Valve adjustment questions
03-27-2012, 05:39 PM
#1
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Valve adjustment questions
Hi, all
I am in the middle of my first ever valve adjustment. My question is I went through the first round of valves and found a lot of tight valve clearances. Adjusted all the valves and started back at #1 cylinder and I couldn’t get the feeler gauge back in both valves. I readjusted and went to the second set of valves and they were ok. That’s as far as I got last night. Wondering why and how they would tighten up after one rotation. I assume it is an error on my part. Another question on the “feel” of the gauge as it is slid in and removed. I read that you should feel some resistance once in place and adjusted. I think I have that required resistance but with nothing to compare it to I just am not sure they are right. Any help with this would be appreciated. I don’t want to have to do this twice.
TIA
I am in the middle of my first ever valve adjustment. My question is I went through the first round of valves and found a lot of tight valve clearances. Adjusted all the valves and started back at #1 cylinder and I couldn’t get the feeler gauge back in both valves. I readjusted and went to the second set of valves and they were ok. That’s as far as I got last night. Wondering why and how they would tighten up after one rotation. I assume it is an error on my part. Another question on the “feel” of the gauge as it is slid in and removed. I read that you should feel some resistance once in place and adjusted. I think I have that required resistance but with nothing to compare it to I just am not sure they are right. Any help with this would be appreciated. I don’t want to have to do this twice.
TIA
03-27-2012, 06:21 PM
#2
They wouldn't.
Make sure they the tappet (i.e. the valve tip were it contacts the end of the adjuster screw) is not just sticking on the film of oil. Pull the rocker back and recheck the lash.
If that was not the case then it was likely adjusted incorrectly. It's a little bit of a tricky touchy feely thing to get a spot on valve adjust on a 911 engine.
Correct. It should have an ever so slight drag on the feeler guage, and there is no margine for error, sloppiness, or "that's good enough". The correct adjustment is exactly 0.1mm .004inch. +/- zero.
When I do it I let go of the guage so there is absolutely no twist or induced angle on it to give a false reading, and the pick it up again adjust it, check, release the gauge and check it one more time just to be sure.
If you are not sure they are right run through them again. It is much easier to run through the valve adjustment than it is to put it all back together only to hear a valve ticking and have to start all over again.
It took me a few times before I got a spot on valve adjust down pat.
It is also possible to get the guage in a place where it feels like it is in correctly but actually misses the gap and you get a false reading and end up with one too tight.
It's kind of like doing brain surgery... only blindfolded.
Make sure they the tappet (i.e. the valve tip were it contacts the end of the adjuster screw) is not just sticking on the film of oil. Pull the rocker back and recheck the lash.
If that was not the case then it was likely adjusted incorrectly. It's a little bit of a tricky touchy feely thing to get a spot on valve adjust on a 911 engine.
Correct. It should have an ever so slight drag on the feeler guage, and there is no margine for error, sloppiness, or "that's good enough". The correct adjustment is exactly 0.1mm .004inch. +/- zero.
When I do it I let go of the guage so there is absolutely no twist or induced angle on it to give a false reading, and the pick it up again adjust it, check, release the gauge and check it one more time just to be sure.
If you are not sure they are right run through them again. It is much easier to run through the valve adjustment than it is to put it all back together only to hear a valve ticking and have to start all over again.
It took me a few times before I got a spot on valve adjust down pat.
It is also possible to get the guage in a place where it feels like it is in correctly but actually misses the gap and you get a false reading and end up with one too tight.
It's kind of like doing brain surgery... only blindfolded.
03-27-2012, 07:27 PM
#3
Nordschleife Master
I backsided them. Doing it the traditional way gave me zero confidence I was getting it "right" so I ditched that method after the first couple cylinders I attempted.
03-27-2012, 07:32 PM
#4
The problem with "backside" method is the rocker ratio is 1.45:1 (which has been measured at 1.40:1 to 1.47:1 out to as far as 1.50:1(so how to do you know?)) and is not sufficiently accurate for adjustment.
It means that if you use a 0.1 mm / .004 guage at the cam you will never end up with the proper lash at the valve. It is an impossible dream.
You just have to lean do to it the correct way. The only ONLY other way I know how to do it properly is with a dial indicator.
It means that if you use a 0.1 mm / .004 guage at the cam you will never end up with the proper lash at the valve. It is an impossible dream.
You just have to lean do to it the correct way. The only ONLY other way I know how to do it properly is with a dial indicator.
03-27-2012, 07:39 PM
#5
Rennlist Member
^+1
It's maddening, expecially on the topside passenger side... hard to really get in there and get the right angles sometimes. Also the foot of the tappet can be funky..
Remember to rock the rocker back and forth to make sure it's loose, (on the correct cylinder) and make sure your shim is clear of any creases. Sometimes we wrinkle or otherwise beat them up, and that affects the ultimate adjustment. Either have fresh shims or new stock available.
