Valve adjust question - no rocker movement
 

Doing my first valve adjustment. For the most part everything has been going fine albeit slowly (engine in the car). I'm setting the valves with the feeler gauge and then checking with the backside method.

However, on the #2 cylinder exhaust valve and the #3 intake, even with the adjustment screw fully backed out, I could not get the rocker to budge - my method has been to back the screw off three or four turns, create a fairly large gap and then get the gauge in and then tighten down onto the gauge.

I tried rotating the crankcase back to the correct position in both instances - same issue.

Finally, just went to a spot in the cam rotation where I was certain the rocker was not on the lobe and did the adjustment there.

Is there something I'm doing wrong? Any advice?

Does not make sense, are you saying the rocker does have movement someplace else ? In that case, you're not in the correct position where you think things are. The rocker should be "loose" in one position every cam turn. All the rest of the way, the cam should be tight on the rocker. Where its loose has to be the right position. Do some careful looking at your positions and which valve is opening and closing at each 120 degree mark. Sure I'm not explaining this the best way, others are much more experienced.
I kinda cheat my valve job by turning the motor clockwise to whichever 120 degree mark is closest and then going around and wiggling each rocker, if its loose, I adjust it and keep a little log going 1-12. Two more 120 degree turns and you should have checked/adjusted all 12. (I think thats right) I've not had a "tight" valve on my old engine.

With 10 of 12 valves, I was able to back the adjustment screw off significantly so that I could actually get the feeler gauge into the (big) gap created by backing it out a good ways. I need a big gap to get the feeler in.

With the two valves I referred to, backing out the screw would still not allow the rocker to move up and down to create the gap I need to get the gauge in. I double checked the distributor and crankcase reference marks and re-rotated to the correct position each time, but still could not get the rocker to move. Even tried tapping on it (gently). I checked against Wayne's book and Bentley's and even drew myself a little 360 degree diagram with the cylinders marked at the 120 degree marks so I'm sure I was on the correct mark for each valve.

Strange that 10 would go fine and two would give me so much trouble.

In that you were able to adjust the other valve for each cylinder, it indicates to me that it's not a case of the crank rotation being incorrect.

I'm not the expert, but I'll throw out there the obvious, that there is another worn part causing the train to be out of spec - i.e. valve keeper, valve guide, valve seat, valve stem, rocker, rocker shaft... I'm not knowledgable enough to tell you what the most probable case would be - for that I'll let others 'guide' the discussion.

Can you tighten the adjuster down to open the valve slightly then back it out and see if it will move? It would be rare to have the rocker frozen on the shaft. You should be able to see if it's on the low side of the cam pretty easy.


Sent from my iPhone

most people bend the end of feeler gauge or use a 911 gauge

Yeah, this is weird. I went back out to the car to try #2 again.

I've tried backing the adjustment screw all the way out and then going all the way back in.

What's noticeable is that the screw never starts to turn freely - if fact there's a fair amount of pressure on it. It seems obvious that the rocker is on the lobe, the valve is partially depressed and the resistance on the adjustment screw is the force of the spring pressing the valve onto the screw. I can rotate the crank to a random spot where a gap does open up and I can then freely move the rocker, but that spot is not at 240*.

I've re-rotated the crankshaft three times to the 240* point on the distributor which lines up with a mark on the crank pulley. (I cannot locate a Z1 mark on the crank pulley at 0* - if it's there (3.2 Carrera) it is obscured by the AC compressor pulley.

As I understand it 0*equals TDC for #1 and #4, 120* is #6 and #3 and 240* is #2 and #5. O* is under the #1 spark plug wire and the notch in the distributor at that location points toward the fan. Each of the distributor locations (obviously approximate for 120* and 240*) lines up with a mark on the pulley.

As I said, I was also having the same issue with the #3 intake.

Does it sound like the whole camshaft timing is off on the left side? Seems improbable given that the engine ran fine, drew strongly etc. I'd think a bent valve would be pretty obvious to detect audibly.

Surely, I must be doing something wrong?

Pull the dist cap and roll it around till the rotor is pointing at that cylinder, there should be a mark on the pulley near that spot then check the valves for that cylinder.

Also, you can put a wooden dowel into the sparkplug hole. When it is fully out, you'll be at TDC.

The marks on the pulley line up with the case seam or straight up as viewed from the rear of the car. You can only adjust one cylinder at a time for any given crank position. Even though #1 and #4 are at top dead center at Z1, one is at the top of the compression stroke (which is where it needs to be for adjustment) and the other is at the top of the exhaust stroke. Here is how I do it:.

1. Rotate the crank clockwise until you see the intake valve on #1 start to open. Continue to rotate the crank until you get to Z1 or "0" on the crank pulley (the rotor will also point to the #1 spark plug wire).

