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noob valve adjusting on 1978 280z


argniest

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If you want to adjust your valves, look on Blue's tech tips for Kammy's procedure. I found it rather easy to follow.

Yup, that is the site I was looking at, and they showed draining oil. I was a little baffled why that was part of the process, because as I understood what happened to oil, would not require draining it. But hey, I just thought I should ask before diving in.

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Sounds like great and satisfying progress. I enjoy reading your humble and ,yes, informative posts. I have a few suggestions regarding low vacuum as I had a couple of the same issues you have experienced.

"no heat"- I only had airflow from the console center vents. No floor or defrost. I found a cut in the line from the magnetic solenoid valves that supplied vacuum to the vacuum diaphragm valve, over the driver-side footwell. I had to remove the solenoid bracket to turn it upside down (passenger wheel well/engine bay) to find the cut. Not that I knew it (cut) was there, I just couldn't see every inch of tubing. Bingo! Flow control! But no heat. A little, for a few minutes as the thermostat opened but it quickly faded. More tracing of vacuum lines. Back to the mag solenoids. I rationalized (with the vac schematics) that I could troubleshoot the mode doors and vacuum valves under the dash by doing some temporary re-plumbing. Guess what? A cut that I missed. Right at the other mag valve. That leak kept the mode door in the "direct airflow over the a/c evaporator core" mode" vs. "direct the airflow over the heater core", which seems to be the default for the vacuum diaphragm valve above the passenger footwell. Hope that helps.

Secondly, check your oil fill cap on the top of the valve cover and the fitment of the dipstick. Easy for both, with the engine running, remove the dipstick. Put your thumb over the tube. If your vac gauge reading improves, the rubber on the dipstick isn't providing a good seal. Just removing the dipstick with engine running should change the sound of the engine. With your low vacuum, I wouldn't be surprised if it stalls. Same with the oil cap.

Kris

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Yeah Kammy is great guy! He actually shows a full tune up in that procedure. I believe the datsun maintenance interval instructions are to do a valve adjust with each oil change thus the grouping. I think he may also do timing too.

Not a Z but I like this guys go/no-go technique on a Honda S2000 using feelers: http://youtu.be/dwjbGPYGlyo

Edited by Blue
4th video
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well guys and gals here are some results. I removed valve cover tonight and got the feeler guages out. These are two things I have never done before. So I did this several times. Oh yeah I started out by using a remote starter switch which I also never used before. But I determine it turned the camshaft too fast, too far. SO I took that off and hooked up a big old wrench to the alternator "nut". And by turning the alternator "nut" I was able to spin the camshaft around in a lot smaller movements, which allowed me to move the cam lobe "the bunny ears" to be pointing straight up for each valve that I was testing.

Once I figured that out, I finally got comfortable (I think he he) to measure each of the valve spacing on all 12 valves. I made sure to pay attention to which valve went to which place intake or exhaust. You can tell of course, just by looking where it goes to, like the fuel injector is right there by intake manifold for each intake valve, and exhaust valves, well they are by the exhaust manifold which is lower than intake manifold basically.

I did it two times just to verify the numbers. I found that for instance, I could not stick in a .013, but the .012 could go in and out of that space with a little tension on it, but not a lot.

PS I have the 1978 280z 5 spd. Just as a reminder.

I did this with engine stone cold

So here are the numbers. I will number them from 1 to 12...starting at the front of the engine for cylinder #1, valve 1. (I)ntake valve and (E)xhaust valve.

1(E) - .012

2(I) - .007

3(I) - .008

4(E) - .012

5(I) - .008

6(E) - .012

7(E) - .011

8(I) - .007

9(E) - .011

10(I)- .007

11(I)- .007

12(E)-.012

Can anyone tell me if these numbers are OK, bad, really bad?? I dont know what tolerance the engine has to run with these numbers, and if they are bad enough to warrant causing my vacuum to be lowered a little, medicore, or a lot.

