Valve Adjust Question

[Adelaide901]

After a lot of research I am going to attempt my first valve adjust this weekend. Just one question remains.

When tightening the retaining nut - how tight should it be? As tight as I can turn it?

I read in one thread that a newbie mistake is to over tighten. Is this true?

Also, how easy is it to hold the correct setting with the screw driver whilst tightening the retaining nut?

Thanks in advance

[kodioneill]

It's impossible to torque the nut. I tighten it down with a 6" snap on box wrench past "snug". It will take you many attempts don't get discouraged. You should have on hand several feeler gauges because you will ruin many of them. You have to hold the adjuster screw while tightening the nut.

[Canada Kev]

I found that when you tighten the nut that last little bit, regardless of how tightly you held the screw driver, with slippery oily hands the screw would turn a little bit. I just started backing off the screw that same amount before I tightened the nut so that when this happened I wouldn't have to swear at it. Except in the case that it doesn't turn the screw when snugging up the nut...

Good luck. It's not a difficult job, but it does require some patience. Take it slow and easy and you'll do fine.

[don gilbert]

After you have done a few valves, you will get a feel for it, and it goes faster on the last 9-10. I like to give the adjuster and stem a squirt of brake cleaner to get the oil film out of the way, keeps the blade from sticking. Highlight the 3 marks on your pully, pull plugs, and I dont back up, if you go to far even just a bit, go all the way around.

[Canada Kev]

I thought the general consensus was to NOT remove the plugs. Risk of getting a bit of carbon under the valve, mucking up measurements and all that.

[kidrock]

I guess the best way to describe the torque value on the adjustment retaining nut would be as snug as possible. You don't necessarily have to give yourself a hernia. Although there have been a couple of rare instances where the nut may back off, it is just that...a rare instance.

P.S.---I'm with the "don't remove spark plugs" group. There is a bit of a risk, and it's really not that difficult to turn the motor with the plugs in place.

[don gilbert]

You are probably right about the carbon, might not want to chance it on an older engine. its just easier. i away blow mine out first, and hope i dont have any carbon build up yet on my fresh top.

[rusnak]

You might try trimming the blade down a little to make it stiffer and less likely to bend. I use the valve adjusting screwdriver with the little pointers on it. Makes things go very quickly.

Before moving on to the next valve, grab the rocker and give it a tug and push, to check the clearance without the feeler in there. You should feel a very small amount of clearance.

[Gunter]

Originally Posted by Adelaide901

After a lot of research I am going to attempt my first valve adjust this weekend. Just one question remains.

When tightening the retaining nut - how tight should it be? As tight as I can turn it?

To make it real easy for a beginner, loosen the nut, back off the adjuster, insert the feeler, snug up the adjuster to the feeler and tighten the nut. .

I read in one thread that a newbie mistake is to over tighten. Is this true?

Make sure to use a box-end type wrench and keep it fully inserted on the nut, then tighten a little past snug; not too crazy. It's all in the wrist.

Also, how easy is it to hold the correct setting with the screw driver whilst tightening the retaining nut?

Some adjusters will turn when tightening the nut and some don't. I use a short stubby screwdriver. It holds the setting easy.

Thanks in advance

Take your time. Always turn the engine cw. Observe the 120 deg marks on the pulley. The engine will turn by the fan-nut if you squeeze the belt. If the A/C compressor is in the way, move it over the right fender with lines connected.
Clean the mating surfaces of the valve covers. I smear grease on both sides of the gaskets to prevent them sticking the next time.

[Peter Zimmermann]

Originally Posted by syzygy

I thought the general consensus was to NOT remove the plugs. Risk of getting a bit of carbon under the valve, mucking up measurements and all that.

BINGO! Absolutely correct. If you're going to replace the plugs, and want the engine to turn a little easier, put the engine on TDC for cylinder #1, adjust the intake and exhaust rocker clearance, remove the #1 plug, and then turn the engine to #6. Do not remove a spark plug unless you are already on TDC of that cylinder, and are finished with your adjustments.

Firing order: 1,6,2,4,3,5.

Always turn the engine clockwise, but be aware that some engines have a distributor that will turn counter-clockwise. Always loosen the distributor cap so you can see where the rotor is pointing, Z1 on the crank pulley is TDC (top dead center) for both cyl #1 and cyl #4.

[911pcars]

Once you adjust the valves "by-the-book" once or twice, you might realize there's a lot of wasted motion involved with this procedure. Maybe that's why some shops charge significant dollars for this fairly innocuous procedure.

Here's a cross sectional view of one of the 12 cam lobes in a 911 (generic lobe shown);


Notice the constant radius at the heel of the cam (base circle) where zero valve lift is created. Since camshafts rotate at 1/2 the speed of the crankshaft (e.g. 20º of crank rotation = 10º of cam rotation) realize that the piston of the cylinder to adjust does not have to be exactly at TDC nor does the rotor have to point exactly at an exact location for the valve to remain closed.

