# TDC?



## rallyrob (Apr 14, 2011)

I have an 82 Datsun 200sx with the Z22E engine. Unfortunately it also has a blown head gasket.I am just about ready to bring it into the garage and start fixing it.Once it is in the garage is there and easy way to find TDC like a mark on the flywheel or crank pulley, or just pull a spark plug from #1 and wait until air rushes past my finger?


also what are the approximate dimensions of the wedge to jam the tensioner?

finally, are there some diagrams with head loosening and tightening steps?

thanks in advance.


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## smj999smj (Jan 1, 2006)

There are timing marks on the crank pulley and a timing pointer on the front cover. With the timing pointer and crank pulley marks lined up, the intake and the exhaust valve at #1 cylinder will both be closed if you are at TDC #1 cylinder; if not, you are likely at TDC #4, so turn the engine one more revolution. Nissan once put out a TSB giving the instructions on how to make the wedge, but, unfortunately, I do not have it. A tool was available made out of plastic that could be purchased, but they seem to be getting harder to find. Here's a pic of one:

handyforce.com - PRODUCTS-auto repair tools, hand tools, sockets, pliers, plastic cutter, bronze ball valve and fitting, air tools, power tools, screws, nut and bolt, auto parts, accessories

They were about 7 inches long, +/-, so you can probably make something out of wood based on the picture (you don't need the forked end like the plastic tool has).

Autozone.com has a free repair guides section that should have the R&R details and pics to help you out. All you need to do is register an e-mail address to access the data.


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## rallyrob (Apr 14, 2011)

While I have the engine apart I am wondering if I can simplify the mess of vacuum lines and solenoids under the hood.I have a couple of "what does this do and can i remove it" questions.For starters there are two solinoid/valve type things on the passenger side inner fender near the hood hinge.










then there are a couple of items on the center of the firewall.










So any idea what purpose they serve?
thanks in advance.


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## smj999smj (Jan 1, 2006)

In the lower pic, IIRC, the vacuum valves are part of the ignition spark control system. The black valve on the right is a vacuum sense switch used to help decide when to run the engine on just the primary, or intake side, ignition system or to run the engine using both the primary and secondary (or exhaust side) ignition systems. I believe the valve on the left is a vacuum switching valve and, if I'm not mistaken, controls the vacuum advance. (Keep in mind it's been a long time since I worked on an old 200SX and I'm dealing with my fading memory!) 

On the top pic, those are for the air conditioning system. The valve closest to the strut tower is an acceleration cut switch and the one closest to the firewall is called a "magnet valve."

My advice is to leave everything "as is" and eliminate nothing...or, "if it ain't broke, don't fix it!" If they didn't have a purpose, they wouldn't have installed it. Label all of your vacuum lines and replace any that are in bad shape (cracked, split, collapsed, etc.).


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## rallyrob (Apr 14, 2011)

I removed my AC system so I will remove the AC stuff.And not touch the other stuff.Thanks for the help.


just curious,but why doesn't the car run both ignitions all the time?


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## smj999smj (Jan 1, 2006)

It cuts out the exhaust side during heavy loads to reduce engine noise.


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## rallyrob (Apr 14, 2011)

what do you mean heavy loads?full throttle acceleration?driving up a hill?I thought it was during those times that the dual plugs would show its benefit.


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## smj999smj (Jan 1, 2006)

WOT and driving up a hill can both be "heavy load" conditions for an engine. The dual ignition system wasn't meant for more power but for cleaner emissions.


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## rallyrob (Apr 14, 2011)

could the system be tweaked with for more power?I advanced the ignition timing three degrees and it woke the car up.Could the vaccum sense thingy be bypassed so both ignitions ran all the time?


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## smj999smj (Jan 1, 2006)

Most Nissans with adjustable timing run better with 3-5 degrees of additional advance. As far as "tweaking" the dual-spark system, I wouldn't as you will likely experience detonation (which is what Nissan means by "engine noise" when describing their dual-ignition system).


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## rallyrob (Apr 14, 2011)

I was thinking it was more exhaust noise.Ok then I will not be messing with that stuff.


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## rallyrob (Apr 14, 2011)

HOLY CRAP this this is the most unbelievable pain in the butt Ive ever had the misfortune of working on.Ive spent two days taking this damned thing apart and the intake manifold and head are still firmly attached.All of the bolts holding the head on are off,the chain is held in place with the handle from a large wooden spoon.But the head wont come off,so I am removing the intake manifold to see if there is some bolts I might have missed.The intake manifold is held on by only two bolts but I have to remove the power steering pump to even see the bastids.Thankfully I won't be running the power steering anymore so that can be removed. It would have took less time to pull the engine and work on the damned thing on the floor.Would it have been so hard to make it so you can actually get to the bolts with a ratchet or at least SEE all of them NISSAN?!


