Valve adjustment practice

[na2ub]

Years ago, I did my first valve adjustment and got them all way too loose, so I drove it the the mechanic and had him do it. It's now time to do it again, so I gave it another try. Much better this time, but a couple of them must still be too loose, as I can hear them tapping more than before the adjustment. I called the mechanic to check prices, and it was 6 hours @ $90 plus parts.

Bottom line ... looks like I am going to try again. I really would like to be able to do this properly myself. The first time, I tried for the "slight drag as you remove the feeler" which did not work for me. Recently I tried to tighten until the feeler was stuck, then back off ever so slightly, just enough so I could actually remove the feeler. I would love to just check and adjust any valves that are out of spec, but there is no way I can get the feeler in the gap to check. When I was doing them, I backed them off a couple turns and still sometimes had trouble getting the feeler in there. This might also be part of my problem, as I was not able to "double check" the gap after adjusting them.

Any other tips before I do it again? I don't think I will try the backside method.

[Ronnie's.930]

I much prefer the backside method - you haven't tried it? The only awkward thing about it is figuring out how to insert the feeler blades . . . once you figure this out the process is smooth sailing!

[scotricker]

Hey Doug,

Yes, try it again. Do you have that special feeler gauge with the little tips? If so, it works best for me by sliding it in there from the side. Not stuff it under with the end first, but scoop it in there from the side. That's my best tip.

If you can't get the gauge in there, they are probably too tight, and that makes them quiet. A little noise/ticking is OK, normal. Use a flashlight to be sure you are attempting to get the feeler under the swivel-bendy elephant foot. And first, before you even try to get the gauge in there, pull up/out on the rocker arm to be sure there IS a gap to check!

It took a few times for me to get the super secret feel, and then you know it's right.

Do it again, use new gaskets. Take your time.

[na2ub]

Thanks scot. Those are good tips. I am definitely trying it again, even if I have to do it two more times. Any day when I can make (save) $90 per hour is a good day for me! Any one know how much oil I would need to replace if I only drained the sump and left the tank full?

Also, since you mentioned pulling up on the rocker arm, can I wiggle the rockers up and down after the adjustment, to see if any seem to have too big / small of a clearance (compared to each other)?

[boyt911sc]

Doug,

Just did a valve gap adjustment/setting yesterday. Once you learned how to do the backside method, it would make you consider not to do the conventional method (elephant's foot) anymore. Both methods work and require different feeler gauge set-up. Even with the engine on the engine stand, using the conventional method requires more effort and concentration than the back side method. Use the method you feel comfortable.

Tony

[DG624]

And first, before you even try to get the gauge in there, pull up/out on the rocker arm to be sure there IS a gap to check! This is good to know. I did the same thing...too loose and it sounded loose. I had it readjusted for $400 but it still sounds like it is ticking some. I also did the backside method but did not see the advantage. Apparently all of my valves were tight before I tried to adjust them.

I was also told that tight is "not bad" or "is bad" or "can get worse" or "will not get tighter". Depending on who you talk to the valves may or or should not make noise. If I do this again I will definately make them tighter but like Doug said it is hard to check since I was unable to reinsert the guage with them tight so I loosened them to check. There is also a description of clearance in the engine compartment that is in conflict with .004" on one sticker and .004 +/- .002" on another in the engine compartment.

[billwagnon]

Wear a headlamp - it makes things much easier. Energizer has one for about $15.

When I adjust mine, I slide the gauge blade up until the gap is reached. You will feel the groove where the parts meet. Then work the gauge into the groove.

[DG624]

My problem was not just the tension (gap) but the tightening of the nut without changing the gap. The difference between too loose and too tight is very small. I guess the best way is to tighten with the feeler guage inserted to eliminate too tight.

[RoninLB]

maybe try keeping a short wide screw driver on the adjustment screw till your wrench it snug to maintain adjustment

then after snug you shouldn't need the screw driver anymore to tighten it up

not very very tight


use new gauge blades if you wrinkle the one you're using

[island911]

Originally Posted by DG624

[I]... There is also a description of clearance in the engine compartment that is in conflict with .004" on one sticker and .004 +/- .002" on another in the engine compartment.

Giving the tolerance is additional and VERY useful information.

IOW, feel free to use .002" or .003" gauge and have an easy time of it. You can double check with a no-go .005" but I expect that you will learn quickly ...get a feel for things. And not risk too loose.

[Christien]

6 hours?! Time to find a new mechanic. An honest one. My first valve adjustment took less than that and I had NO idea what I was doing. If you're paying him to learn he should a flat rate. If he's done it before, then he's full of crap at 6 hours. Having done it 4 or 5 times myself (and about to do it again next week) I've got it down to max 3 hours, including cleanup and changing the oil while I'm at it.