PS WilloughbyZ: That is all really great information, but I know nothing of any of that part of the car right now. As usual, everything like that I get into is brand new to me. I do have the FSM, and the clymer datsun manual from 1979 which has been really helpful for some things so far. So I can certainly look those things up. Do I have to take the dash out to see those things you are talking about.

What I am thinking about is this...could I just temporarily PLUG UP the vacuum lines that feed the HVAC system? I mean if there was a place outside the cabin of car (that is in the engine compartment somewhere) to cut the lines and plug them off in the engine compartment before they run into the car...so if there was a vacuum leak inside the car, at least I could more easily limit the scope of the problem. And then deal with it later. I can live without Heating and AC (I have factory AC that was working last year, but I havent even tried it yet this year, been too busy messing with a 100 other things as you can tell). But I am dying to find the source of this missing vacuum. Im at like 10 IN right now. And from what I remember, it was a fairly stable 10 IN, but not dead on 10IN the entire time. So I guess what I am saying is it wobbled a little bit from 10IN. ANd I dont know how rock solid a normal running Z car's vacuum pressure should be.

I know its way too low, and is making me about crazy now, to figure out what is going on and why. If you look at this point here, you will see the condition of my spark plugs just after a few hundred miles of test drives, and gonig to those few mechanic friends of mine.

Also I know the defrost worked before, but it seems like when I was playing with it during one of my two test drives this year after getting it started up again, that the defrosters did not come on. I can only say for sure the two vents in the center console were blowing air. I will verify next time I start it up, if any other vents are blowing air.

THANKS

Edited by argniest
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Well, your intake valves look a bit tight -- should be gapped to .010. The exhaust should be gapped to .012. Although the valves need a bit of adjustment, I don't see anything alarmingly out of align that would screw up your compression.

You shouldn't assume that low intake vacuum indicates a leak. Remember that your biggest vacuum leak is the throttle body, and it's supposed to be there. Engine vacuum is a reflection of the running efficiency of the engine.

You can test your HVAC vacuum tubing for leaks simply by removing the supply tube from the intake manifold (near the brake booster vacuum line) and sucking on it. You'll be able to feel whether it's tight. If you want to disconnect it for testing purposes, just leave the tube off, find a small piece of tubing the same size, put it on the nipple, and then plug the other end of the nipple with something like a golf tee.

Did you do the yogurt cup test yet?

Edited by FastWoman
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Well the numbers were done when stone cold, and arent they supposed to be .008 for intake and .010 for exhaust? So based on that, would these numbers be bad enough to cause running/vacuum problems in the engine? And no, I didnt do the yougurt cup test. I just really wanted to see how my valves looked, even if I didnt adjust them yet. So I had some idea if they could be the source of my low vacuum condition or not.

This will seem dumb, but since I currently have the rocker cover off, can I do the yogurt cup test with that off. I mean the engine is all interconnected, and I just am not sure if having it off would effect that test or not. Because some of the intake valves could be open...

Are you talking about pulling off the vac line #1 in my pics? And capping it off, then I could eliminate any possible leaks happening from the HVAC system, or should I say it would eliminate them from the equation. And limit down the scope of any vacuum leaks. Those guys smoke tester did not send any smoke out anywhere. But I also didnt look inside the cabin like under the dash where I suppose these lines are coming in.

And BTW, what is Vac line #2 in the picture. I am not sure what that is, but its running side by side with the other one.

post-23329-14150814536749_thumb.jpg

post-23329-14150814537363_thumb.jpg

Edited by argniest
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The rocker cover has to be installed to do my yogurt cup test. When you do this test, you'll be testing for tightness EVERYWHERE. This will include rocker cover, oil pan, oil filler cap, dipstick, intake manifold gasket, several closed intake valves, the piston rings and exhaust valves on the other side of one or two open intake valves, etc. The test won't pinpoint where you have a leak, but it will certainly confirm whether you have a leak that you need to track down.

Cold valve lash measurements aren't as reliable as hot measurements. Having said that, I suppose your exhaust gaps look a bit loose and intake gaps OK. Still needs adjusting, but nothing too far out of the ordinary. I wouldn't expect much improvement in the running condition of your engine from the adjustments. Your engine might run a tiny bit quieter -- less ticking. I doubt you'll gain much, if any, engine vacuum.