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## rallyrob (Apr 14, 2011)

success! got the head off.I think it was leaking between the #1 hole and a coolant jacket.I say that because I didn't find and obvious tears or cracks in the headgasket.Only a very faint line from the coolant port...


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## rallyrob (Apr 14, 2011)

Unfortunately I accidentally broke one of the ports on the 3 port vacuum switch at the front of the intake manifold I'm not really having any luck finding a new one.What exactly does it do?


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## smj999smj (Jan 1, 2006)

What do the hoses attached to it go to? Can you post a picture?


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## rallyrob (Apr 14, 2011)

sure here is a pic.


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## smj999smj (Jan 1, 2006)

It's a thermal vacuum (or "TV") valve. Nissan part #14890-D8100. MSRP from Nissan @ $47.05, but you can get it for $34 at 1stAAANissanParts.com. You can also use the Nissan # to interchange it to an aftermarket valve from your local parts store. For example, it interchanges with Echlin #CRB 229091 which is available through NAPA @ $27.99.


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## rallyrob (Apr 14, 2011)

Ouch $30 for a little plastic valve.What does it control?


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## smj999smj (Jan 1, 2006)

It controls ported vacuum to a number of things, including the EGR valve, distributor vacuum advance, the vacuum switching valve and evaporative emissions canister. You may be able to find it cheaper if you search around. Try Rockauto.com or Autopartsgiant.com. Considering how old the car is, I'd be happy to pay $28 for a new one compared to trying to search for an old NAPZ engine in the junkyard that has a good one!


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## rallyrob (Apr 14, 2011)

why is the distributor vacuum advance ran through a thermal valve rather than just off normal manifold vacuum? I know why an EGR has to be run through a thermal vacuum switch,Just I am not really sure why the distributor should be run off a thermal vacuum valve.The EGR btw is not going back on the engine.


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## smj999smj (Jan 1, 2006)

Vacuum advance has to be run off of ported vacuum to work properly. I would leave the EGR valve on the engine unless there is something wrong with it; it's better for emissions and helps control combustion temperatures and eliminating it really won't give you any noticeable performance.


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## rallyrob (Apr 14, 2011)

the EGR system in my experience really doesn't do that much for emissions,As far as power goes if you remove the EGR and don't tweek the settings than yea no power increase.If you increase fuel just enough to compensate for the increase in available oxygen you will pick up some power. Fortunately with fuel injection the computer will adjust the fuel accordingly.Not to mention I seriously doubt it was even functioning by now.


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## smj999smj (Jan 1, 2006)

It reduces NOx emissions. May or may not be an issue depending on how your state does its emissions testing. In NJ. where I used to live, they test on a dyno. Here in VA, where I live now, they don't check emissions. Nissan EGR valves are pretty durable, so it may still be functional; a simple check with a vacuum pump will tell for sure. Carbon clogging the intake port is a bit more common. But, it's your car, so do what you want to do!


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## rallyrob (Apr 14, 2011)

the only smog testing in Idaho is in Boise,there they just put a sniffer in the exhaust at idle.

I will just eliminate that thermal valve by running the lines that went to it directly to manifold vacuum.Without the EGR there will be no worries about to much EGR at idle.

I'll just have to adjust settings a little bit,but hey thats what makes tuning fun.


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## smj999smj (Jan 1, 2006)

You can't run the vacuum advance off of direct manifold vacuum or you will have full advance at all times; vacuum advance needs to be "ported" vacuum. Eliminating the thermal valve also affects the vacuum switching valve, discussed earlier in regards to the spark control system. IMO, the best solution would be to replace the thermal valve. After 16 years as a Nissan technician, I learned to try not to "out-think" Japanese engineering; they knew what they're doing!


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## rallyrob (Apr 14, 2011)

full advance would only happen at idle and cruising at low throttle.All other times there would be less than full advance.vacuum goes down pretty quick when the throttle valve is opened.Besides idle and cruising at a low throttle are exactly the times you would want full advance.

if the vacuum switching valve is controlled by a thermo vacuum valve which is closed until the engine is up to operating temp, than that switching valve for the ignition only works when the engine is warmed up.Bypassing the TVV would make it still work,just also when the engine is cold.

