noob valve adjusting on 1978 280z

[argniest]

This is going to be long, but I know you guys/gals like data, so I am trying to preempt most questions. :cool:Well this winter I have been busy. I removed fuel sending unit, which showed me I had 1/2" of rust in laying some places on bottom of gas tank. And the fuel filter was filled up with a lot of rust too (I cut it open of course -and most if it got stuck right to a magnet I put near the pile of rust). So I figured out how to remove the tank (it got cleaned and restored by a pro who does that kind of stuff - washed out, boiled out, acid, and then 2 coats sealer and now its awesome), all the hoses, the fuel pump replaced (put on new original connectors for the new bosch fuel pump), damper assembly cleaned, fuel filter repalced, fuel rail removed and cleaned with carb cleaner, removed and replaced fuel injectors with new good ones (and all the orings too), changed fuel pressure regulator. I replace with all new parts, and all new fuel injection hoses and/or fuel hoses where needed, i cleaned out the long metal fuel rails under car with carb cleaner too, it helped somewhat. Also new air filter, new boots on the AFM both sides....

Oh yes, also changed oil with castrol 10W40, and put in the datsun/nissan big blue oil filter, and it has new NGK wires, NGK B6ES-11 plugs (gapped to .40)

Of course, the car runs better now, better than ever before (too long to explain) but its still only getting 10IN of vacuum. :-( at idle.

Both myself and some local mechanics, used carb cleaner around injectors and intake manifold, and nothing changed. We were thinking maybeI foo-barred some of the orings in injectors, but the engine did not budge one bit with any carb cleaner around intake manifold, or injectors. So it just seems to confirm even more, I dont have any foo-barred orings or intake leaks. I have new quick disconnect electrical connections for the new injectors, just havent had time to install them yet.

I found a local garage with a smoke machine, and no intake leaks were seen anywhere (and they had an oscilliscope/computer system they clamped onto the main ignition/coil wire). They also said secondary ignition system was looking good on the oscilliscope, firing pattern and burn time looking good/normal. I myself found many little cracked vacuum/pcv hoses and replaced all of them over past month while doing all this other work.

I cleaned all electrical connections and sensor connections in the engine area, cleaned grounding points in engine compatment where all the ground wires connect to, cleaned fuse box, replaced all fuses. Oh yeah replaced PCV valve, replaced thermotime sensor, replaced water temp sensor, AFM (air temp sensor was bad), replaced thermostat (it was running too cold and now its hot like it should be). I installed a new clear see thru G3 fuel filter after gas tank, after installing new tank back on car. I have a fuel pressure guage currently connected after fuel filter in engine compartment. So I can check it when needed.

My fuel pressure looks good when starting up, idling, and revving engine. Seems normal to me. Right around 36 psi.

I probably left some stuff out. But after all this work, the engine is running better then it ever had before, however, I really feel its holding back. I still smell some exhaust even with downward tip extenders (I think those reallllllllly helped a whole lot and only cost 10$)...And lets see, Im getting 7 to 8 mpg in town driving , yes really that bad, and my AFR's from the innovate meter are showing my idling at very lean conditions like 18 AFR or a little higher when sitting at stop sign, and WOT is 10.1 to 10.3, and crusing is around 12.5 average, sometimes almost 13 if I am going in a straight line and barely touching the gas pedal. I drove for 44 minutes and recorded all the data on the AFR meter and played it back on my PC. Several times now.

The local mechanics checked timing(and changed it as much as they say they could-because of the 10IN of vacuum the engine was only producing), they also played around with the idle adj screw and AFM bypass screw a little bit.

The also said distributor cap looked good and clean inside, and the distributor itself (what you can see by popping the top off anyway, basically looked OK - but they suggested a removal/inspection/and possible replacement of its 'guts', if needed)

After all this information I gave them, and the tests they did, they say I need valve adjustment. I have heard that before earlier in this project, but I have wanted to restore car to as much new stuff as I could....and also do as much of it myself. So I have learned a lot over the winter time, and thanks to many people on here to encourge me to do all this stuff.