2. Adjust IN & EX on #1

3. Rotate crank 120 degrees and adjust #6

4. Rotate crank 120 degrees and adjust #2

5. Rotate crank 120 degrees and adjust #4

6. Rotate crank 120 degrees and adjust #3

7. Rotate crank 120 degrees and adjust #5

Thanks Lindy, but I'm doing exactly what you describe EXCEPT-

I cannot verify that TDC on No 1 corresponds to Z1 on the pulley - There is no Z1 mark on the pulley rim that can be seen because of the AC pulley in front (behind) it. However mark on back rim of pulley lines up with mark on fan housing, distributor is in the No 1 position and No 1 adjusts fine.

PROBLEM IS NO 2 EXHAUST AND NO 3 INTAKE ARE ON THE CAM LOBES WHEN THEY SHOULD BE AT TDC after making the necessary rotations of the crankcase pulley. There is firm resistance on the adjustment screw in and out in each case indicating, I believe, that the valve is depressed and the valve spring is causing the resistance.

If there is a difference between TDC for the compression and exhaust strokes (per Lindy's reply) why would Nos 1, 4, 5 and 6 all work fine, but 2 and 3 be out of wack?

Is #2 EX and #3 IN on the lobe or on the cam circle? If they are actually on the lobe you have a screwed up cam. If they are on the circle the stem has become closer to the rocker some how. It could be that the seat is worn or the valve surface is burned.

The TDC you are looking for is after the IN has closed but before the EX starts to open; the compression stroke top. This is the point where the cylinder will fire. One way to tell TDC for #1 is to again watch for #1 IN to start to move. Make a mark on the pulley, then turn 360 degrees. That will put you within a few degrees of TDC #1 compression stroke.

Ok if the cams are installed correctly in the car. We will assume they are the process is simple. Pull all the valve covers off. Unless you have not drained the oil. Put the engine on the Z mark. Check the valves on number 1 and number 4 one side or the other should have both valves loose the other side not. If both sides are loose or tight your cams are out of time. You don't even have to move them up and down just try and see if they wiggle side to side. If you want to do them in order and 4 on the right is loose then rotate the engine another 360 and recheck. Now for the really fun question. How certain are you of the engine. Is it possible that the cams are 180 out. The engine will run that way. I know a guy who ran for two years that way. That would however really screw with your valve adjust method. Also you should not have to back the adjusters out all the way.

If its possible to be on the Z1 mark but not on the distributor mark then it must be possible to be on the distributor mark but not on the Z1 mark (which you can't find).

I experienced this non movement of rockers when I had my car on the Z1 mark but the distributor was 180* off of its mark. I had to go around again to get them both to line up. (I didn't even realize that that was possible!)

I'm not smart enough to figure out if this same scenario would cause your issue but you gotta find #1 TDC. (Z1)

Can you post a pic of your Dizzy when you believe it is at TDC? If you have the patience, maybe pics of all positions, just to make certain???

No mark? strange, I wounder how the PO or wrenches did the valve adjust if there was no mark.

This may sound silly but are you certain the belt on the pully is turning the crank, certain cylinders are tighter than others and it requires you to put some pre-load on the belt to make the crank turn. Just a brain fart.

it sounds like you have adjusted the valves with the crank 180 off, or, you just have very very tight valves.
start over and follow the above. you cant just line up TDC for #1 and go for it.
one other thing, make sure you are adjusting the correct cylinder, IE, if you have the crank set for #2, make sure you are on #2. as of lately, for some reason when i am suppose to be doing #4 i keep trying to do #5. (brain farts i guess). but the dead give away is that the cam lobe is on the rocker.

Maybe you didn't start on true TDC?

OK one more thought. Are you rotating the crank the correct direction . I did this when tired one night and kept going the wrong direction. Drove me nuts (short trip) The result was pretty much as you indicate. You must turn the crank clockwise as viewed from the rear of the engine.

And I forgot to rotate 120* altogether once before moving on to the next set.....

I suspect you are not using Z1 to start with and everything is off from there. Not sure what engine you have, but I seem to recall you have a 3.2. Here is a nice picture showing the correct location of the timing marks:

http://forums.pelicanparts.com/uploa...1088789781.jpg

All good pointers, although as I've said several times, I am correctly following the procedures and, notwithstanding the lack of a Z1 mark on the pulley, I absolutely believe that I am starting at TDC for No. 1 - rockers click and everything is lined up - distributor, pulley mark. I will check to see that No. 4 is not clicking when I get back to it. I always rotate clockwise 120* (that's where the next mark on the pulley lines up) and everything works fine but the two noted. I'm being pretty anal about this - made a diagram, noted positions, checked off cylinders as I went and re-rotated the crank 360* when I ran into the problem.

