# timming chain questions.



## skeen (Mar 25, 2007)

I have a 86 nissan with a z24 4 cly. engine. when I put the timing chain and sprockets back on I lined the marks on the chain up with the marks on the sprockets. when the chain turns are the marks on the chain and the marks on the sprockets always supposed to line back up? any advice would be great.

thanks,
Scott


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## legoman786 (Oct 19, 2006)

They are ALWAYS supposed to line back up. If not, you have different sized sprockets.


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## skeen (Mar 25, 2007)

the sprockets are brand new I got a chain and tensioner too. what do you think I"m doing wrong?


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## MOUNTAINMAN444 (Apr 23, 2007)

They will line back up at "top dead center" (TDC) of #1 cylinder only. If when you started disassembly you had the #1 cylinder at TDC, took off the gears and chain and then installed the new ones without letting anything move. If nothing moved, when you rotate the crank the marks will line back up everytime you take the engine through a complete set of rotations and end up at TDC of cilinder #1. 

More simply put, you start with everything at TDC of cylinder #1. Take it apart, put it together (without letting anything move). Then as you rotate the engine (by hand) everytime you come up on TDC of cylinder #1 the marks should line back up. They may line up at other times, but at TDC of cylinder #1 is the only time that counts. If they don't DO NOT CRANK THE ENGINE. It will knock the valves out of the heads and you will have a giant problem.
Joe


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## skeen (Mar 25, 2007)

well I don't think it was at TDC when I took it off I think it jumped time. and the when I was taking off the cam shaft sprocket the the cam shaft moved a little bit. if I put every thing back a TDC will it be ok?
thanks,
Scott


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## legoman786 (Oct 19, 2006)

Yeah, when you put #1 at TDC, then it should be fine.


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## skeen (Mar 25, 2007)

well I put every thing a TDC and the the marks on the chain didn't line up with the marks on the sprockets. I must be doing some thing wrong. can you give me any advice?

thanks,
Scott


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## legoman786 (Oct 19, 2006)

Move the chain to line it up. DO NOT move the sprockets while doing that. 

Correct me if I'm wrong, but the mark on the camshaft should be at the top and the mark on the crank should be at the bottom.


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## skeen (Mar 25, 2007)

my manual says to turn the cam shaft until the number one front clyinder valves are closed, and then turn the crank shaft until the number one piston is at TDC. and the keyway in the crankshaft sprocket should be on top. the timing marks on the chain should align with the marks on the two sprockets and be positioned on the right side when viewed from the front. 

and I did all that and the marks lined up, but when I turned the crank shaft by hand to see if they would line back up they didn't.


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## Smith1000 (Dec 29, 2005)

From what you described, I think you might be okay. I worked on mine awhile back. Had to remove the head. It was kind of tricky. Here is what I recall on the timing alignment:

If you got it all lined up and it was on top dead center (compression stroke), you should be okay. What I did when I work on mine was look at the distributor rotor and watch to see it (the rotor) come around to the plug wire hub for the #1 cylinder (right before-ready to fire on #1 tower), distributor cap off. That is a double-check to make sure you have it on TDC, the compression stroke. You have to get oriented on the distributor first to figure out your firing order (which hub/tower is for the #1 cylinder). Also, I checked to make sure my valves for cyl#1 were closed (for compression). In addition, your marks all are lined up (chain and cam). The little hub (keyway) and sprocket hold are on top. Also, can look at the crank pulley for the timing marks. It will hit TDC for the compression and exhaust stroke. You want the compression stroke TDC. 

Make sure you are not looking at TDC -exhaust (which is the compression stroke for cyl #4 (the paired cylinder). That would be TDC, exhaust stroke for the #1 cyl. One will be on compression and one on exhaust. If your distibutor rotor is crossing the #4 cyl (I believe #4 is paired with #1) when #1 is at TDC, then you are on TDC (exhaust stroke, #1 cyl). The distributor rotor will be 180 degrees off from where it should be for #1 cyl.

After you have it back together and you were to then rotate the engine with a wrench on the crankshaft, you won't see the marks line up again until you get back around to TDC on the compression stroke for #1 cyl. In between the #1 cylinder compression stroke, the #1 cyl will come back up again to TDC again, but that is TDC for the #1 cyl exhaust stroke. For the exhaust stroke, your #1 cyl exhaust valve will be open (tight-pressure on it) and the intake will be shut (no pressure). Rotate it around again to TDC (#1 cyl compression stroke). The next time around it should hit TDC, compression stroke. From what I recall, it does not take very long to get that engine rotated around through all the cylinders. Goes pretty quick.

To double-check your TDC (compression stroke) position though, rotate it around again to TDC and see if the marks line up. Look at the distributor rotor next to see if it is about to rotate to the #1 cyl plug (that orientation will not have changed if the distributor has not been removed). Then, look at your timing marks. Hope this helps. Good luck with it!


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## skeen (Mar 25, 2007)

I guess I'm not doing some thing right because the marks on the chain still aren't lining up with the marks on the sprockets. I have a another engine just like the other one so I'm going to take it apart and look at it and see if I can find out what I'm doing wrong. thanks for your help. 
scott,


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## Smith1000 (Dec 29, 2005)

Did you have the chain completely off from the crank? If so, and it was not put back on the crank in the exact position it came off, the marks won't line up on the cam sprocket above since the bottom reference is off. If everything is at TDC, compression, the chain could be moved to match up to the reference points (if you want to get the chain to match up). 

If it were me and I knew for sure the #1 cylinder was at TDC (compression) and both valves were closed for the #1 cylinder with the keyway up (for compression), then it could be properly referenced even with the chain marks off. If so, it should run even with the chain marks off (if it had been taken all of the way off). I would look at the distributor too to see where the rotor is sitting. It's just a chain on a couple of sprockets though. Check it real close!


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## skeen (Mar 25, 2007)

yes I had the chain complitely off. the distributer is off the front cover is off. so how do I find TDC compression with the distributer off? and witch valves are for the #1 cylinder?

thanks,
scott


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