However now to the meat of the meal, adjusting valves scares me somewhat that I could royally foo-bad something. I will be careful of course but still....So I was wondering if someone can offer some tips faq watchout problems etc. I saw bits and pieces of information about valve adjustment, but it seemed like they were for older z cars. Dont know how much it applies to my 1978. I have read about doing it hot and cold, and I would plan on doing it cold the first time. And I suppose first of all, I just need to remove rocker cover, and just inspect them in the first place and see whats what. And what their clearances are now.

!Oh yeah!, I learned how to do compression tests (was about 150 psi on average across all cylinders), but I did it with cold engine and didnt open the throttle (didnt know about it then, and still honestly dont know how to do that exactly), so I read on this site, that doing the tests warm, and opening throttle could add anywhere from 5 to 20 psi. So my compression could even be higher 155 160 170?

I also learned how to do leak down tests, on average it was 15 to 19% (mostly towards the 19% side) and one cylinder I could only get down to 23%, which all that seems OK to me from what I have been reading. According to the guage up to 40% is in the green, of course I dont really beleive you want to be around 40%, around 20% seems a lot better to me. And I was told that 15% is about normal for any average new(er) car. Ohhh I am sure I left some things out. And I realize just beacuse I replaced all this stuff doesnt mean its all working. But I am gonig to choose to believe it is all working for now. It really seems that if I have some valves that are tired and not set correctly, that my gas mileage will suffer, could smell wierd exhaust problems because of incomplete combustion, and not have the power I believe the car is missing right now. So I am reallly hoping a valve job can bring it back to even have more power and fun!

Edited April 15, 2011 by argniest

[d240zx2]

Adjusting the valves is one of the simpler things you can do. Verify the factory specified clearances for intake and exhaust valves, have the appropriate feeler gauges on hand, 17mm & 14mm open-end wrenches, remove the plugs and valve cover, place car in neutral. Use your crank pulley bolt w/27mm socket to rotate the engine to measure the clearance between the cam and lash pads. Adjust to specs as required. You'll be done in just a few minutes.

[ZCurves]

Wow, looks like you have been very busy! I am thinking that there HAS to be a vacuum leak somewhere. When you did the smoke test, did they just smoke it or did they add a florescent dye to the smoke and check the underside of the Intake. It is hard to see with the heat shield and everything. The florescence will really pop under the 'special' light/goggles. Did you remove the vacuum line going to the AC control valves BEFORE testing? Those valves sometimes will seize and result in a 'open' condition. Are all of the larger rubber hoses (e.g. Brake booster, Aux Air, PCV, etc) nice and snug?? Just asking.

The valve adjustment is no big deal, definitely something you should do. Do you have an FSM for the '78? I have an one in .PDF that I cleaned and added links to the subject areas (to reduce scrolling), PM me and I'll send you a copy.

[argniest]

Yup, have been busy since last november, thanks to everyone on here too :-) who gave me confidence and great information of things to do. I know it may seem I am throwing parts at the problem. But my plan is to just make everything that I can, renewed. And if I have to get into finer testing parameters, I would rather do it with new equipment. I did test (or have tested) some of the parts that were replaced, and found them to be bad. I also did the coveted fog machine test inside the cabin, which helped teach me some things about venting holes, and other things to 'seal up' to reduce any exhaust coming into the car. I also treated some minor rust issues on some places under the car while the tank was off, like the big metal plate that holds the bumper onto the car. I used the 4 step eastwood chemical/paint process for that, and for the outside of the gas tank, so my tank is chassis black (satin) and looking like new or better. Ooooooh well....

Yeah I cant believe I am getting 10IN of vacuum for no reason :-O....it does make sense to me, with what I understand about the engine now, that having the valves adjusted could really help a lot. But first I just need to open rocker cover, and just measure them and see where they are at. And who knows what else I will find. Hopefully everything will be in good order, and just need some minor adjustments. Actually I did have the rocker cover off once before at a local mechanic, wayyyy long time ago in this process. We didnt see anything out of place. But didnt get into any details, he just did a quick measurement of a few things.