It's maddening, expecially on the topside passenger side... hard to really get in there and get the right angles sometimes. Also the foot of the tappet can be funky..
Remember to rock the rocker back and forth to make sure it's loose, (on the correct cylinder) and make sure your shim is clear of any creases. Sometimes we wrinkle or otherwise beat them up, and that affects the ultimate adjustment. Either have fresh shims or new stock available.
03-27-2012, 07:50 PM
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03-27-2012, 08:35 PM
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Guys,
That is exactly the information I was looking for. Vandit could you please explain what lash is I am unaware of that term. Also when you say you let go of the gauge is that when you are actually making the adjustment with the gauge in place? That’s how I have been doing it. Firmly holding the screwdriver while tightening the nut. And then rechecking. That brings me to another question. How tight do you tighten the nut? Tom, I have read several posts on here and also Pelicans procedure and I am confident I am on the appropriate cylinder. Thanks for the tip on the shim I will keep an eye on them. You are both right this is madding blind folded brain surgery.
That is exactly the information I was looking for. Vandit could you please explain what lash is I am unaware of that term. Also when you say you let go of the gauge is that when you are actually making the adjustment with the gauge in place? That’s how I have been doing it. Firmly holding the screwdriver while tightening the nut. And then rechecking. That brings me to another question. How tight do you tighten the nut? Tom, I have read several posts on here and also Pelicans procedure and I am confident I am on the appropriate cylinder. Thanks for the tip on the shim I will keep an eye on them. You are both right this is madding blind folded brain surgery.
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03-27-2012, 08:43 PM
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As far as the back side method at this point I want to get a handle on the traditional method. I have my car up on jack stands and with my body under the car with my back propped up I can get a pretty good look at each valve. Especially with my cheaters on. 
03-27-2012, 09:29 PM
#9
I found that a good technique for me is,
1) test the "teeter totter" (rocker) to make sure I'm on the right cylinder. It also gives me a good starting feel as to whether the valve is obviously loose (or tight, although that's not quite as easy to feel).
2) Use the feeler gauge. if it's an exhaust valve and easy to get to/see, I might just use the gauge (if I can get it into the gap). If it's too tight, or if I feel like I've bent the blade and am not getting an accurate sense of what's going on, I usually go to step 3.
3) Use the "zero and back-off" method with the VAS (Valve Adjustment Screwdriver). I loosen the nut, tighten the screw down until it just bottoms out and prevents the rocker arm from moving (this is an acquired feel and it takes a few cylinders to really get a grasp on). Then back the screw off, using the VAS' "protractor" to get the right angle. Tighten the nut back down, and then recheck the clearance with the gauge (step 2).
1) test the "teeter totter" (rocker) to make sure I'm on the right cylinder. It also gives me a good starting feel as to whether the valve is obviously loose (or tight, although that's not quite as easy to feel).
2) Use the feeler gauge. if it's an exhaust valve and easy to get to/see, I might just use the gauge (if I can get it into the gap). If it's too tight, or if I feel like I've bent the blade and am not getting an accurate sense of what's going on, I usually go to step 3.
3) Use the "zero and back-off" method with the VAS (Valve Adjustment Screwdriver). I loosen the nut, tighten the screw down until it just bottoms out and prevents the rocker arm from moving (this is an acquired feel and it takes a few cylinders to really get a grasp on). Then back the screw off, using the VAS' "protractor" to get the right angle. Tighten the nut back down, and then recheck the clearance with the gauge (step 2).
03-27-2012, 10:37 PM
#10
Rennlist Member
Guys,
That is exactly the information I was looking for. Vandit could you please explain what lash is I am unaware of that term. Also when you say you let go of the gauge is that when you are actually making the adjustment with the gauge in place? That’s how I have been doing it. Firmly holding the screwdriver while tightening the nut. And then rechecking. That brings me to another question. How tight do you tighten the nut? Tom, I have read several posts on here and also Pelicans procedure and I am confident I am on the appropriate cylinder. Thanks for the tip on the shim I will keep an eye on them. You are both right this is madding blind folded brain surgery.
That is exactly the information I was looking for. Vandit could you please explain what lash is I am unaware of that term. Also when you say you let go of the gauge is that when you are actually making the adjustment with the gauge in place? That’s how I have been doing it. Firmly holding the screwdriver while tightening the nut. And then rechecking. That brings me to another question. How tight do you tighten the nut? Tom, I have read several posts on here and also Pelicans procedure and I am confident I am on the appropriate cylinder. Thanks for the tip on the shim I will keep an eye on them. You are both right this is madding blind folded brain surgery.
03-27-2012, 11:54 PM
#12
Valve lash is the mecahnical gap between the cam and the valve.
The traditional way is actually pretty easy once you get the hang of it.
No I tend to let go of the guage just before making an adjustment, and then I am sliding it around while turning the screw in and back out and back in until it feels just right. Let go of the guage, hang onto the screw driver tighten the nut, check with the gauge again to make sure it didn't tighten up on you.