I am just basing that on the fact that all of those systems use the same TVV.the TVV for EGR makes it so when the engine is cold the EGR isn't active because otherwise the engine would stall or run rough.So the TVV just makes it so the vacuum advance doesn't work until the engine is warmed up,same with EGR,and the same with the secondary ignition shutoff.So just don't boot the car when its cold and everything would be a fine.

unless somehow this one valve has multiple valves that open at operating temp and close at operating temp for the other ports.


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## smj999smj (Jan 1, 2006)

You do not want any advance at idle, which is why "ported" vacuum is used instead of direct manifold vacuum. Vacuum applied to the advance unit diaphragm should be applied gradually and in relation to the RPM of the engine. The thermal valve is designed to work in a specific temperature range and one of the lines of the valve is a vent line. Not only does it open an airway once the engine warms up, it also vents when the temperatures become excessive. But, if you want, go ahead and try what you want to do. Just don't throw away any parts and remember where all of the vacuum lines go in case you find out it was better off left the way it was!


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## rallyrob (Apr 14, 2011)

How did nissan set the plugs up to fire? do both plugs fire at once or do the intake plugs fire as normal then the exhaust plugs fire on the exhaust stroke?Ive heard it both ways on the internet.


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## smj999smj (Jan 1, 2006)

They fire simultaneously. There was a great article on the NAP-Z engine in the Dec. '79 issue of Popular Science magazine that you can access on the web. The article is titled "Return of the Hemi" (The Nap-Z is a hemi-head engine, if you weren't aware.) and begins on page 40. The link may put you on page 44, so you can just navigate to page 40 to get to the beginning of the article. Here's the link:

Popular Science - Google Books


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## rallyrob (Apr 14, 2011)

I had a friend who ran a 79 toyota in a demolition derby,it was as close to a hemi as you can get.center plug- 2 valves per cylinder- hemispherical head.So the car's number was "HEMI" all the dodge boys got all pissed saying it was a HEMI...either way it made 100 horse out of a 1.6L.

However I still have a question regarding the dual plugs,if they fire at the same time why does nissan recommend different plugs?the intake is BR6ES,and the exhaust is BR5ES.

also how much error compensation can the ecu provide? according to that article the engine takes in 19% EGR.there is room for more air/fuel. can the ecu provide 19% more fuel?


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## smj999smj (Jan 1, 2006)

I believe the exhaust side spark plug trails the intake side slightly, which would necessitate the "hotter" exhaust side plug as combustion would already have begun by the time the second plug fires. If you read the article, it may make it easier to understand why they did this. Had they had the technology of today and the use of coil packs, they probably could have did away with the whole "two-plug" design and just fired multiple sparks. That would have been impossible to do back then using a distributor style setup. I actually am more impressed with the NAP-Z engine now that I've found that Popular Science magazine and read it. It really was state of the art in its day! These days it's kind of taken for granted. 

As far as "Hemi's," alas we cannot forget the venerable Mitsubishi 2.6L 4-banger that made its home in so many Chrysler "K" cars!


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## rallyrob (Apr 14, 2011)

I hate that POS.underpowered headgasket blower..just like an EA82 subaru..

would there be anyway to get the exhaust plugs to fire just a little faster?Is there a rotor that has a slightly different angle between primary and secondary?Just a little bit more or less would be all thats needed.

the new hemi's have dual plugs for emissions and its all electronic.If multiple sparks would have helped I bet they would have tried that first.


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## smj999smj (Jan 1, 2006)

I'm not aware of any such rotors. As far as the new hemi's...yeah, I guess you're right, but we are talking about Chrysler! Perhaps they are not the best company to rely on as far as engineering ingenuity!


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## rallyrob (Apr 14, 2011)

you also gotta remember that the new hemis have large bores, so maybe multiple spark wasn't enough..


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## rallyrob (Apr 14, 2011)

is there a good reason why nissan didn't put bushings for the cam?Its just bare aluminum so when it wears enough you need a new head and cam retainers.


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## rallyrob (Apr 14, 2011)

also what is the torque specification for the valve train bolts?


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## rallyrob (Apr 14, 2011)

there was a blue relay that was attached to the same bracket that held the AC stuff mentioned earlier.Is that relay for the AC as well?Without the mount for the other stuff its just hanging by the wires..