When adjusting the valve clearance on a cylinder, look at the other end of the rocker arm and observe where the rocker contacts the cam lobe. If the rocker contacts the heel or base circle area, pretty much opposite the nose of the cam, you can adjust the valve clearance. To save even more time, back bends and deep knee squats, remain on your back in the valve adj. position and bump the cam into position using a remote starter switch on the starter solenoid so the cam lobe on the next valve to adjust is in the closed position, then proceed. Repeat about 10 more times.

Buy your SO dinner with the time you saved. If instead, you judge your projects via beer consumption time, do something else, like replacing the air in your tires, before heading back to the easy chair and telling her the ordeal you went through.

MHO,
Sherwood

[Peter Zimmermann]

Originally Posted by 911pcars

Once you adjust the valves "by-the-book" once or twice, you might realize there's a lot of wasted motion involved with this procedure. Maybe that's why some shops charge significant dollars for this fairly innocuous procedure.

Here's a cross sectional view of one of the 12 cam lobes in a 911 (generic lobe shown);


Notice the constant radius at the heel of the cam (base circle) where zero valve lift is created. Since camshafts rotate at 1/2 the speed of the crankshaft (e.g. 20º of crank rotation = 10º of cam rotation) realize that the piston of the cylinder to adjust does not have to be exactly at TDC nor does the rotor have to point exactly at an exact location for the valve to remain closed.

When adjusting the valve clearance on a cylinder, look at the other end of the rocker arm and observe where the rocker contacts the cam lobe. If the rocker contacts the heel or base circle area, pretty much opposite the nose of the cam, you can adjust the valve clearance. To save even more time, back bends and deep knee squats, remain on your back in the valve adj. position and bump the cam into position using a remote starter switch on the starter solenoid so the cam lobe on the next valve to adjust is in the closed position, then proceed. Repeat about 10 more times.

Buy your SO dinner with the time you saved. If instead, you judge your projects via beer consumption time, do something else, like replacing the air in your tires, before heading back to the easy chair and telling her the ordeal you went through.

MHO,
Sherwood

Gee. Boy, do I feel dumb. I did my first 911 valve adjustment in 1968. My work was checked by my two bosses, both trained by the Porsche factory. I got an "A". About 40-years later, and so many valve adjustments that it would be impossible to count, I now find out that I could have been doing it the "easy" way all that time. Boy, am I dumb.

[911pcars]

Originally Posted by Peter Zimmermann

Gee. Boy, do I feel dumb. I did my first 911 valve adjustment in 1968. My work was checked by my two bosses, both trained by the Porsche factory. I got an "A". About 40-years later, and so many valve adjustments that it would be impossible to count, I now find out that I could have been doing it the "easy" way all that time. Boy, am I dumb.

Pete,
I noticed a touch of sarcasm in your response. No diss intended in my response to the traditional method. BTW, also in '68, I performed my first rocker-less valve adjustment on a DOHC inline 6 Jag., and was taught by a MB-trained German tech and former WWII tank mechanic (also stationed in Russia). The Jag isn't remotely related to a 911 except for the valves, cams, pistons, crank, etc., but each int. and exh. cam requires R&R to adjust the valve clearance. There's more than one way to skin a cat. YMMV.

It was, as I signed off, merely MHO.

Sherwood

[T77911S]

sherwood,
i started to do mine this way once, but was not sure if this could cause inconsistencies in the adjustment. have you ever checked the clearance with the piston at TDC, then rotated the crank until the rocker was on another part of the base circle to see if the adjustment was the same? not putting down your suggestion, this was the concern i had when i started to do it the way you just said, plus i started to get confused on what was done and not done, so i went back to the traditional way.

for the OP. i never loosen the nut all the way, and i dont leave the feeler in there when trying to adjust them. if it feels lose, i pull the feeler out, with the screwdriver on the adjuster and a little tension in the CW direction, i loosen the nut just a little. then i turn BOTH CW together. i base how far i turn the screwdriver based on the ANGLE of the slot. then i recheck. if it needs more, i repeat, always based on the angle of the adjuster and making small changes. maybe an 1/8th or a 1/16th of a turn. if the feeler is tight, i loosen the nut and the adjuster together, then try to keep the adjuster from turning as i tighten the nut. make all changes based on the angle of the slot on the adjuster, then recheck. i never completely loosen the nut.

[Gunter]

Adelaide said that it's his first time, so, no need to overload him with short-cuts.
Let him do it the simple way; he'll get more confidence with experience.
No need to rush this.
Getting the feeler in can be very frustrating resulting in broken blades.
That's why I recommend to just loosen the adjuster enough to insert the feeler the easy way for a novice.

I don't like to use the starter repeatedly when the engine can be turned easily by squeezing the belt and using the fan-nut.

Valve-adjust questions come up all the time and there is a ton of info available; including one bragger who can do it all in 45 Minutes without even lifting the car.

Adelaide: Take your time.
If you have the long 10 mm Allen, check the torque on the head studs while the covers are off.
Also, you can make sure that the rocker shafts are still in the correct position; they can come loose and wander.

