S2000 Under The Hood S2000 Technical and Mechanical discussions.

Can't Get perfect TDC

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Old Aug 10, 2012 | 07:43 PM
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Default Can't Get perfect TDC

So I am in the process of rebuilding the motor and have been following the manual to a T. Right now I am struggling to get perfect TDC. No matter what I do when the timing chain sprocket lines sit even with the head the lines on the crank pulley either sit to the Left or the Right.

Here are photos. Please tell me which one works, i have done redone and redone this over the past hour to no avail.



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Old Aug 11, 2012 | 08:07 AM
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You are obviously a tooth or two off.

Remove the camwheel and re-time it.
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Old Aug 11, 2012 | 10:39 PM
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Those photos are a tooth apart....
After looking through the manual I found a page about lining up the colored links on the cam chain with the little dots on the sprocket. Turns out after doing this that the second photo is correct TDC. I did it all correctly and hopefully when I start the motor everything won't explode
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Old Aug 11, 2012 | 11:20 PM
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You can always mechanically confirm TDC with a depth gauge, through the spark plug hole, touching the piston.
I think it can be as simple as a steel rod - no sharp ends - you put through the spark plug hole and let it rest on the piston while turning the crank.
You will see TDC - even feel it if you hold the steel rod - and if you then look at the crank pulley you can see if any of the marks line up.
That will be true TDC.

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Old Aug 12, 2012 | 06:42 AM
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The crank pulley will ALWAYS line up with TDC since it is keyed to the crankshaft. The thing he needs to be worried about is not being a tooth off with the idler gear. This in turn would cause his valve timing to be off causing potential detonation from valves hitting pistons.
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Old Aug 12, 2012 | 07:33 AM
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Do you have a non-oem head gasket?

Is the TCT installed when looking at the marks, or at the least is the drivers side of the chain tight?

The keyway didnt fall out of the crank correct?

These are 3 things that can get the results you are describing.

If all these check out, do a TDC test on cylinder 1 with a long dowel or screwdriver. Confirm that when the piston is at TDC, the white mark aligns with the pointer.

If not, you could have a possible separated pulley (the outer ring of the crank pulley moved out of time)
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Old Aug 20, 2012 | 05:10 PM
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I have a Cometic Headgasket. Everything else is correct, TCT installed, keyway is in.
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Old Aug 20, 2012 | 07:40 PM
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My motor is like yours in the first pic. Its slightly rotated to the right at tdc. I started a topic asking the same thing and someone linked to another topic about the same thing as well. I guess its pretty common. After i changed my HG and set it to tdc like that it the car runs fine, i dont know why its off like that.
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Old Aug 21, 2012 | 05:06 AM
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dont worry with the marks on the chain, set the crank to tdc, then just make sure the lines on the cam gears are correct. You dont really need to worry about the position of the idler gear at all.
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Old Aug 21, 2012 | 11:08 AM
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The problem he is having is the same i was. You cant get the crank pulley and the cam marks to all line up perfectly. This is the thread i started. https://www.s2ki.com/s2000/topic/961...#entry21834873
It was like that when i took it apart and when i put it back together and the car runs fine so i know the timing is right. Just wierd how its off.
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