it is to take out number one plug and have someone bump the starter while you hold your finger over the hole, when it starts to blow your finger out of the hole then just continue to rotate the engine by hand until you get to the mark.

Rick

[johnfal]

Rick/George,

Thanks for the additional feedback it makes the procedure much clearer to understand.

This morning around 6am I spent sometime getting ready to post my first picture, I was in preview mode and just going to press the submit button when they cut the electricity and I lost everything, expressions like "Fcuk" and "bar stewards" come to mind. It is one of the drawbacks of living here but it is so frustrating because they give no warning.

John

[johnfal]

You should never confuse a Mutt with a Willys. First thing Saturday morning at 0530hr's I got the Mutt over the pit dived underneath to remove the oil sump, looked up with tools in hand only to exclaim WTF is it.

I had everything planned in my head as how I was going to do this, I had dry run the excellent instructions you guys gave me so many times except for one thing, I assumed that sump was as accessible was a Willys so it was only a matter of draining the Oil, dropping the sump and wallah straight into the oil pump. Doh!! did I feel stupid, then it sunk in that I would have to remove the engine to do this simple little task and because I had no means of lifting the engine the plan for the weekend had to be abandoned, instead I changed out the rear diff (see separate topic) and UJ's from the gearbox to the wheels.

However the jeep starts OK and is running not too bad so I decided I could live with it a bit longer before setting it right. Anyway the guy I bought the Jeep from is supposed to be coming tonight to take the jeep away to repaint it and change the stencilling to make it look a little more authentic than it is and to patch up the bits that got scratched when I tried to go between two concrete gate posts that were not as wide as I thought, (another lesson learned the Mutt is wider than a Willy's).

At the same time I will get him to fit a new oil pump, re-do the ignition, replace the gearbox with a reconditioned unit and change out everything inside the clutch housing except for the clutch which looks OK. Maybe I will get him to change the clutch too, they are not very expensive.

You may wonder why I am replacing items rather than just fixing the originals, well it is simple, I want to maximise road time rather than have the vehicle sitting idle whilst I take something off, find out what is wrong, try and find the parts then put it back together and trying to fit it in with my working and family hours. I can then recondition the removed parts at my leisure and when they are done they go on the shelf as working spares.

I am even now tinkering with the idea of rebuilding a spare engine just for fun. Acording to ther guy I buy my parts from he can supply all new parts for an engine under 1000 USD but if I wait for a further month I will be able to do it cheaper as he will be importing engine parts from Taiwan where the Military still use Mutts. Some of the parts I have been buying already are Taiwan made and look to be of good quality.

Finally can anyone give me a typical price for a new NOS wiring harness in the states??

John