Cam Timing Question

[88911coupe]

OK...following Wayne's book and get everything set up then rotated crank approaching 360 degrees and looked for about .050" which I thought was right in the range. Then I am supposed to move the crank further, with pin removed, to get it at TDC but in my case it appeared to be already perfectly aligned on TDC. Does this make sense or did I probably do something wrong? I put the pin back in and rotated it 720 degrees per the instructions and it's still on 50 degrees so I rotated it 720 degrees again and it's still on. Did I get lucky or do it incorrectly?
BTW, Bentley says rotate either clockwise or counterclockwise but Wayne's book states only clockwise. Any explanation?
TIA

[otto in norway]

Hi there..!
I did my adjustment a little while ago, and there is not much to it, once you understand the big picture.

I did it a bit different than what the book said.

Anyway, here is how I did it:
(I only know metric scale, so you do the math )
1: With the pin in, and the bolt for the cam tightened somewhat, I rotated the crank, and lined up TDC for C#1.

2: Then I checked my valve overlap measurement; I got a value of more than 2mm.

3: Rotated the crank 360 deg, loosened the cam-bolt and took the pin out, chose another hole for the pin, and put it back together.

4: Rotated 360 deg back to TDC, and checked the measurement again; I had moved away from my goal of 1,26 mm. (I have 964 cams)

5: Rotated 360, loosened cam-bolt and pin, picked another hole in the other direction, and put it back together.

6: Rotated 360, deg back to TDC, and I got closer on this measurement.

I continued like this until I found the right hole.


SO:
If you have the right measurement, after everything is tightened down, -I guess you're just lucky!!
But be sure to take multiple measurements, and doublecheck the TDC allignement.
Oh: Turn it clockwise, because you might get slack in the timing chain if you don't!

otto

[911 tweaks]

to just be sure, it is not a bad idea to use a guage to verify that you are truley at TDC... ie the stomski tool that screws into the spark plug hole... this tool has an inner threaded rod that screws down into the cylinder till it hits the top of the cylinder... I have herd of having the cylinder be at TDC (verified with suck a tool) AND the crank pulley being off +/- 1/16" to 1/8" !!
Worth checking out if it was me...
Bob

[88911coupe]

I have the TDC tool so I'll confirm that measurement. I'd been checking with a stiff piece of wire but it does not tell me if I'm off a fraction of an inch or not...just if I'm generally in the ballpark of TDC. Anyway, I posted the question since I was concerned that I did not have to make ANY adjustment after turning it 360 degress and looking for .050 of lift. That just seemed extremely unlikely.

[88911coupe]

Need some clarification with regard to Wayne's book and Bentley. I'm doing the right side and it get's to .050" of lift just a fraction PAST TDC. Bentley says remove pin, then move clockwise OR counterclockwise to get the crankshaft marks lining up with the case seam. Wayne's book seems to imply you can only go clockwise, i.e. the normal rotation method. If I am getting to the target amount of lift AFTER TDC does that mean I'm doing something wrong?

Thanks for the help...

[hcoles]

sounds like you are doing correctly... for some reason(s) it took me a bit to get the hang of this when I did it... then I got the hang of it.... two revolutions of crank pull up to the mark and check dial... repeat. I wish I had one of the TDC tools but didn't. I had the pins in and out probably 10 times before figuring out I was homed in on it.

[88911coupe]

Hcoles,
Thanks for the info...any opinion on the issue of Bentley saying rotate counter clockwise to get it lined up while Wayne's book seems to imply clockwise only? I'm apparently very close to being correct but I don't want to rotate it ccw to line it up if that's the wrong procedure.
TIA

[hcoles]

I think may refer to ccw to get the pin out... I would recommend always going cw right up to the "check" point on the crank and then read the dial ... it shouldn't matter a huge amount of the chain is tight... but just to be safe I always kept tension cw without any ccw movement and then took the reading...

[Eagledriver]

If the chains are held tight with the idler arms then it won't hurt to turn it backwards. In fact that is how I do a quick check to see if I made the adjustment in the correct direction. When you pull the pin out and rotate the crank you are rotating the sproket on the cam to the correct alignment. It doesn't matter which way you have to turn it. I can't remove the pin when the valve is depressed because the cam will rotate when you remove the pin due to the spring pressure from the valve. This is the reason you have to do so many trial and error adjustments. To remove the pin without the cam rotating you have to turn the crank (with the pin still in) until the valve is closed. So you are doing the adjustment blind to a certain extent.

Hope this helps.

-Andy

[88911coupe]

Andy,
Thanks, that's sort of what I was thinking.

