Datsun Roadster Forum-311s.org

Posted: **Mon Jul 11, 2016 11:49 am**

svwilbur wrote:Mike,

ok so you do it at TDC. wiki says TDC plus 1/4 turn of crank pully which I think is 1/8 turn of cam. wiki does that to make sure they are fully closed.
Right the U20 is something I have not done so 1/4 of a turn is good and follow JT's rec

only #1 has a TDC marker on crank pully, oh maybe #4 lines up there too?
They both line up there but not at the same time a full 360 degrees apart 1,3,4,2 firing order
but #2 and #3 don' so you just use relative position of rotor and cam lobe position?
Yes on R16 and I can tell pretty close where 180 degrees is on the pulley mark
you cant really see the valves. just the springs and rockers. rockers are loose at TDC.
Yes, I make sure they are loose
you say my pully is off some based on what/why? my rotor position or that at the TDC mark my pistons likes to move backwards sometimes when blowing air in for a leakdown test?
Based on your statement in this thread above, I guess you meant the advance for spark not the pulley marks were off.

looking at the cam lobes it appears that for about half the cam revolution the valve should be closed so setting the gap should work anywhere in there but the other valve is some number of degrees off from it, like 90-120 degrees? exhaust closes before intake does. so at TDC the exhaust valve is getting ready to open and intake just got closed in its cycle. but both should be fully closed I guess.
The physics says they need to be closed as the engine compresses the gas and the plug is firing do not overthink here

Not qualified to answer the rest
something wierd that I notice and dont understand (I dont have any experience or knowledge of valve movement/engineering ) when I do the leakdown tests and have the cylinders at TDC or a little after and I put pressure in the cylinder and increase pressure slowly often the air will leak out the intake valve until I get to 35-45 psi and then you hear a valve or something slap closed and psi comes up (leak is less) up to that point the psi is down 15 or 20 psi and then it shuts and is only down 1 or 2 psi. there is no cylinder or cam lobe movement at that point. just a thud and the leak goes away. what causes that?

so it seems like the valve is not fully closed by the springs lifting them up?
maybe it is just something to do with blowing air in the cylinder. but all the cylinders do that usually if you start pressure low at 10 psi and increase it up. then at 30-45 psi it closes (you hear a thud in the engine) and psi jumps up in the cylinder, the leak goes away.

so do the valve springs not fully close the valves when the rockers and cams get to the loose position? is there some slop?

or what would cause this thud and leak/no leak symptom when I increase air pressure in a cylinder during a leakdown test?

or is that thud a result of maybe my valve lash adjustment is too small and the valve is not fully closing without the cylinder pressure? I tried adjusting cold and I think I am getting them a bit too tight. im trying for .006 and .008 like gregburrows uses but not sure if im getting them right all the time. I checked them hot and they increase to about 8 and 10. maybe less.

so maybe I am not loose enough? and that causes the thud when I get enough pressure in the cylinder to fully close the valve?

my rockers are loose when the lobes are up in the 10 and 2 or 11 and 3 oclock positions. you can wiggle them side to side. but maybe they still have downsard pressure on ths valve and spring?

I don't know. that thud is just another wierd thing I noticed and dont understand.

quite the learning experience.

Posted: **Mon Jul 11, 2016 3:05 pm**

Stacey, lets back up a little.

There is too much noise in this thread with references to timing marks, the crank pulley, rotor position. None of that matters.

If you are just trying to set the valve clearance, it is very straight forward. Move a lobe so that it is pointing directly away from the rocker face.

Technically, that will be up at about 11:30----but there is a significant rotational range where there is no difference because the cam lobe ramp has not yet started -- about 11-1 o'clock is fine.

In this position you need .006-7-8-.009" clearance when the engine is at full operating temp. The feeler gauge will be dragging as you pull it through, but you should be able to get it in the gap without huge effort. All you are doing is setting the free space between the two parts with the lobe pointed away.

As you get up past .010-.012" in space the rockers will start to get "ticky".

Whether you set it hot or cold doesn't matter, what matters is that the gap is present at full temp.

If you have to much gap, things will be noisey. Too little gap can burn a valve.

It is normal for the rocker to be able to rock left or right a little with .006" clearance, but not with a feeling gauge in place.

