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Timing chain. Am I off a tooth? L20b


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timing%20chain%20023_zpsgadg84ud.jpg

 

Its an L20b.  If I re-position the cam sprocket to position 2 or 3 will I make that up or make it worse.

 

Obviously I don't want to pull the front cover if I don't need to.  But if I am off a tooth then we have no choice.

 

We pulled the head off to change the gasket, we didn't think the chain slipped.......but now I am questioning that.  

 

So reposition the sprocket, or pull the cover?

 

 

 

 

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did you mark the chain in relation to the sprocket at any point before the gasket swap?  Double check the motor is at TDC, if it is then I guess it couldnt hurt to try and rotate the gear to see if any other position helps make that right.  I have done this exact thing, in the end I pulled the cover to be certain, turns out I didnt have to.

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timing%20chain%20023_zpsgadg84ud.jpg

 

First make damn sure that you turn the crank clockwise up to and stop at TDC. If you overshoot and back up you will introduce slack onto the tension side of the chain and get an incorrect reading. If you overshoot TDC, back well up and begin again. It may take several tries but it's crucial to getting a good reading.

 

IF you are precisely at TDC then the horizontal etch line is too far to the left of the notch.

 

You are on the number 1 position..... all L20Bs come from the factory in the #2 position. This is why the cam is so advanced.

 

 

Simply loosen the cam sprocket bolt, but don't remove yet.

Set the engine to TDC as described above.

Wedge the timing chain so the tensioner cannot fall out.

Now remove the cam sprocket and replace on the #2 position.

Put everything back together and reset TDC.

 

You should now find the etch mark about one width closer to the notch on the sprocket. Each etch mark width and number change on the sprocket is 4 degrees.

 

Each tooth moved is 9 degrees so this won't work.

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did you mark the chain in relation to the sprocket at any point before the gasket swap?  Double check the motor is at TDC, if it is then I guess it couldnt hurt to try and rotate the gear to see if any other position helps make that right.  I have done this exact thing, in the end I pulled the cover to be certain, turns out I didnt have to.

We did mark the chain in relation to sprocket.  

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timing%20chain%20023_zpsgadg84ud.jpg

 

First make damn sure that you turn the crank clockwise up to and stop at TDC. If you overshoot and back up you will introduce slack onto the tension side of the chain and get an incorrect reading. If you overshoot TDC, back well up and begin again. It may take several tries but it's crucial to getting a good reading.

 

IF you are precisely at TDC then the horizontal etch line is too far to the left of the notch.

 

You are on the number 1 position..... all L20Bs come from the factory in the #2 position. This is why the cam is so advanced.

 

 

Simply loosen the cam sprocket bolt, but don't remove yet.

Set the engine to TDC as described above.

Wedge the timing chain so the tensioner cannot fall out.

Now remove the cam sprocket and replace on the #2 position.

Put everything back together and reset TDC.

 

You should now find the etch mark about one width closer to the notch on the sprocket. Each etch mark width and number change on the sprocket is 4 degrees.

 

Each tooth moved is 9 degrees so this won't work.

Ok Datzenmike, before I pull the cover I will rotate the sprocket to #2.  Turning clockwise.  I'll rotate it a few times and double check the position of the piston at TDC.

 

I'll repost in about an hour or so.....

 

Thanks

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All you need to be sure of is that you turn clockwise up to and stop at the TDC mark. If you go over, back the engine about 1/4 turn counter clockwise and start again. I've done this 6 or 7 times to get it correct. Once past the TDC mark you've missed it and simply backing up to TDC will introduce error in the form of chain slack where the cam moves but the crank does not.

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Guess I fucked that up. What was I thinking?

 

Leave on #2. Block chain, take sprocket off and move one tooth clockwise. This will remove 9 degrees or about two widths of that etch mark and be back in the correct position. Moved one tooth, the cam will need to be rotated slightly clockwise also for the pin to fit in the back of the sprocket.

 

There is no harm running the engine with altered can events. It will just not be very efficient and lack power at low speeds

 

Sorry about that.

 

No you still do not need to remove the timing cover.

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yes, post #14 is practically dead on, if you're at TDC....

 

Funny story........

 

My timing chain is stretched pretty bad, and I don't really want to replace it right now.

 

On hole #3 I was still retarded from the notch... Seriously stretched. 

 

I decided to put it back on #2 hole retarding it 5 degrees even further -- BUT i then advanced it 1 hole tooth at the sprocket, now advancing it 9 degrees. spun her around a few times and then placed back on TDC.

.....What do you know, timing is dead on.

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Yup, there are 40 teeth and 360 degrees, so each tooth represents nine degrees. Or a little over two number changes. This moves all the stretch to the tensioner side of the engine. As long as the notch is just below and to the right as pictured, it's all good.  

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Got it started.  still runs like shit.  I'm still thinking we have some sort of carb issue.  if we spray starter fluid anywhere close to the base of the weber the idle increases.  it has to be a vacuum issue.

 

We ran the car til the thermostat opened.  I'll drain it in the morning, then fill it again.   The back story is oil in the radiator.  You can follow that under project datto "The New Guy".

 

However, the car ran so great for the 1st several weeks, then gradually had issue with idle, then just kinda fell apart.  Hoping we solved the oil to coolant issue.....now just need the fucker to run well again.

 

Thanks for all your input.....we needed it!!!!

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