[T77911S]

yes, take your time. plan on an all day adventure.

sqeeze the alt belt, right side, to help turn the crank, im lazy and dont want to remove plugs just to turn the crank. i put my thumb on the top of the pulley and push in on the side of the belt.

get some extra blades. i go thru several each time. i set mine so the feeler is very snug.

[Walt Fricke]

Well, I'm with Sherwood: there is no reason to fret about turning the crank counter clockwise, since all you need to get a good adjustment is to have the rocker on the wide base circle. Always rotating clockwise can be important when setting cam timing, where the tolerances are fairly small and you don't want to be pulling slack against a variable like the chain tensioner. But not for valve adjustment.

Fact is, several valves are going to be well and truely on the base circle at the same time, and thus can be adjusted without more crank movement. I had this figured out on my VW motors, and I seem to recall that two crank positions were all that were needed. 3 exhausts and one intake, then 1 exhaust and 3 intakes, or something like that. Trickier for a 911 with 2 more cylinders. Turning the crank is not a big deal when working on the intakes, but unless you have the engine out on a stand, it is for the exhausts when you don't have a helper. Me, if I can wiggle it I will adjust it when I am lying down under the engine.

But Dr. G is right - for Adelaide's first go, the by the book, clockwise firing order approach is a good one. Because you won't lose track of where you are, what you have done, and where to go next. Just set at TDC (Z1) or close to it, and wiggle the #1 intake and exhaust valves. If they won't wiggle, you are at TDC for #4 - and both #4 I and E will wiggle. You can either rotate the crank 360 degrees and start in on #1, or you can start on #4 and go from there. Don't realy need to pull the distributor cap and note where the rotor is for this.

And one should take comfort from the fact that if you are 0.001" off in your adjustment, nothing bad will happen. The valve lash opens as the engine heats up, so you won't have set things too tight, burn valve seats and valves, etc. And if a bit loose, at most a little more valve train noise.

In fact, it makes sense to slide the feeler in before loosening the nut, just to see where things are. If it is super loose, one might want to investigate some more - might there be carbon bits on the seat, could the cam be wearing, etc. Because the normal progression is for the valves to tighten up some due to seating surface wear.

One way to deal with broken feeler gauges, especially the short bladed ones held in by small screws to a handle, is to purchase long (12") single 0.004" feelers, and bend the end to a suitable not quite L shape. When it breaks or gets too deformed, cut off the bad part and make a new bend. I just purchased some from an outfit called Enco (~$2.00 each), but no doubt many of the machine tool suppliers sell these.

Walt Fricke

[Peter Zimmermann]

Consistency is paramount. Doing things the same every time is the key. Starting on Z1/cyl #1 every time is being consistent. Not taking the few seconds to turn the crank to cyl #1 from elsewhere is silly. The car is either on jack stands or a lift. Start with cyl #1, set the rocker clearance on I & E, and go to #6. Do it the same way every time. You read about guys who do a clutch, and forget to put the starter ring on the new pressure plate. You read about guys who do rear shocks and forget to tighten either the upper nuts or lower bolts. You read about guys who do a minor service, and start putting the oil in the engine - with the drain plug on the tool box. I can site hundreds of mistakes made by technicians that I've worked alongside, 99% were because of mental lapses. The best way to avoid those lapses is mental discipline. The best way to develop discipline is to be consistent. Don't try to re-invent the wheel, it's already been tried and it's a waste of time.

[T77911S]

i buy the feelers from the store, then i cut the 004 and make my own replcaement blades, usually because i am too lazy to order replacements, plus it may be cheaper....anybody need a bunch of feelers, other than 004?

forgetting which ones i had done was why i went back to the firing order.

if i acnt get the feeler in, i will first wiggle the rocker to make sure it is on the back side or i am not on the wrong one.

when you get done, rotate the crank several times and go back and check them all again

[lindy 911]

One note about the feeler gauge; there is a learned feel for the correct setting of the valve clearance using a feeler gauge. When the gap is right you will feel a smooth drag when you slide the gauge back and forth in the gap. I did all my valves and my feeler gauge still looks new but I don't try to make it fit in the gap after the screw is adjusted.

Instead, I loosen the nut, loosen the screw, insert the gauge, adjust the screw, tighten the nut and then move the gauge and feel for the appropriate amount of drag. If it feels good I remove the gauge and move to the next valve. If it's too tight or too loose I start over, but I always leave the gauge in place.

You can get a feel for what's right by over tightening the valve screw to feel "too tight" and loosen the valve screw to feel "too loose". One of the best ways to make this easier is to find a screw driver that fits the adjustment screw slot perfectly without any slop. That way you can tell if the screw is moving when you tighten the nut.

Also, when you tighten the nut it will stretch the screw, changing the gap. You can get the gap perfect and then tighten the nut and it will open up. A little practice and you will learn to over tighten the screw a little and then tighten the nut for a perfect setting.

I always use the "lobe away" method. If the cam lobe is pointing away from the rocker arm foot, adjust it.

Lindy