[SCrescue]

Buck,
Just went through this yesterday myself and had the same concerns you did. Rotated past 360 degrees from TDC to reach 1.8-2 mm per DC-19 cam timing specs, removed the cam nut/washer, pulled the pin, and rotated the crank CCW to get back to Z1. I concluded that Wayne's book must reference a general procedure for non-performance OEM cams, because I set both cams this way and the numbers are astonishingly repeatable as I cycled through several CW crankshaft rotations. I have two metric indicators set up so it was easy to verify repeatablility from side to side as I rotated the crankshaft through several rotation cycles. For a sanity check, I left the indicators in place to recheck timing after installing new carrera tensioners, numbers remained rock solid.

Mike...

[88911coupe]

Mike, thanks for the info. It looks like I've got mine both timed to about .050". Is there any simple sanity check to check to make sure I've not got anything totally backwards with regard to the cams? I don't seem to be getting any valve/piston contact so does that mean it's done basically correct, other than possibly some error in gettting them at exactly the same amount of lift?
I think I may have done this incorrectly since as I rotate the crank it seems both intake valves are opening at the same time. Sounds like I'm out of sync to me...
I did go ahead and remove the large cam bolts and confirmed the "930" marks are 180 degrees apart. Not sure how the intake valves can both be opening at the same time...
Thanks

[SCrescue]

Buck,
The 930 marks should not be 180 apart, they both have to be orientated in the same direction to be properly timed. Once you get the right side cam properly phased, it will all make sense to you. A side benefit of having two indicators set up is that it makes it easy to the see the phasing from side to side as you rotate through 720 degrees.

Think of it like this: Starting at TDC on #1 (Z1 on parting line, intake valve is closed and can be wiggled due to .004" clearance previously set). At this point, #4 intake will feel tight, as it's beginning to open. Begin rotating CW through 360 degrees and stop at Z1. You should be at, or close to your timing seting (.050") and the intake valve is beginning to open, so you won't be able to wiggle the rocker. At this same point, you will be able to wiggle the #4 intake rocker since it is now at TDC and the valve is closed.

Remember, 720 degrees of crank rotation is one complete cycle through all six cylinders.

Another way to look at it is through the firing order....1-6-2-4-3-5...every 120 degrees (marked on the crank pulley), another cylinder is at TDC, so after 360 degrees, #4 is up in the order. Hope this helps.

Mike ...

[Walt Fricke]

Buck

The sanity check comes from not having valves hit pistons as you go on to install the rockers on cylinders 2, 3, 5, and 6. That insures you didn't get one side or the other 180 (or, if you will, 360) degrees out of phase.

As long as your final measurements, after you have torqued the big nut (or the smallish bolt on later cams), are all made with a clockwise rotation of the crank, it doesn't really matter at all how you got there and which way you turned what to do it.

Me, I set the crank at TDC, and rotate the cam with the tool until I get the reading I want. Then I insert the pin into whatever hole will take it. Then I put the washer and nut on loosely and, if things have moved, turn the cam until they are back to where I want them to be. Then I snug the nut down and rotate the crank two turns and watch to see what hitting the TDC mark will give me on the gauge. Most of the time it is what it was, or close enough. And I can torque the nut, give it one more check, and be done.

There is enough play in the pin setup that you can't count on it alone, and its vernier system, to get you to where you want to be. At least I don't count on it. It is the torque on the nut that holds the timing, not the shear strength of that pin.

As long as you are only dealing with the pressures from one valve spring per cam, this seems to work pretty well.

For that matter, I once opened up an engine in the car, removed the tensioner and cam gear, tightened the three 10mm bolts that hold the aluminum gizmo and its O ring down tight, put the cam gear back on and put the pin in a suitable hole, tightened things down, and got ready to retime. To my amazement nothing had moved! I wouldn't count on such luck, but cam timing isn't really all that tricky. Easy to say when you've done it enough and made a bunch of mistakes learning, though.

One of these days I am going to make a second dial indicator holder - I've got enough dial indicators (latest toy is a digital one - really neat and I can finally use metric readings). The holders you purchase cost more than a dial indicator. Economy of scale at work, I suppose.

Walt Fricke

[88911coupe]

Walt, thanks for the info. I figured out how I got the cams 180 degrees out of sync. I've timed them 2-3 times just to practice make sure I have the process down and now have them both at .050", or very close. I was wondering about your suggestion of rotating the cam to it's proper lift but on 3.2's I don't see how you can get the cam to rotate, other than sticking the bolt is and trying to get it to rotate the cam but then it would really only be effective in one direction, or is there some trick? I checked #1 again after setting #4 and I'm still getting very, very similar readings and the intake valves are opening alternatively. One thing I noticed is that it makes a surprising difference where EXACTLY you rotate the notch relative to the case seam. I could get different readings if I was not dead on as far as lining up the notch with the case seam. It even seems to make a difference which "side" of the notch I'm on!
I'm still trying to forget the sentence in Wayne's book that says "it's important to note that you'll hit the proper amount of lift BEFORE you rotate the crank the full 360 degrees." All three times that I got consistent, good results I had to rotate the crank counter clockwise a few degrees. Several tests afterwards shows both cams still very close to .049" to .050". Hopefully if I did something wrong it will show up in the next step when I check piston to vavle clearance.
Thanks,

[Walt Fricke]

Buck

The vintage of the engines I own is showing here. Sorry for the confusion.