I did reread the cam timing chapter in Wayne's engine rebuild book last night and looking at the diagrams of valve clearances I got a better understanding of the differences in valve positions between TDC at the top of the compression stroke vs. the exhaust stroke. However, if I were TDC on the wrong stroke, it seems to me both rockers on a particular cylinder would be "frozen" not just one since at the top of the exhaust stroke both valves are slightly open (per Wayne's diagrams).

I also did some more searching and a fellow named Don Ivey started an identical thread back in 2010 that only lasted a couple of posts so I guess he figured it out. I've PMed him and asked what the resolution was for him.

Need to do some "real" work today so will try this again over the weekend.

Thanks for the help for now and I'll either be back with more questions or the answer to the problem. Love this board!

Jim

there must be someone near you that you can invite over for a coffee or beer that will show you or confirm the "trouble"

put out an invite :p

Well so much for Don Ivey's problem. He replied-

"Jim, the resolution was that I wasn't counting the degrees correctly from TDC on number 1cylinder. Somehow I was trying to get all six firing on one rev. of the pully, instead of the requisite two revs. Just go slow, start at the right place, and you should be fine. I felt like a real fool, but realized later everything was alright. Good luck, Don"

I'm going through two full rotations so that's not it.

As I said, I'll try again from scratch this weekend.

Yes, do this - assures you are at TDC and both intake and exhaust cam lobes are on the dwell section. Then check/adjust with feeler.

You really need to stick a wooden dowel on the plug hole of the cylinder that you are adjusting. If the dizzy is pointing to the cylinder being adjusted, and the dowel is as far out of the cylinder as it can be, then you are good to go with the adjustment.

I could be messed up but I think since the dizzy is geared 1/2 rate of the crank, when it points to the cylinder of interest the intake and exhaust are on dwell and not overlap and that cylinder is close to TDC, I don't see why the wood dowel is necessary.

The problem is that we are not sure the cams are timed properly AND the TDC (Z1) mark is not verifiable on the pulley. It's view is blocked by the outer accessories drive pulley. The only way to verify cam timing is to measure it with a dial indicator. At this point I think that's where we need to start so cam timing can be eliminated from the possibilities.

He says that the car ran fine before the attempted adjustment so I'm thinking the cam timing is not the problem. It also sounds like he's got the process down pretty well so I suspect that's not the problem either.

I ask again; at the point in crank rotation where there should be loose rockers, is the elephant foot on the lobe or the base circle (non-lobe part of the cam)? If it's on the base circle there is a dimensional problem with the valve and rocker. If it's on the lobe there is a timing problem.

+1 for NOT sticking wood into your spark plug holes :rolleyes:

This may be the stupid comment/question...

You say this is the first valve job so are you pretty new to 911 motors?
The 911 counts the cylinder numbers different then more common V8s (or pretty anything else). Other cars have the cylinders numbered by crank position from front to rear. The 911 has them numbered 1,2,3 up one side of the motor and 4,5,6 up the other side.

So the question is: Are you really on #2 or are you on #4?

Performing a procedure by the numbers is fine unless you miss a step. At that point you're screwed or at least confused.

The only purpose of going through the step-by-step procedure of starting at TDC is to ensure the valves are closed for the cylinder to adjust. Okay, but all you need to do is to verify each valve is closed before adjusting the rocker arm (valve) clearance.

To do this, merely observe the position of the cam lobe relative to the rocker arm. When the heel of a cam lobe rotates around and contacts a rocker arm, that valve is closed. Simple. Stop. Adjust.

Disregard all the text descriptions on this illustration except for the area at the bottom (base circle or heel).

http://forums.pelicanparts.com/uploa...1320939780.jpg

You'll notice the base circle continues for a several degrees before the rocker arm reaches the clearance ramp at which point the lobe begins to open the valve. And since the cam is driven by the crank (btw, at half speed), the crank doesn't have to be exactly at TDC for the valve to be closed, just pretty much on the heel.

And to avoid physically moving back and forth between top and bottom of the engine (rotating the crank pulley/adjusting two valves, etc.), I would suggest connecting a remote start switch on the starter solenoid. "Bump" the engine to rotate the engine and thus each cam lobe into position in turn, then adjust. Repeat until all valves are adjusted on one bank; bottom left side valves, bottom right side, top left side, top right side (your choice).

Hope this removes the mystery of those "steps" which can get you through a procedure but doesn't necessarily provide insight to some important engine operating relationships.