Edited April 15, 2011 by argniest

[argniest]

1. Yup, I know about rotating the crankshaft pulley :-) I had to crawl under the car a lot, when I was doing the leak down testing, to get all pistons into an TDC position. Well at least close enough to TDC to give me good readings. I realize that maybe it wasnt at exact TDC, but it was very close. I found a 27mm socket to use. So that will be easy for me to do during a valve inspection.

2. No, they didnt add dye. I will call them and ask if they do that. I have those goggles and lights that I used for a different vehicle. Thats a good idea thanks!

3. Did you remove the vacuum line going to the AC control valves BEFORE testing? Those valves sometimes will seize and result in a 'open' condition.

I dont know about this, where is it? Can yuo tell me a little more about this.

Also, if I didnt mention it, I also dont have heat coming out of the vents. No matter what setting I put the controls in the car on. The air isnt stone cold either, but I can detect a tiny amount of warmth in it. I mean a very little.

I have been stuyding about that system a little bit, but its somewhat of a lower priroty right now. I have an IR temperature meter, and I checked the hoses (the short red one, and the black one) that run through the firewall of the car, and the temps are like 150 to 160 degrees in those hoses. (also, I recently replaced the tstat and gasket, and that made my engine temp gauge go back up to the middle range, and the temperatures are like 180 to 185 degrees around where the top radiator hose goes into radiator, so I believe that part os the car is now working correctly). That tells me I am getting heat into the heater core??? but something else is amiss with something inside the cars heating components. Thats a whole area I dont know much about yet....But I also believe a low engine vacuum condition, could be the culprit in the heater, because I thought it uses vacuum to operate some switch/diaphram to let heat flow. So maybe the heater isnt working, just because vacuum of 10IN isnt enough to allow it to operate properly.

I cannot say if it ever operated at all or normally. I guess I just cant remember everything :-) The car sat for last few months of 2008, was being repaired in 2009 and 2010 by my cousin who restores cars. I have many other posts on here that explain all the other work that was done on the mechanical stuff on the car. In between some of that work, he asked me to test drive it. So, its almost like new now from a total car perspective. If a valve job would help bring the engine back to more normal operating parameters, that would be soooooooooooooooooooooooooooo awesome!

4. Are all of the larger rubber hoses (e.g. Brake booster, Aux Air, PCV, etc) nice and snug?? Just asking.

I would like to say I am 100% sure about all of those hoses, but you never know. I have tried to check every connection on the intake hoses. Doesnt mean I missed one or two. I will go back through and dbl-check them all this week, its gonna be raining a lot I guess. So I dont get to do any test drives anyway. That was another reason I wanted to find someone who had a smoke tester. They left it on there for 4 to 5 minutes maybe?, and none of us saw anything. It doesnt mean that wasnt a leak, but if there was, it had to be very minor...however, looking at the underside of car, and just in general, after using dye would be useful!

5. Do you have an FSM for the '78?

Yup I have the nissan 750 page long original FSM, and another really good one from clymer from 1979 that has great information and some procedures explained better for my brain anyway. And I have the electronic pdf files I got off the internet. And several of the great sites referenced from people here. I am always reading these materials all the time. In a quest to learn everything that I can about my car.

Edited April 15, 2011 by argniest

[ZCurves]

Also, if I didnt mention it, I also dont have heat coming out of the vents. No matter what setting I put the controls in the car on. The air isnt stone cold either, but I can detect a tiny amount of warmth in it. I mean a very little.

But I also believe a low engine vacuum condition, could be the culprit in the heater, because I thought it uses vacuum to operate some switch/diaphram to let heat flow. So maybe the heater isnt working, just because vacuum of 10IN isnt enough to allow it to operate properly.