All mine, including the '82 3.0 SC engine, have the old style cams, with the big nut and the flattened cam ends you grip with a special tool (or substitute). So turning the cam is easy and you have full access to the holes as long as the big washer and nut aren't in place. And when they are but only finger tight, you can still move the cam throughout the full range of pin slop.

All of Wayne's pictures but one show this old style setup.

But you don't have that era cam.

I also purchased the tool for newer cams - the tool with three dowels poking out its working surface, which insert into the holes in the chain wheel so you can hold it while tightening the ordinary sized bolt. I thought I'd need that for my 3.0, but I didn't so I have never used it. It sits in my tool box on the off chance that someone at a race will need to deal with a cam and might want to borrow it.

You are right - you'd probably have to figure out a way to rotate the cam with a bolt (I don't think a screw driver on a lobe would commend itself), and that would probably limit you to turning in one direction. Which might work just fine for getting things lined up for inserting the pin into the right hole on your first attempt, if you were lucky enough that the proper hole showed up in the cutout side of the tool.

To use the "rotate the cam" method of dealing with pin slop would require some kind of special bolt whose thread friction could be released without turning the bolt, lest you lose what you gained. Maybe someone with this style of cam has figured out a trick.

Me, I think I'll work hard to keep the old style cams.

You are right about the uncertainty involved it deciding when the crank pulley is at TDC. If you have the alternator housing mounted you have a closer reference and less eyeball parallax. But you worry about the accuracy of the notch in the housing. Most of the time I've had everything on top of the engine off, and use the case seam as a reference. But that's farther away from the pulley notch. An old single bladed razor blade can serve as a way of trying to line things up. I've thought about making a wire pointer and attaching it somewhere, but it would have to be indexed. With a TDC finder you don't have.

The best notion I think is to use the flywheel, assuming the engine is on a suitable stand. You use other methods to determine exact TDC, attach some kind of jig or pointer on the flywheel end of things, and then scratch a mark onto what the pointer is not attached to. Then you watch the mark come to the pointer, or the pointer to the mark. You gain accuracy there because the flywheel has a much larger radius. However, when I tried that I didn't entirely trust it, for reasons I can't remember. Maybe my TDC finding (using a dial indicator before the heads were on) system was at fault. Sounds good, though.

The good news is it sounds like you have your cams where you want them on the dial indicator, and valves aren't hitting anything. The only way you can really screw things up is to have one cam 180 degrees off, and that causes so much interference you can't rotate the crank very far. Which means it is one of those blunders you are very likely to discover before anything worse than a bunch of extra work and lost time is involved. Otherwise, there is a fair range of fine cam adjustment which falls within the factory's acceptable range.

Walt Fricke

[88911coupe]

The razor in the seam seems like a perfect solution. I'll try that tonight and see how things measure up.
I also was thinking of finding some way to get the cam bolt to bottom out on something in the hole and then use it to rotate the cam back and forth but got worried about getting it out of the hole when I was done. So long as I did not cause any problems by rotating the crank CCW a few degrees I think I'm good to go and ready to finish this up.
Thanks

[euro911sc]

Buck,

When I went to adjust the crank to position per the book, my cam turned with it making this task rather frustrating... I tried moving it CCW and had no luck there either, but did not encounter any troubles after doing it so I think, as Eagldriver says, if your tensioners are tight on the chains you should be able to go CW or CCW.

FYI, when my cams moved when trying to move the crank to TDC I set the crank at TDC and used a small screw driver to move the cam, instead, back to the correct lift and then set the pin. A few rotations and a check or two later and I was buttoning up the covers.

Best regards,

Michael

[Eagledriver]

Walt has given you great advise except for one point. Having one cam 180 out (like you had for awhile) will not cause interference on rotating the engine. It will behave perfectly normally except you will have twice as much compression on part of the rotation and no compression on the other part. You could even get the engine to run that way if you had an ignition system that could fire 2 cylinders at once.

-Andy

[88911coupe]

Andy, I noticed that and guessed that's what was causing it. The resistance to rotating the crank spiked pretty high when I had the cams 180 degrees off. Now that I more or less "get it" with regard to cam timing I can see the experienced people on here being somewhat amused at us amateurs.
How I screwed up at first was reading the part about "the mark on the right cam should point down" and I was thinking the other one was pointing up. Good thing I decided to just watch the lifters to be sure.