Sherwood

To 911pcars reply - yes, on the two problematic valves I was able to rotate the crank to a random spot in the cycle that freed up the rocker (allowing it to click). I then made the valve adjustment for the problematic valve doing that. What I found troubling was that the valve wasn't in the "dwell" position (if that's the correct term) when everything else indicated that the cylinder was TDC. Should I not be concerned about this?

As to Lindy's reply in terms of observing the lobe vs. the heel, I can't say I can easily distinguish the two in all instances. If the lobe were perpendicular or nearly so to the rocker (or on the backside "closing" ramp) I think it would be fairly obvious and in this case it wasn't. However, if the ramp of the lobe were just starting to rotate under the rocker, I'm not sure I could tell precisely the difference between heel and ramp given how small the window of vision is and the fact that I'm working under the car, etc. Wish I had stuck a feeler gauge up the backside to check for contact or just looked at other valve positions away from the valve I was working on to give me some reference points.

As I mentioned, I'm going to take another crack at it this weekend and will post the results.

Again, thanks for the help!

To the guys offering counting lessons, I have Wayne's two books, a Bentley's, a Haynes and I spent a couple of evenings reading through dozens of posts on the topic before I tried this.

Wish it were that simple, although that being said, I wouldn't be surprised if this resolved itself on something really stupid on my part. If that's the case, I'll say it now just to get it out of the way - I'm a %$^&* idiot.

Cheers.

Perpendicular to the rocker is all that's needed to adjust clearance. As long as the rocker is not on any part of the ramp or lobe, you'll be OK. My only concern is that if you follow the procedure by turning the crank in 120 degree increments, you should not end up with a rocker on the lobe that is to be adjusted...

Sorry Lindy, terminology blunder - by perpendicular, I meant that the north/south axis of the lobe (the nose) was pointing at the rocker. If that's something other than perpendicular, my bad.

Lindy quote - "My only concern is that if you follow the procedure by turning the crank in 120 degree increments, you should not end up with a rocker on the lobe that is to be adjusted..."

Yeah, me too! If I were comfortable just adjusting the troublesome valve at some random location in the cycle that allowed the rocker to click, I wouldn't have started this thread. It's precisely because something seems out of whack that I'm concerned.

are you trying to line up 0,120 and 240 on the distributor? if you lined up the dist to 240 degrees, that was for #3, not #2.
you only use the distributor to find the compression stroke/TDC for #1. after that, all the referances are done at the pulley.

another possibilty is that you either missed a timing mark or you referanced the 30 degree ignition timing mark.

how did the car run before you started?

i strongly suggest buying the little tool for doing the valves. i tried it with a standard set of gages and it just does not work. i also find it is harder to get a good adjusment buy backing the adjusting screw out, then trying to "start from scratch" and get a setting.

i use the angle of the screw as a reference. if it is too tight, i note the angle, losen the the nut(i will actually turn the screw and nut together, never completely losening the nut), noting the new angle of the screw and tighten the nut making sure the screw angle does not change, then re-check the gap.

if i have to tighten the screw, i losen the nut just a tad, then as i tighten the nut, i turn the screw with the nut.

you really need the tool. once the valves are set, you need to rotate the engine several times then go back and check them again.

The key step in making sure subsequent steps get you to point B is to begin with no. 1 cylinder at TDC ready to fire. Assume this is not an engine just assembled (perhaps timed incorrectly) - it is already an operational engine.

The corresponding marks on the crank pulley and case must be aligned AND the distributor rotor must point to spark plug wire no. 1. If these two items are in synch, the valves for no. 1 cylinder are closed and can be adjusted for clearance.

However, if instead you begin no. 1 at TDC overlap position (intake valve opening/exhaust valve closing), then all subsequent steps will also be off. You'll also notice the rotor instead points to cylinder no. 4 spark plug wire.

From the correct starting point, subsequent crank rotations of 120º will position the next cylinder in the firing order to TDC - ready to fire (check rotor position) and so on. Per the step-by-step procedure, after two complete crankshaft revolutions, you will have adjusted all 12 valves.

A bright work light aimed into the work area helps ID the relative parts in question.

http://forums.pelicanparts.com/uploa...1320949737.jpg

Hope this helps,
Sherwood

jlynch,

The illustration from Sherwood shows the lobe pointing away from the rocker. This is the correct position for then adjusting the clearance. If you are following the steps correctly and are getting rocker contact on the ramp of the lobe (or on any part of the lobe) there is something wrong with the timing of the cam. That can be easily checked with a dial indicator and the Porsche holding tool. It's not easy to adjust the cam timing with the engine in the car but checking the timing is easy. I would do this first and eliminate this as a possibility.

The pulley can only go on one way as it is positioned with a pin into the crank. It can walk a few degrees either way of 0 degrees but not enough to cause your problem.

pull the valve cover and see if the cam is broke, Kevin

That's a good one Kev...