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If it aint broke dont fix it :). I definately DO NOT want to mess with the valves if I dont have to right now (for a noob, that is an uneccesary risk I do not wish to take if it isnt going to make that much of a difference). If adjusting them close to specs as I could get them isnt going to give me much improvment, then for now, I think I need to focus else where. I know, there are a 1000 things that could be causing this, and it seems we are saying I have eliminated the valves as the source of why I am at 10IN of vacuum? right?

The wierd thing about all of this, is that the engine sounds and feels better than ever, but I know its not right yet, and omg its getting like 7 to 8 mpg. And those AFR's numbers are not good either. Which I wouldnt expect them to be. And then the spark plugs, I posted a picture of them on my other thread about the AFM.....sigh! Can I beat my head against a rock now!!!!!!!!!!!!!!!!!!

Oh yeah, I do hear a little tapping under the rocker cover... so those exhaust valves being .002" off, could be the cause of it?

Thanks!!!!

Plug picture http://www.classiczcars.com/forums/showthread.php?41965-A-few-Questions-about-AFM&p=361195&viewfull=1#post361195

Edited by argniest
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Yeah, those exhaust valves could be part of the tapping. However, this engine will never sound as quiet as an engine with hydraulic lifters. It's going to tap very softly even when in perfect adjustment and perfect running condition. That's the nature of the beast. Nothing to worry about.

Personally I'd adjust the valves while you've got your tools out. Adjust a few valves while cold, just to get the hang of it. Then put the cover back on, run the engine until warm, and do the warm/hot adjustments. You won't break anything. Trust me that you're being much too fearful of this job.

But no, I don't think your valves are the source of the 10 in Hg vacuum, at least by themselves. They might make a small contribution, though. I suspect low vacuum in most engines has at least several causes.

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:stupid: Yup, I admit it, I am VERY fearful of actually touching the engine. Its one thing to replace external parts like fuel injectors, fuel tanks, and fuel hoses, but a whole other thing to mess with the parts of the engine itself. I WANT TO DO IT, but I dont want to mess anything up. like 1000x.

If those valve readings I took are not likely to cause much of my vacuum problem, I really want to wait and do it later. It seems there are too many other things that could be causing my problem. Now that we know where my valves are at.

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Honestly the solution to getting your engine right might be the systematic correction of a whole bunch of little problems like this one. Do this: Leave your sledge hammer in the tool box, along with the crow bar, pliers, and vice grips. Pull out some fixed hand wrenches (no crescent wrenches!) of the appropriate size, as shown in the slide show. (No, you don't NEED a crow's foot wrench. A regular hand wrench will do.) Now, with the tools you have in hand, I don't think you're strong enough to break or screw up anything!

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Honestly the solution to getting your engine right might be the systematic correction of a whole bunch of little problems like this one.
Yeah, I have to believe that is exactly what is happening, a whole bunch of little problems. and maybe bigger ones that I caused when I repalced FI's. Here is what you said:

"1) I pulled off the AFM and plugged the AFM-to-throttle boot with a yogurt cup. I pulled off the vacuum booster line to the brakes and attached a hose to blow through. I pressurized the intake with nothing but moderate lung power, held the pressure with my mouth, and got a feel for how long it took for the pressure to leak away. I then pulled the little HVAC vacuum control line (adjacent to the power brake vacuum line) and repeated the test."

I dont see how a yogurt cup would plug that space up? It seems like the hole is 2x thats size? Where is vacuum booster line? I just want to make sure I am doing the right thing here....And you are saying to take the AFM off the car. It seems with a yougurt cup in there, and then blowing into the intake system, isnt that just going to push the yogurt cup right out of there whenI start blowing into the hose I would attached. I know....more stupid questions. :(

I ATTACHED A PICTURE OF WHAT I THINK YOU ARE TALKING ABOUT, CAN YOU TAKE A LOOK AT THE PIC, THANKS!

post-23329-14150814538015_thumb.jpg

Edited by argniest
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