Setting 240 at TDC on Compression Stroke

[CobraBytez]

I'm going through the removal process for my cylinder head, and I know how to set the engine at TDC, but how do you know whether its on the compression stroke?

[nzmoman]

check the search button, you will find all you need to know about TDC and compression...there is a ton of info there...

[45psi]

hey nismoman, i dont know what site your talking about but its not this one.

i just spent 3 hours searching nico club about how to make sure my tdc is on the compression stroke. trust me i been beating up the search button to no avail.

so next time, nzmoslut, please answer the question, cause the search function sucks like your mom.

[NISSAN240SX12]

yes it needs to be a compression stroke to set the TDC. Come on ppl no need for bs trash talk.

[hawk83]

hes right though, got my a** chewed couple times. spent all day using the search button and couldnt find jack. freakn sucks when all you get is "use the search button" guess what? i dont have a search button anymore, i wore a hole in the damn thing so give me some freakn love people. HELP OUT

[steamer1227]

do have a DOHC?

[spank044]

hes right though, got my a** chewed couple times. spent all day using the search button and couldnt find jack. freakn sucks when all you get is "use the search button" guess what? i dont have a search button anymore, i wore a hole in the damn thing so give me some freakn love people. HELP OUT

hey nismoman, i dont know what site your talking about but its not this one.

i just spent 3 hours searching nico club about how to make sure my tdc is on the compression stroke. trust me i been beating up the search button to no avail.

so next time, nzmoslut, please answer the question, cause the search function sucks like your mom.

DOHC the cams will be facing out. The search button works just fine, try using different words and don't be to exact. Type in timing and you get 3 pages, most of which contain your answer.

[JNM240]

Easiest way for either or DOHC or a SOHC is to turn the crank until the 0* mark lines up with the timing mark. Thats top dead center on compression.

[the converted]

Easiest way for either or DOHC or a SOHC is to turn the crank until the 0* mark lines up with the timing mark. Thats top dead center on compression.

Not quite. But to answer the question, take off your distributor cap and when the rotor is lined up with where the plug wire for cylinder one would go you will on the compression stroke. Now just move the crank until you are at the tdc mark.

The search function on this site is only as good as the people who are titling their threads. You have to learn to think about what someone would have asked as a question to find the good threads.

[steamer1227]

you guys are almost there you have to make sure that the camshaft is in the right position..

spank044 has it

take off the oil cap make sure that the cam lobe is pointing towards the exhaust side other wise you have to spin it 360 degrees

[driftneil]

you guys are almost there you have to make sure that the camshaft is in the right position..

spank044 has it

take off the oil cap make sure that the cam lobe is pointing towards the exhaust side other wise you have to spin it 360 degrees

Boom, there it is....Take it and run with it.

[OutToWinPAHC]

top dead center.... hmmm when then piston is at TDC is it at compression or decompression? Pure TDC is pure TDC no matter how you look at it.

[NISSAN240SX12]

your lobs should look like this at a compression stroke. TDC.

[vancouverbc]

look up top dead center in tutorial link in my signature or google 240sx top dead center tutorial

[steamer1227]

exactly what i said as you can see in the pic the exhaust lobe which is the one you'll see with the oil cap off is pointing towards the exhaust.

decompression =

[S13_love]

Type in timing and you get 3 pages, most of which contain your answer.

If you type in timing...you get 24 pages, most of which doesn't contain an answer.

[hawk83]

i get how to set timing and tdc, but which way do lobs face for s14 sr.?

[Xj220gt]

They face out, make sure you get the right TDC and not BDC! either do it by looking at the lines on your harmonic balancer (second mark from the far left mark I believe) or take off the distributor cap and make sure the rotor is facing towards the number 1 cylinder plug.

http://www.nicoclub.com/articles.php?id=105618

that will show you exactly what you need. make sure you read through all of it. the distributor alignment picture will be towards the bottom.

[KoopaTroopa]

surprised that no one mentioned putting a screwdriver into the first cyl sparkplug hole

[driftneil]

Thats a no-no my friend. You will score your piston.

[spank044]

If you type in timing...you get 24 pages, most of which doesn't contain an answer.

Sorry I didn't spell it out in big crayon, I just assumed that if you wanted to know KA timing then you'd look in the KA section, but sometimes it is just too simple.

[vancouverbc]

surprised that no one mentioned putting a screwdriver into the first cyl sparkplug hole

Index of all Tutorials

Tools

1.27mm shallow socket for rotating the crankshaft. you can rotate from below or above engine.2. chalk and paint.3. small flat head screwdriver and adjustable pliers to remove relays

Top Dead Center(TDC) occurs when the piston head in cylinder 1 is at it's highest point. If you take the sparkplug out, you can look through the hole and see the top of the piston. The distance from piston head to top of hole is about 147 mm(5.78 in). There are two top dead centers. Once when the piston comes up to compress the gas and once when the piston comes up to push out the exhaust from combustion.