I'm not sure what you are going after at this point since the data from the leak down and compression tests looked decent, although there are some minor differences.

LMK if I can help further., jt

FYI, To me it sounds like the thud is just that in the position you are starting with, a valve is slightly open, the air pressure causes it to close and that rotates the valve train slightly.
You could remove all of this interaction by just removing all spark plugs and rocker arms. (just remember to number the arms 1-8 if you do)

Posted: **Mon Jul 11, 2016 4:23 pm**

jt, ok all that sounds about right to me. im understanding better.

basically I am just checking things out before chainging the timing chains and sprockets so that I have some assurance that my head does not need some work so that I don't need to pull my head.

but along that path I did the compression check and it looked ok, originally back in 1989 after the rebuild someone showed #4 way down. but now it seems fine.

the leakdown test cold seemed ok and then when I did it hot it was after a valve adjustment and #1 was ok hot but after it cooled a little while checking the other cylinders it was off quite a bit from where it was 30-45 minutes earlier without having run the engine in between testing or anything. it had me wondering. as leekdown went from 4% to 11%. it also lost compression. but I think that is all from having too tight a lash setting. changing the adjustment to be a bit more open started to bring it back into line. maybe there is some carbon stuck on the valve or something too.

im still learning this valve setting and effects on things.

im going to recheck and set valves using your method but cold and then run it a bit and check hot and rerun some compression and leakdown on a couple cylinders to check that #1 that I just had that anomaly with.

then if it all makes sense to me I will tear it all apart and do the chains and stuff.

I know i seem to be going in circles but odd stuff keeps happening. I prefer consistency and when something changes it makes me investigate.

thanks again.

Posted: **Mon Jul 11, 2016 4:31 pm**

jt you said hot the valves need to be .006-7-8-.009" clearance?
is that 6-7 intake and 8-9 exhaust or
between 6-9 for any and all of them, intake or exhaust?

book says .008 Intake and .012 Exhaust for hot.

should I just shoot for 6 or 7 cold, they expand about .002 when hot.
should exhaust be bigger?

Posted: **Mon Jul 11, 2016 5:33 pm**

svwilbur wrote:jt you said hot the valves need to be .006-7-8-.009" clearance?
is that 6-7 intake and 8-9 exhaust or
between 6-9 for any and all of them, intake or exhaust?

book says .008 Intake and .012 Exhaust for hot.

should I just shoot for 6 or 7 cold, they expand about .002 when hot.
should exhaust be bigger?

I found that the exhaust valves loosen up about .002 from cold to hot; however, the intake valves loosen up almost twice as much - .004.

Just my two cents.

Posted: **Mon Jul 11, 2016 7:53 pm**

.008 and .012 is fine. Sometimes you have to go a little tighter if the train is noisey, if you get below about .005-6" under operating temp conditions, that's where you may start to get into danger zone.

the absolute values of .008,9,10,11,12 are not particularly critical (unless to are trying to optimize individual cylinder timing in a race engine - which you are not) You can set them all at .010" cold, then listen with a long screw driver to each, and adjust the noisey ones.

You can try to set the intakes exactly at .008 and exhaust exactly at .012 if you prefer, but it won't make beans in terms of power output or performance. (Exhaust is given a little extra because the valve gets much hotter.)

What JB posted is about right on the OHC engine. The AL camstands expand, which increases the clearance slightly (don't think that the studs prevent that, remember steel is wonderfully elastic)-- but the valve stems and all the steel components expand too, which reduces the clearance. The exhaust stem expands more.

Because of all this interaction, HOT verification measurements are best, but don't think that they need to be exactly .008 & .012.

For the leakdown, unless you need it to run for some reason, Just take the plugs and rockers out since you need to anyway...jt

Posted: **Mon Jul 11, 2016 11:52 pm**

If you bump the starter with the key with the plugs installed (coil wire off or points/EI module disconnected... Ya dont want the engine firing!) it tends to rotate the engine to the next set. The lobes won't be straight up, but you will see which intake and exhaust valve is set for adjustment. With the plugs out it is too easy for the engine to spin, so it makes bumping the starter a bit more problematic. When I set my valves, I go tight enough that I have to wiggle the feeler to get it in, then check with the next size down to make sure it goes in easy, and the next size up can't go. So, I set intake for example at .006, check to see if a .005 will go (should) and if I want .007 (shouldn't). Again, a difference of .001 is nothing, but thats just what I do. Also, as you may have noticed they change significantly when you tighten them down, so adjust, lock them down, and check again. When you lock them down hold the adjuster nut with the 14mm. Too tight? Loosen the locker and adjust looser, hold and tighten and check again. You'll get good at this with practice!