Oh yeah, that is kind of a given but there is a special feeler guage tool for adjusting Porsches. You cannot get down there with anything else.
I am not sure what you mean how to tighten the nut, what tool? A deep off set box, and just grab on the screw driver and snug it. I am kind of a perfectionist so I go back and do a final torque with a torque wrench, and just run back through and check lash on last time before buttoning up.
I do the teeter-totter too. It breaks the little oil film suction and give you a reference (after you "get it").
And the feeler guage part itself gets beat up so its good to have a stock pile of them.
The traditional way is actually pretty easy once you get the hang of it.
No I tend to let go of the guage just before making an adjustment, and then I am sliding it around while turning the screw in and back out and back in until it feels just right. Let go of the guage, hang onto the screw driver tighten the nut, check with the gauge again to make sure it didn't tighten up on you.
Oh yeah, that is kind of a given but there is a special feeler guage tool for adjusting Porsches. You cannot get down there with anything else.
I am not sure what you mean how to tighten the nut, what tool? A deep off set box, and just grab on the screw driver and snug it. I am kind of a perfectionist so I go back and do a final torque with a torque wrench, and just run back through and check lash on last time before buttoning up.
I do the teeter-totter too. It breaks the little oil film suction and give you a reference (after you "get it").
And the feeler guage part itself gets beat up so its good to have a stock pile of them.
Last edited by Makmov; 03-28-2012 at 12:13 AM.
03-28-2012, 12:16 AM
#13
I found that a good technique for me is,
1) test the "teeter totter" (rocker) to make sure I'm on the right cylinder. It also gives me a good starting feel as to whether the valve is obviously loose (or tight, although that's not quite as easy to feel).
2) Use the feeler gauge. if it's an exhaust valve and easy to get to/see, I might just use the gauge (if I can get it into the gap). If it's too tight, or if I feel like I've bent the blade and am not getting an accurate sense of what's going on, I usually go to step 3.
3) Use the "zero and back-off" method with the VAS (Valve Adjustment Screwdriver). I loosen the nut, tighten the screw down until it just bottoms out and prevents the rocker arm from moving (this is an acquired feel and it takes a few cylinders to really get a grasp on). Then back the screw off, using the VAS' "protractor" to get the right angle. Tighten the nut back down, and then recheck the clearance with the gauge (step 2).
1) test the "teeter totter" (rocker) to make sure I'm on the right cylinder. It also gives me a good starting feel as to whether the valve is obviously loose (or tight, although that's not quite as easy to feel).
2) Use the feeler gauge. if it's an exhaust valve and easy to get to/see, I might just use the gauge (if I can get it into the gap). If it's too tight, or if I feel like I've bent the blade and am not getting an accurate sense of what's going on, I usually go to step 3.
3) Use the "zero and back-off" method with the VAS (Valve Adjustment Screwdriver). I loosen the nut, tighten the screw down until it just bottoms out and prevents the rocker arm from moving (this is an acquired feel and it takes a few cylinders to really get a grasp on). Then back the screw off, using the VAS' "protractor" to get the right angle. Tighten the nut back down, and then recheck the clearance with the gauge (step 2).
Pretty much the same thing I do.
03-28-2012, 01:06 AM
#14
Rennlist Member
[QUOTE=stinkydog;9397621
3) Use the "zero and back-off" method with the VAS (Valve Adjustment Screwdriver). I loosen the nut, tighten the screw down until it just bottoms out and prevents the rocker arm from moving (this is an acquired feel and it takes a few cylinders to really get a grasp on). Then back the screw off, using the VAS' "protractor" to get the right angle. [/QUOTE].
BTW, I have only a few of my screwdrivers left if anyone wants one to augment the procedure
You can see them here, along with a video of valve adjustment tips.
3) Use the "zero and back-off" method with the VAS (Valve Adjustment Screwdriver). I loosen the nut, tighten the screw down until it just bottoms out and prevents the rocker arm from moving (this is an acquired feel and it takes a few cylinders to really get a grasp on). Then back the screw off, using the VAS' "protractor" to get the right angle. [/QUOTE].
BTW, I have only a few of my screwdrivers left if anyone wants one to augment the procedure
You can see them here, along with a video of valve adjustment tips.
03-28-2012, 07:23 AM
#15
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Well to add to the post, I have just done mine for the first time as mentioned elsewhere, I had the same problem as you. In my case when I put it all back together I had a noisy tappet on the upper right bank, which was a mystery. I had done it carefully and been around it twice. When I took it apart again I found intake 5 & 6 to be clearly too loose, which they weren't when I did it.
I think the solution is as Makmov stated - let go of the feeler gauge as you tighten up the screw, then slacken off to achieve a good gap with drag. I did this second time around and now it is fine. Its the hardest engine I've ever worked on!
I think the solution is as Makmov stated - let go of the feeler gauge as you tighten up the screw, then slacken off to achieve a good gap with drag. I did this second time around and now it is fine. Its the hardest engine I've ever worked on!