crank/camshaft timing

[Jens]

Sorry to beat this topic to death but I rather not take things apart and realize after the fact that I did something wrong.

So here is the deal - I have the camshaft end caps off, I have the heads and cylinders off, I have the flywheels off. Looking at the camshaft idler gear combo from the inside of the engine (down the cylinder opening), it appears I have some dimples for timing but they don't seem to come together at a TDC event. Looking from the outside through where the camshaft cover used to be, I see no timing marks. Neither view lets me see the side of the little gear on the crankshaft.
Since the idler gear position is relatively unimportant, how do I ensure that the gear on the camshaft is at the right position in relation to the gear on the crankshaft (especially since I can't see the crankshaft gear).

Things are getting pretty close to completely stripped down. Bits and pieces everywhere .... I sure hope it goes back together the same way it came apart !

Has anyone ever modified the camshaft end covers to seal the hole where the camshaft pokes through ? I would really like to try and prevent oil from oooozing all over once the engine is back together and since there is no seal and since there is very little vacuum in the crankcase, I suspect the engine would quickly blacken up on the outside if I didn't fix this issue.

[akghound]

Well Jens don't worry about the timing. It is easy to get back, just take it apart without any marks.

So engine rotation goes;
TDC – Piston starts down on power,
BDC – Piston starts up on exhaust stroke.
TDC – Piston starts down on intake stroke. This is where the measurement is taken. Place the cam so the intake lifter is .045 inches off of Dead Bottom. Dead bottom for the valve cam lobes occurs when the fuel cam is between 9 o'clock and 12 o'clock. The general area for the fuel cam lobe should be near the 5 o'clock position when the engine is properly timed. At this point the exhaust is closing, almost closed, and the intake valve has just started to open. I still think the timing window is broad, something like .040" to .050" depending on the individual engine.
BDC – Piston starts up on compression stroke.

Be sure to have both of the cam cover housings in place when taking the measurements to time the cam.

Ken Gardner

Here is a link to the procedure posted on The UtterPower Forum http://www.slowspeedengines.com/forum/showthread.php?t=458&page=2&highlight=.040 Refer to posts 19 and 21. There are some pictures posted there as well.

[mike90045]

Here is a link to the procedure posted on The UtterPower Forum http://www.slowspeedengines.com/forum/showthread.php?t=458&page=2&highlight=.040 Refer to posts 19 and 21. There are some pictures posted there as well.

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[Crofter]

If you do take it apart without noting the present timing, all is not lost, however why give up an advantage if you dont have to. The timing marks may not be visible at TDC as the idler / crank gear may be in the way ( they also may be non existent too) Without the heads on it is not so handy to note valve opening points. If you do use any info that uses crankshaft degrees corresponding to opening point, be sure valve lash is set to the specs that correspond to the timing specs. The difference between 17 thou and the 8 thou recommended for the higher rpm engine gives a big variance measured at the rim of the flywheel. Those engines will run after a fashion, being out one tooth, but there is only one correct location as it changes injector timing as well as valve opening.

I think you will find that intake valve lead and lag is symetrical with the throws vertical. That means that the intake lifter should start to open slightly before the piston hits TDC and starts to descend on intake stroke. It should close the same distance beyond BDC as the piston starts to rise on compression stroke.

[playdiesel]

There are items called bearing clam shells that are designed to get behind the race and pull the bearing without damage. Harbor Frieght has them and the quality is good enough for casual usage. You also need a cross bar type puller and bolts long enough to reach the clamshell from the end of the crank shaft. It isbest to leave them alone even with the puller. We maked our 6/1 withthe bearing still on the shaft, I think we used a dremel tool and cutoff wheel to make a mark. How tight they are on the shaft is dependant on which side of the tolorance, big or small the shaft is. Either way they will vary from tight to REAL tight. Since I am not familar with the /2 engines I should probably keep my trap shut but on the 6/1 we double checked the timing the same as we do any other engine. At TDC every other stroke you should have the exhaust just closed or very close to it and the intake just begining to open. One tooth off either way and this will not be the case. It's like things will be right, or way off you wont have to scratch your head about it if youknowwhat I mean?  And if things were right before the measurements Ken posted will be right as  triple check.

Bearing clamshell

[billswan]

Sorry to beat this topic to death but I rather not take things apart and realize after the fact that I did something wrong.

So here is the deal - I have the camshaft end caps off, I have the heads and cylinders off, I have the flywheels off. Looking at the camshaft idler gear combo from the inside of the engine (down the cylinder opening), it appears I have some dimples for timing but they don't seem to come together at a TDC event. Looking from the outside through where the camshaft cover used to be, I see no timing marks. Neither view lets me see the side of the little gear on the crankshaft.
Since the idler gear position is relatively unimportant, how do I ensure that the gear on the camshaft is at the right position in relation to the gear on the crankshaft (especially since I can't see the crankshaft gear).

Things are getting pretty close to completely stripped down. Bits and pieces everywhere .... I sure hope it goes back together the same way it came apart !

Has anyone ever modified the camshaft end covers to seal the hole where the camshaft pokes through ? I would really like to try and prevent oil from oooozing all over once the engine is back together and since there is no seal and since there is very little vacuum in the crankcase, I suspect the engine would quickly blacken up on the outside if I didn't fix this issue.

Jens

The pix below of my 10/1 shows the camshaft and bushing and I also wanted to seal it against leaks. I do not have a pix of what I used but what I did was to use one of those larger red cap plugs that you normally find plugging ports and piping in new equipment. On my engine the casting that holds the bushing was just long enough that the cap plug fit over it using the inside diameter of the plug over the casting. Basically like a condom.  Of course I have no idea if your 20/2 is built so as to use this strategy.