Posted: **Tue Jul 12, 2016 6:07 am**

I could use a little touch of that OCD.

Sounds like your doing a great job.
Keith

Posted: **Tue Jul 12, 2016 8:45 am**

What Greg described above is pretty much how most of us would do it with a running engine I think.

Check final clearance with the engine HOT, since that is the only relevant measurement - but you can make minor adjustments hot or cold as long as they wind up within a couple thousandths of the manual and things are quiet. j

Posted: **Tue Jul 12, 2016 12:26 pm**

Thanks Greg, Joe and Jim,

I rechecked my valves yesterday using jt68's method of lobes up in 11-12 o'clock position and I think 5 were ok and 3 needed a slight adjustment.

I just used a wrench to turn the pully. my setup in the garage is too tight to try the wheel spin or starter tap.the problem is to get in the drivers door I have to roll the roadster forward 3 feet as it it up against some storage shelves. and then the nose sticks out past the garage door. so if it is jacked up it is a pain to try to start it for a compression or other test that needs the engine to move. if it is not jacked up then I can roll it forward to get in and turn the ignition but it is more painful then just using the wrench. I need a bigger garage. too many parts stored. and harley is parked behind roadster and 57 pickup next to roadster.

now the valve gaps, lash, whatever are all set to .006 intake and .008 exhaust for cold setting. I need to run it and see what they change to hot. I actually made note of them as gap of .006- .006 .006+ to indicate if it is a tight, normal or loose fit but in all cases .007, the next size up, does not fit in.

when I set them most get to a loose fit with a very little drag. some a little more drag but not tight. and the next size up will not fit at all. so .006 fits in and may or may not drag any and .007 will not go in at all. this is measured with it snugged up. seems like you have to have it not a tight fit or when you lock it down it always goes a bit tighter no matter how hard you hold the 14mm in position. and I do it with just loosening the 19 a very little bit to break it loose, adjust the 14mm, hold it and lock down the 19mm and check the fit.

I am surprized that it is so tight between the two. I would think .006 would fit loose or with a very light drag and that you could force fit .007 in but I can not seem to do that. same with .008 and .009. I guess if .006 was real loose .007 would fit. then I go tighter but if the .006 "fits" then .007 does not fit at all.

I am using flat feeler guages. maybe the bent type fit better.

I am working most of this week so pretty slow forward process on getting much done on the roadster. but she waits patiently for me.

I wish I had a small drive-on garage lift, my back does not like bending over working on the engine.

something like this https://www.eagleequip.com/product/PAD-6000W.html

Posted: **Tue Jul 12, 2016 1:16 pm**

svwilbur wrote:Thanks Greg, Joe and Jim,

+ I wish I had a small drive-on garage lift, my back does not like bending over working on the engine.

I put mine on Jack stand for working on the engine even valves or carbs.

something like this https://www.eagleequip.com/product/PAD-6000W.html

Posted: **Tue Jul 12, 2016 1:43 pm**

msampsel wrote:
+ I wish I had a small drive-on garage lift, my back does not like bending over working on the engine.

I put mine on Jack stand for working on the engine even valves or carbs.

something like this https://www.eagleequip.com/product/PAD-6000W.html

Yup I have some of those jack stands but I get to lazy to jack it up for that work. Especially if I still need to get access to the ignition as my drivers door is often on the wrong side of the garage and can not access it. I do use them when I am under the car.

Just a lift would be nicer. I have a low garage though especially if garage door is open. It would have to be a low lift.
But I would want it to be able to drive on when not in use and be used for lifting car with tires on the lift so you can work under it for exhaust, front end work, back end work or without the tires on it so you could also work on the tires, wheels, brakes etc.