That tells me a lot, I am really leaning toward it being from vacuum leaks at the Magnet Valves. When these are inoperable the Heating and AC will not function properly. These valves control the Fast Idle and the Mode Doors inside the dash. So although you performed needed maintenance on the Thermostat, the Mode doors are not opening to let the heat flow into the cabin - same would be true for the AC.

The AC/Heat controls in the dash need to have a vacuum to operate and that is supplied via the Vacuum Reservoir and the Magnet Valves. In your FSM, refer to pages AC-13, AC-36, AC-37

If a valve job would help bring the engine back to more normal operating parameters...[sNIP]

I think that you are mean Valve Adjustment. Valve Job is a different task and a much more drastic step.

I have to mention that from reading your previous posts that you are being too modest in regards to your Z Car knowledge. You have done quite a lot and I for one am very impressed.

Good Luck & Post Pics,

[FastWoman]

Hi Argneist,

It sounds like you're getting to the point where I was a while back. You've done a LOT of work and your engine still isn't right. Cozye got to a similar point, and we sort of worked through a common solution together. It turns out that our ECUs had drifted in their timing properties over the decades, and so we had to trick them about coolant temperature in order to correct their timing. You can read all about it in this very long and meandering thread:

http://www.classiczcars.com/forums/showthread.php?40234-Purs-like-a-kitten...&highlight=

Somewhere buried in there is my "yogurt cup test," whereby you remove the AFM, stuff a yogurt cup into the AFM/throttle boot, place a hose on the vacuum booster nipple, and blow on the hose with your mouth to "inflate" the entire intake system. A bit of air will leak out, but if the intake is tight, it won't be much. It's a very quick way to confirm that you've found all your vacuum leaks (rather than searching endlessly for a leak that might or might not be there). Once you've put the vacuum leak issue to bed, you can move on to other issues.

Anyway my engine wasn't running quite as badly as yours (judging from vacuum numbers -- mine being maybe 14 in Hg initially), but I was able to get my engine running quite well by adding resistance to the coolant temp sensor circuit (thereby correcting mixture). I now run with about 18.5 in Hg. Cold and warm running are quite good. I think I'm just a tad on the rich side, but better rich than lean. (I can adjust the mix leaner with the turn of a screw if I want.) My engine almost always starts in less than a second (1 revolution?) and runs strongly. The only exception is if it's been running and sits for about 20 min, during which time it becomes heat soaked and might take a few revolutions to start. Mileage is about 19 or 20 combined, and more towards the upper 20's on the highway. The magic that made all this happen is a little resistor in series with my coolant temp sensor. :-)

Anyway, study the thread I linked, and you'll see how Cozye and I systematically went through all this stuff. (He achieved similar results, BTW.)

Oh, and don't worry about the valve adjustment. It's a very easy and strangely satisfying undertaking. You'll be working on the most beautiful part of the engine, IMO. Just don't get your hopes up that it will awaken the beast in your engine. It probably won't make a huge difference, but it definitely needs doing from time to time. Enjoy!

Edited April 15, 2011 by FastWoman

[argniest]

Thanks Andrew for the compliment (and do you have a 1978 280z also, in 510 blue? it looks like you might). Yes, I did mean a valve adjustment and not valve job :-)...I just corrected that hehe. Yup, I have done a whole lot of things to my Z car to make it as new as possible. I also have completely gutted the inside of the car and put it back together now, soundproofed it with some dynamat, fixed a door lock problem so I can unlock the door now, sealed some new plastic sheets in front doors to seal them off, and dynamat in some places. The car is queiter because of all this, I fixed some small surface rust issues in a few places in the car, and other little stuff too. Put in a new electronic antenna back there. Installed a custom made 6 x 9 speaker box that looks like it belongs back there in the car, installed new 4" speakers in the side holes behind drivers head. The stereo sounds great, and its not even barely getting started. I spent months designing a very nice system for it. Just waiting to get engine running right, then I will move onto that someday hopefully sooner than later but who knows.

HA Its like the last 6 months just vanished. I have like four levels of tasks to do, I am basically done with level 1 and level 2 which are the more serious stuff, and am playing around in level 3 and 4 stuff I imagine for the next year. Tracking down some wierd things like non working side marker lights and no hazard lights.