As to your timing question well ........You will have to fight that battle with the help of the other posters.

Billswan

[veggie]

Try this....assuming you have not yet dismantled the valve train and crank.

Rotate the crankshaft until the piston is at Top Dead Center (TDC) on the firing stroke.
At that point, you may even see some marks visible on the idler and cam gears (if not, don't worry).
With the crank at TDC you now have a reference point for the future.
Paint mark the idler and cam gears at the mesh point. (See picture) One dot on the idler tooth and two dots on the cam gear teeth.
The crank being at TDC is the reference point for the crank gear.

When the unit goes back together, as long as the crank is at TDC on the firing stroke and the cam/idler gears mesh according to your marks, everything should be back as it was.

In theory .....

veggie

[Geno]

Veggies method is what I used and it works. If the pistons are out get it close to tdc and scribe a mark from the crank to the crank housing. Then mark the gears.

It's been a while since I've had to time my engine. I marked the gears with a dremel when I first got it. IIRC with the marks lined you have to turn the engine over ~14 times to get them lined up again. This confused me till I realized the gears were different sizes.

My engine came with a cap on the hole in the cam cover. I further sealed it with rtv.

Thanks, Geno

[playdiesel]

My  ignorance is going to show here a bit but your leak is in the area I have put the red line around right? On my Metro that bushing is in just far enough that there is room for a soft plug. If you have the governor housing off the engine off look and see if there is room to knock the bushing in about 1/8" and get a concave soft plug at a place like NAPA. Be carefull that you dont knock it in too far as the plug needs to bottom on the bushing before it hits the end of the cam. My plug was held in place with silicone sealer and that's how I reinstalled it.

[playdiesel]

I realy need to update my digital camera and take a video of timing the cam. All the responces are good but the job is soo much easier than it sounds. A 30 second video would make it all very clear.

[billswan]

Playdiesel, thanks for the suggestion of the bearing puller. I do have a set of those but the problem I was foreseeing is the fact that in order to use it you have to pull the crank out a bit and would probably loose the gear engagement with the idler and then you are hooped.
Sounds as if that is the only way though ......
Looks like I won't bother to pull the bearing. I have no bearing heater for re-install and this bearing is too critical to risk over heating with the torch. I will try to get the timing right based on all the suggestions. Thanks guys ! Wish me luck

Billswan, this setup you are using sounds a bit. um, questionable. I guess that I could possibly use the concept though, make a proper steel cap and RTV it in place. I haven't examined my setup yet to see if I have enough of a boss sticking out of the end cap. ... Thanks !

Jens

Questionable  Ya  you got that right. But I was looking for a CHEAP quick fix and so far it has worked well. But of course I know the plastic will get hard and crack with age but then you just slap on another, cap plug. I don't know if these indian quality roids deserve much more?

I also agree with what Geno wrote about marks only line up once every 14 or so revolutions. That could through a curve to someone not aware of that quirk.

Good luck jens we are all pulling for you. Want to hear of you thumper  back in action this fall!!

Billswan

[playdiesel]

Basically like a condom.  Of course I have no idea if your 20/2 is built so as to use this strategy.

Billswan

I though they were made to fit all "builds"  at least that what is says on the little package LOL

[Ronmar]

jens
   Another way if you don't have timing marks, is to use a dial indicator on the intake tappet.  If I recall the numbers correctly, the intake valve should just start to upen at 5 degrees BTDC, and be open approx .020" by TDC.  There should be only one gear relationship that will get you this result.

My 6/1 didn't have any timing marks, and I read this over on Georges forum way back when, and confirmed it on my engine before I initially separated the gears...   

[akghound]

Bearing removal ... I drove mine off with a punch from the back.


Just a couple taps and it was off.
Ken Gardner

[akghound]

Back to Cam timing ...
Yes one has to remove the #2 pump lobe, file the tapered pin down to the collar on the lobe, be sure to file the small end. Drive the pin out and remove the lobe. The hole is tapered so getting it back in the correct position is easy. Don't to forget to take out the retainer bolt/pin for the center bearing. Pull the spring out of the oil pump and use a magnet to pull the pump plunger back away from th cam. Use clothspins to hold the lifters up off the cam. Now you are ready to slide it out.
Replacing the cam....
It doesn't matter which tooth on the crank gear meshes with which valley on the idler gear, or what ever. Put those two anywhere, any tooth to any valley.
Keep in mind that when we refer to TDC we usually mean the piston is at the top of the power stroke that is of followed by the power stroke.
HOWEVER ... THE TDC FOR THIS PROCEEDURE IS THE ONE JUST AHEAD OF THE INTAKE STROKE Just after the exhaust stroke. Between Exhaust and Intake strokes.
With the #1 at the top of the stroke, position the cam so that the intake valve lifter has raised about .040 inches from it's bottom or lowest position. I use a dial indicator placed on the flat of the block where the lifters protrude through to measure this.The pump lobe should be in the neighborhood of the five o'clock position. In all actually the lifter may not move exactly .040 but will be close to it. One tooth off one way and it lifts much farther, one tooh off the other way and it lifts much much less. Be sure the end caps are on when you take your measurement. After you have it set in the correct position you can then put the pump lobe back on the far end.
I just used some Silicon to seal the caps.
Hope this clears it up some for ya.
Picture of 5 o'clok position. Just so you know the approximate position. You may have to move it a tooth one way or the other.

Ken Gardner