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## rallyrob (Apr 14, 2011)

Everything is back together but I seem to be getting a bit of valve rattle.I'm not sure if its valve rattle or pre-det but I can change where it occurs if I turn the distributor.Right now I have the distributor advanced to full stop(about 1/8" more than what I had it at before) and the rattle occurs from 1500-2500 rpm. if I retard the distributor that rattle moves up the RPM band,it also seems to grow alittle to the point that if the car is set at stock settings it will rattle from 3000-5000 rpm.So I have it currently set at max advance because I don't spend alot of time driving at 1500-2500 rpm.I'm running 87(need to go fill up asap too) I tried dumping in some octane booster I had in the shop no change.The Spark plugs are all NGK BR6ES because the exhaust plugs were running WAY to hot.

I'm going to go for quick hard drive to get gas and pull the plugs and see what I find.


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## jdg (Aug 27, 2009)

You sure that rattling you're hearing isn't just an extra bit of exhaust noise?
Not an exhaust leak, but the exhaust pulses slamming up against the inside of the manifold when the exhaust valve open. Sounds silly, but a couple of my old Buick 455's used to do it. I could've swore up and down it was pinging...Nope, just exhaust noise. Went away after I put some of that thermal wrap around them.
Just throwing it out there...


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## rallyrob (Apr 14, 2011)

I pulled all the plugs and they all were running a little hot and were showing signs of high speed glazing.I am now running BPR7ES for all plugs,and it seemed to help alittle.Now I am gonna try and adjust the valves to see if that might fix it completely.


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## dudleydoitright (Nov 12, 2011)

For anyone setting timing using TDC, I just tried that the other day and it doesn't seem to be very accurate. However, I did get it close enough that I was able to see the extremely small notch in the crankshaft pulley. I'll be painting it white very soon. 

I looked and looked for that off and on a few times without any luck. Now, I know what it looks like though. It looks like someone took a miniature hacksaw and just barely cut across the top edge of the crankshaft pulley closest to the engine at a 90 degree angle. I guess for balance reasons they couldn't make it more obvious.


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## rallyrob (Apr 14, 2011)

I think my cam jumped a tooth.car wont rev past 4k rpm and its very down on power.where is the cam supposed to be set when the crank is at tdc?


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## dudleydoitright (Nov 12, 2011)

Check my album in this forum for the A14 motor timing chain marks. Not sure if they will help you or not. I always thought both sprockets had a dot that had to line up with each other, but these images are different. It came straight out of the shop manual.

Although I'm an amateur mechanic, I'm thinking that if your ignition timing is ok, I'm wondering how it could be an engine timing problem? On my car the closest I could get to proper ignition timing was 30 degrees so that led me to believe i had an engine timing problem. I've also been told though that the distributor could be worn out so I could be wrong on that assumption.


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## rallyrob (Apr 14, 2011)

when I assembled everything the tensioner didn't move to take up the slack in the chain.the car ran fine for a bit(other than the rearmost cam journal not getting lubricated) then it started running poorly like someone threw a switch so I am betting its jumped a tooth.


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## rallyrob (Apr 14, 2011)

So anyone know where the cam is supposed to be in relation to tdc?I think I found tdc by the screwdriver in the hole method rather than the crank pulley.Crank damper rotated a bit so the mark is off by 1/2" or more..currently the cam keyway is alittle less than 90* from vertical pointing the the driver side of the car(left) and the #1 dot is at roughly 11:30.I found online that someone was claiming the keyway should be straight up at TDC.I'm not sure I believe that because its possible for a car to run with the cam off a tooth but not 90* off.Other than just setting the cam so #1 mark is at 12:00 I don't know what to do.


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## rallyrob (Apr 14, 2011)

crap.It seems when the engine stalled and was difficult to start again it was actually the cam siezing up.The rear most cam journel is scored really badly.However to make matters worse the locating stud for the cam sheared off.When it did that it put a huge crack in the end of the cam,cracked out the cam gear where all of the little holes are in the center..

would the cam and cam gear from an 720 truck be the same?The local pull and save has an 80.82.83.and 84 datsun truck.So one the one from the 82 be the one I am looking for seeing as that is the same year as my car?

If not how hard would it be it put a KA24E from a truck in there?My buddy has a hardbody nissan truck with MPFI(not sure the year though) that his sister ran it out of coolant accidentally and drove it until it stalled.I'm not really even sure if it would be worth saving but I could have the entire truck for $200.


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## smj999smj (Jan 1, 2006)

The cams will probably work, but I'm not sure if their profiles are the same. You can look up the part numbers at NissanPartsZone.com for the 720 and 240SX and compare them to see if they are the same.


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