Also, I am going to install a new backup light switch soon, its kind of leaking and also has a wire broken on it. Im getting way off the subject, sorry its hard to not talk about all this stuff I have done. I am proud of myself for being patient, reading and learning and DOING, and thankful for everyones help to get me to this point

WELLLLLLLLL ANYWAY

If this valve adjustment brings the car MORE power and life, and better gas mileage, I will be very happy! you cant even imagine! I need to study up on exactly how to do the procedure. I know its easy for anyone who has done something like this before, but staring down the gun barrel when you have never done anything like that before, its a little intimidating. And by gosh I dont want to do any harm. Only good! It is sounding like I shouldnt except a whole lot from adjusting valves. It would be nice if they were in spec, but that only leads to other problems. So it is what it is...somewhere there is a monster hiding and I wanna nuke it.

I also just read the new post right above here. Ohhhhhhh wow, that is very interesting about the yogurt cup test. I need to do that for sure like RIGHT AWAY this weekend. Its making me about MAD, wondering, hmmmmmmmm does my Z car have a vacuum leak or not. I want to get it behind me JUST LIKE YOU SAID. Even tho those mechanics and their smoke test machine didnt blow smoke out anywhere, I jsut cant seem to let go of the fact that maybe there is still a leak somewhere.

Also, I can somewhat understand what you are saying about the ECU drifting away from its specs, and you had to figure that out and how to compensate for it. I hope that is within my reach. I need to read your thread and see if that is something I can do too, something to do, if I need to do it. It could explain a lot. but I havent eliminated other variables yet like the stinking TVS. grrrrrrr too many things to do. But at least I have learned a lot this winter, and done a lot to make things better. And limit scope of the problems.

Edited April 15, 2011 by argniest

[argniest]

Just one other funny thing, is since I restarted it for the first time a few weeks ago after finally getting everything installed (it started first time BTW -after an ordeal with getting the fuel pump primed, all I did is remove gas cap - hehe) I have taken it on test drives. And almost everywhere I go, I catch people turning their heads, they talk to me at stop lights, want to race me, give me thumbs up, want to buy it, etc etc etc. I want to get it running so good, so bad !!!!!!!!!

Edited April 16, 2011 by argniest

[argniest]

Hi Argneist,

It sounds like you're getting to the point where I was a while back. You've done a LOT of work and your engine still isn't right. Cozye got to a similar point, and we sort of worked through a common solution together. It turns out that our ECUs had drifted in their timing properties over the decades, and so we had to trick them about coolant temperature in order to correct their timing. You can read all about it in this very long and meandering thread: http://www.classiczcars.com/forums/showthread.php?40234-Purs-like-a-kitten...&highlight=

WOW thats a lot of interesting information about the resistors etc. I just finshed browsing thru all 4 pages. Nice. Its good to know there are things like that to try out if needed. I am hoping I will get lucky and be up and running without crazy stuff like that :-) However, I will be doing the yogurt cup test just as soon as I can. That sounds brilliant!

I am pulling the rocker cover off in a few minutes because I cant wait until tomorrow...and found this great article too http://www.picturetrail.com/sfx/album/view/1803105 about doing the whole procedure. I need to go pickup a remote starter tomorrow and one of those crows feet wrench tips.

I was thinking I was going to be crawling under the car like before when I did the compression tests and leak down tests...to advance the crankshaft pulley with my 27mm socket. But the remote start will make it painless. nice! If I need to tweak position of crankshaft a tiny bit I can always get under there and do it manually like before. AND YES I WILL KEEP IT IN NUETRAL SO I DONT RUN IT THRU THE BACK OF THE GARAGE....

Edited April 16, 2011 by argniest

[Gary in NJ]

Valves are at the top of the engine, oil sits in the bottom of the pan. No need to drain the oil.

By the time you get to the last valve, you'll be an expert and will want to recheck them all.

[SteveJ]

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