Moving the crankshaft

You can move the crankshaft by turning the ignition key to start for an instant several times until you see the timing marks. You can paint a mark about a foot clockwise past timing marks to warn you that timing marks are close. Always rotate clockwise. You can use chalk to make the timing marks easier to see.( to avoid flooding, remove the egi and egi pump green relays or unplug the 4 injector electrical connectors at the injector)

Exhaust vs Compression top dead center

The easiest way to know that your top dead center is compression tdc is to observe the postion of the rotor by removing distritbutor cap. It will be pointing close to cylinder one on the compression stroke and close to cylinder 4 on the exhaust stroke. This, of course, only works if you distributor timing is in the normal range. If your timing is really off, you will have to place your hand on the sparkplug hole(sparkplug removed) and feel the pressure build up on the compression stroke as you rotate crankshaft by hand.

alternativelyNote here the position of the cam lobes on #1 cylinder. They are facing outwards which means its at TDC on compression stroke. If the #1 cylinder cams are facing inwards then just rotate your pulley another 360 degrees until they are facing outwards.



Crankshaft goes around twice for every time the rotor goes around once.

If you dont have marks on crankshaft pulley

You will have to place hand over sparkplug hole to determine when it is the compression stroke. then, rest a screwdriver on piston head and rotate crankshaft until screwdriver sticks out the most.

Modified by vancouverbc at 3:42 PM 8/10/2008

Modified by vancouverbc at 12:58 PM 8/16/2008

[PapaSmurf2k3]

Thats a no-no my friend. You will score your piston.

No you wont... who the hell told you that? The only way that would ever score your piston was if you use a small thin screwdriver and it dropped down into the hole completely, and you re-assembled your top end and left it in there, and then tried to run the engine.

[driftneil]

No you wont... who the hell told you that? The only way that would ever score your piston was if you use a small thin screwdriver and it dropped down into the hole completely, and you re-assembled your top end and left it in there, and then tried to run the engine.

Alright, metal master. Anyone can scratch metal, with a metal screwdriver. If your rough enough, anything can happen. The fact is, you shouldn't chance it. It's a point of advice, not saying it's going to happen everytime. But still you shouldn't do it. Just trying to save someone problems, down the road

[hawk83]

i used a piece of a broken plastic hanger with tape wrapped around the end, just in case. better safe than sorry ya know?on another note, when i reached tdc, the chain seemed tight between the cams, left it their and the next morning it didnt seem as tight. Is this because the chain tensioner operates with the oil pressure, and because my swap isnt up and running (no oil pressure) its slacking over time. sounds right to me but im not 100% sure . It didnt seem to do that before hand, but i pulled the upper guide off, and removed the tensioner to check it out and now it seems to be doing it. There was noticeable rubbing marks on the guide too.

[PapaSmurf2k3]

Alright, metal master. Anyone can scratch metal, with a metal screwdriver. If your rough enough, anything can happen.

Not if the metal you are trying to scratch has a higher hardness than the metal you are trying to scratch with.

Even then, you said SCORE. Putting a light scratch on the piston isn't going to do a damn thing. Its probably coated in carbon anyway. SCORING the piston would take a HELL of a lot of force.

But yes, I suppose there is the off chance that you own a badass carbide tipped screwdriver that weighs a s*** ton, and you let it slip out of your hands from a significant distance and it falls down the hole and hits the piston with enough force to put a small dimple in it.

Sorry for the sass... I've had a bad day (Friday the 13th + customer issues at Ford )

[driftneil]

Not if the metal you are trying to scratch has a higher hardness than the metal you are trying to scratch with.

Even then, you said SCORE. Putting a light scratch on the piston isn't going to do a damn thing. Its probably coated in carbon anyway. SCORING the piston would take a HELL of a lot of force.

But yes, I suppose there is the off chance that you own a badass carbide tipped screwdriver that weighs a s*** ton, and you let it slip out of your hands from a significant distance and it falls down the hole and hits the piston with enough force to put a small dimple in it.

Sorry for the sass... I've had a bad day (Friday the 13th + customer issues at Ford )

Not a prob, sass it up....Made me laugh, picturing this huge screwdriver.

[steamer1227]

regardless of the damage it can and can not do the easiest way to do it is to take 3.7 seconds and remove your oil cap bend down and look inside....wha lah ........ like feeding a fat kid a peanut butter cup....EASY

[le_ryan]

i used a piece of a broken plastic hanger with tape wrapped around the end, just in case. better safe than sorry ya know?

you guys DO know an engine is made to contain explosions .. right ?I se it to TDC with a screw driver ALL the time, never a problem.

[PapaSmurf2k3]

regardless of the damage it can and can not do the easiest way to do it is to take 3.7 seconds and remove your oil cap bend down and look inside....wha lah ........ like feeding a fat kid a peanut butter cup....EASY

Until you get someone doing a search and finds this thread... and they have their cams off.