[Eagledriver]

It does take time to learn how to get the feeler blade in the gap. Make sure your are at TDC on the compression stroke for each cylinder you are checking (rotor pointed to the spark plug wire for the cylinder you are adjusting). I check with a .004 blade and if that's tight I check with a .003 blade. If the .003 blade goes in easily and the .004 blade is on the tight side, I'm good. If the .004 blade slips in loosly, then I tighten the adjustment. When I need to adjust one (because it checked too loose or too tight), I turn the adjuster in until the gap is "zero" and then back it off 30 degrees. 36 degrees is .004 inches. If I'm accurate with my eyeball protractor, this works 90 percent of the time. The trick is to get to zero clearance without actually pushing on the valve before backing off 30 degrees.

-Andy

[Canada Kev]

The tightening everything up and still maintaining proper gap can be a bit of a handful until you get your "system" down. For me, I hold the feeler in one hand while adjusting the screw with the other. When it is the correct tightness with I just rest the feeler handle on the side of my hand to keep it from falling and grab my box end wrench which is conveniently already hanging around the shaft of my screwdriver. With a little practice, it's pretty easy. Three hands work with two.

[JJ 911SC]

Originally Posted by boyt911sc

Doug,

Just did a valve gap adjustment/setting yesterday. Once you learned how to do the backside method, it would make you consider not to do the conventional method (elephant's foot) anymore. Both methods work and require different feeler gauge set-up. Even with the engine on the engine stand, using the conventional method requires more effort and concentration than the back side method. Use the method you feel comfortable.

Tony

I did my first one the normal way with the engine out and use the backside method as a double check. I was surprise at how many occurrence (about 4 out of 12) that I though I was good to go until I check it using the back side method.

[na2ub]

Maybe I will have to look into the backside method to check. Its been a while since I read about that. I will at least take the time to insert the guage back in the gap after adjusting. It just seemed so impossible before.

Thanks for all the tips. I am sure I will re-read this before the next attempt. By the way, my las attempt was 8 hours, although much of the time was looking for tools! I really need to organize. Ordered my new gasket kit and extra feeler blades from PP today. I guess I will just drain the sump, since I just put new oil in.

I also plan on putting the car up on stands, draining the sump, and removing the valve covers the night before. That way, the job is already part done, and I won't get frustrated and take shortcuts / make mistakes.

Originally Posted by island911

feel free to use .002" or .003" gauge and have an easy time of it. You can double check with a no-go .005" but I expect that you will learn quickly ...get a feel for things. And not risk too loose.

Although too loose is the noisy side of the misadjust, I thought too tight was the "burn your valves" side of the misadjust. I suppose if the spec is +/- .002 then thats okay, but haven't I heard that the gap can close over time?

[Eagledriver]

You don't have to drain any oil if you do one side at a time. Jack the car up on one side and the oil runs to the other side of the engine. In fact you can break the job up into two smaller jobs this way.

-Andy

[szyzygy]

$90 an hour sounds like a good deal

[na2ub]

To pay the mechanic 6 hours @ $90 / hour, I would have to work 3 days to earn that money .... and for what, so some wrench can charge me 3 days work for a 3 hour job? I think I am going to be like that scene from Tin Cup, and keep going at it until I get it myself.

[island911]

Originally Posted by na2ub

...
Although too loose is the noisy side of the misadjust, I thought too tight was the "burn your valves" side of the misadjust. I suppose if the spec is +/- .002 then thats okay, but haven't I heard that the gap can close over time?

The problems arise when the valve doesn't close all of the way (less than no gap in the valve-train). The exhaust valves especially need to close (seat) so that, after being bathed in flame, the valve heat can be transferred out to the much cooler head. Theoretically there could be no adjustment gap, except for the fact that the head and valve expand at different rates while the engine is warming up to getting flogged. ...if the valve has no gap to 'grow into' then it would grow into the combustion chamber and never seat . ..over heat "burn up" (usually split on an edge ...sometimes break, at the flair, off the stem)

Oh, and I never use the TDC mark on the crank. I simply watch the valves go 'off lobe' (adjusting off lobe, of course) ...reason being that the tolerance/precision grind on the cam is much tighter than anything that I'm adjusting there.

What I'm getting at is, people often get really wrapped up in getting things just right, but really, the air pressure in your tires is tighter precision work than the valves. (being that we don't say; fill the tires to 30psi +/- 15psi)

Oh, and I actually have gotten the feel of the the right gap by simply rocking the rocker with my fingers. This seems crazy to people, but really, most people can feel when they've pulled one or two twenties out of their pocket (.004 each) or feel the slightest imperfection when sanding body-work. ...Anyway, there are a lot of valves to adjust, wiggle them to guess the gap, just for fun.

[JJ 911SC]

Originally Posted by na2ub

To pay the mechanic 6 hours @ $90 / hour, I would have to work 3 days to earn that money .... and for what, so some wrench can charge me 3 days work for a 3 hour job? I think I am going to be like that scene from Tin Cup, and keep going at it until I get it myself.

That is why I got a lift and the car has not been in a shop since Fall of 2009.

It already paid for itself.