I think I will see if anyone has a lift posting on here somewhere.

Posted: **Tue Jul 12, 2016 1:56 pm**

This one looks like it would fit my purpose:
http://kwik-lift.com/gallery.html
http://kwik-lift.com/information_video.html

talked about here:

http://www.311s.org/phpBB3/viewtopic.ph ... ft#p184096

This is interesting too as it takes less space and allows for better access around the car and to do repairs.
http://www.ezcarlift.com/index.html

I don't want to install 220 volt to my garage.
I don't have space for a 2 or 4 post lift as they require more room on the sides of the cars.
My 2 car garage is small since I have 2 foot storage shelves on both sides.

So both of those ramps fit those requirements for me.

Posted: **Fri May 28, 2021 6:07 am**

Hi all. Resurrecting this thread from yesteryear. Before jumping into the juicy plot, I wanted to say this thread was extremely helpful in understanding what goes into a valve job and how best to do it. Much appreciated!

I'm in a similar boat as svwilbur in that I'm attempting my first valve adjustment on my '68 2000 (and by first, I mean first ever on any car). This was purely preventive maintenance as the car was running well, outside of a high idle issue (but that's a book for another day). The car is bone stock and to my knowledge has not had any engine work. To level set things, I'm a bonafide noob/wannabe mechanic and appreciate your patience.

Ok, let's get to it. I got everything apart to do the job and jacked the rear passenger wheel to turn the motor. I followed the tech wiki method (not the alternative) and adjusted using cold settings others have found successful in various posts...namely .006 intake and .010 exhaust. For some reason I thought it was important to find TDC on each cylinder and check rotor position to confirm TDC before adjusting both valves while progressing through the firing order. My approach was: i) measure, ii) adjust (if needed), iii) tighten lock nut, iv) remeasure, and so on. If the gap moved after tightening, I'd repeat the process.

I wasn't exactly sure what the "feel" of the feeler gauge should be but tried to be consistent across each valve with a "medium" amount of drag. The next size up wouldn't go in without serious force and the next size down was just touching. Put it all back together and fired her up. Crazy loud ticking noise the moment the engine starts cranking. It started for half a second and I quickly shut it down fearing the worst.

Ok attempt #1 obviously didn't go so well. After finding this thread and reading all the great tips I decided to give it another go. This time I followed the â€œcam lobes upâ€ approach. I didnâ€™t pay attention to TDC, dizzy position, firing order or any particular cylinder. I simply rotated the engine until 1 or more lobes pointed up and adjusted the valve using the same method as before. I found some were out of adjustment and thought this would fix the issue. Started her up again only to hear the same tick-tick-ticking noise.

So what am I doing wrong? Seeking help from the group in hopes of getting out for a drive this holiday weekend. Thanks!

Posted: **Fri May 28, 2021 9:23 am**

Sounds like you're doing it all right. I'm guessing that what you're hearing is the few seconds before oil pressure comes up and stops the chain slop and rocker arm rattle. Run the engine for 20 seconds or so and it should quickly quiet down in the first few moments. (BTW, check into shimming the chain tensioner and inspecting the "evil L"...).

Do one set (one intake, one exhaust) at a time (they will be on different cylinders). The lobes won't be exactly straight up, but close. Your description of the "feel" was correct. Too much "lash" or having them set too loose is not as serious as going too tight... the valve must seat down or it can't transfer heat to the head and can become damaged, and no space or lash doesn't allow that. Stock settings as I recall are 8in and 12ex hot. Many of us go 6in 8ex COLD because they actually loosen with heat and will end up at 8 and 10 respectively (the 10ex being a little tighter than stock to reduce noise) once the engine warms up. Understand, so long as there's some space between the rocker and the cam you will be OK. The specification from the factory is as it is to allow for varying conditions such that the valve will ALWAYS be able to seat and transfer heat under all engine conditions, so there is no HUGE difference between 6 and 8 other than to potentially reduce valve noise by reducing "slop" if you will. If you were to go waaaay loose (like 16 and 18 hot) you might throw a lash pad at high rpm and they'll be very loud.
Hope this helps, feel free to continue to ask questions!

Datsun Roadster Forum-311s.org

Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20

Re: Valve adjusting problem on U20