Jumped timing chain / one link on sprocket...

[alt77]

When rebuilding my tensioners separately, the Left side chain link had slipped a link prior to installing the tensioner. ( 83 Carrera 3.0 motor,, non turbo.)
My concerns are; a) Can the Rt side cam be reset without removing the chain or having to reset the Rt side cam? b) Can the Lt cam be reset by itself as long as the Rt cam and chain remain tight ? c) Should the timing chain be removed /reset cams / then reinstall chain?

I do plan to remove the motor if necessary for ease of torquing down the cam nuts.
Or, depending on the responses to this post, raise the car safely enough to do the work on the ground.

[ben parrish]

Each is set independently. Chain and cam stays in place; sprockets rotate and lock in place with a dowel pin. It’s really not that hard

[alt77]

That's a relief. So obviously remove the nut / then find out which way the cam is offset / remove the pin / rotate cam to TDC / tighten nut .

[ben parrish]

That’s it.

[Marc Bixen]

So ben, "That simple"? Forget cam timing! Just put the nut back on! Really. alt77 Do Your Homework, it's not THAT easy.

[ben parrish]

Well of course you have to make sure the lift is correct for the valves. He asked if you have to remove the chain and the answer is no..just index the sprocket and verify the timing. It’s not rocket science, just cam timing. A dial gauge and a little time is all...

[ben parrish]

This is a good help...don’t overthink this.
http://www.youtube.com/watch?v=0t7gpEBJEf4

[alt77]

In reply and concern of my local area mechanic, Marc. I will differently check the valve on #1 to confirm the cam location. One link jump has moved the cam either to the right or left by one link. Ben is recommending repositioning the sprocket by the means of one pinhole in the rotation of the cam to TDC. Right Ben? I will not remove the chain. Question for Marc; Should I also check the #4 valve as a final procedure?

[Eagledriver]

You don’t nessesarily need to remove the cam bolt or nut. You can leave the right side alone, just check to make sure timing is in spec. The left side can just be repositioned 1 tooth to get it back in time. Be careful when rotating the cam or the crankshaft so you don’t hit a valve with a piston. The two cams rotate in the same direction and the same amount so you can just rotate the left cam so it’s oriented to the same “angle “ as the right cam. Once you get the chain back to the correct tooth, just check the timing. If you loosen the sprocket, you’ll have to go through the timing procedure.

-Andy

[alt77]

Ok, thanks Eagledriver; you are suggesting that ' it is possible', to relocate the chain-link manually, while the tensioner is under tension or, do I remove it for the ease of correcting the chain jump by one link? Again, are you suggesting that I can rotate the cam sprocket easily? Yes, I will check the timing as most videos and manuals suggest after I try the cam rotation. I've read to move the cam with a slight jerking motion to assist the valve during the rotation...thanks for the heads up.

This sounds closer to what I had hoped it would involve. I want to proceed carefully with all the info in mind to simplify the repair and not create more work than necessary.

[alt77]

In addition to my replay... Using the slack in the chain, can the idler sprocket be the location to correct the chain jump...and not at the cam? My thoughts are correcting the jump on the idle sprocket will automatically move the cam sprocket (left or right) into TDC. Logical or not possible?

[yelcab1]

With all due respect tp alt77, get a buddy locally to do this for you while you watch....

[gomezoneill]

It's not that easy!

[Flat6pac]

You’ll need to be able to see both cam ends to know where you’re at
Use the dot or key way on the fixed side for reference
You can’t turn the crank because of possible valve interference
Drop the tensioner off and compress and pin tensioner
Turn the cam inside the chain to match the fixed, correct side
Reinstall the tensioner and pull the pin
If your dots on the cams are equal you should be good,
Turn the crank to Z1 and cam dots should be either both up or both down
Turn 720 degrees with no intereference you should be good to go
Bruce

[911pcars]

Originally Posted by alt77

When rebuilding my tensioners separately, the Left side chain link had slipped a link prior to installing the tensioner. ( 83 Carrera 3.0 motor,, non turbo.)
My concerns are; a) Can the Rt side cam be reset without removing the chain or having to reset the Rt side cam? b) Can the Lt cam be reset by itself as long as the Rt cam and chain remain tight ? c) Should the timing chain be removed /reset cams / then reinstall chain?

I do plan to remove the motor if necessary for ease of torquing down the cam nuts.
Or, depending on the responses to this post, raise the car safely enough to do the work on the ground.

There are some issues with this situation (in no particular order):

- How far did the crank rotate (if any) when the LS chain "slipped a link"?

- Is the Right bank cam in time?

- Lining up the dots at 12 o'clock is a rough estimate, but it does indicate cyls. 1 and 4 are at TDC with #1 end of compression. The many holes in the cam sprocket are there to fine tune the timing specs.

- Rotating the crank with cam timing "off" could result in valve-to-piston clearance issues. I would back off all rocker arm adjusters on the LS bank, maybe all to reduce crankshaft rotating effort. Rotate crank in clockwise direction only.

- When cam timing, the camshaft is rotated relative to the crank (the crank is stationary at TDC, only rotating to confirm valve opening and closing specs). Thus, you need a method to independently rotate the cam.

- Can be performed with engine installed. Easier with engine removed. Support engine, remove muffler and rear engine mount(s) for access.

Hope this helps,
Sherwood

[Marc Bixen]

Sorry alt, I’ve been Out of town. Will answer tomorrow.

[boyt911sc]

Originally Posted by yelcab1

With all due respect tp alt77, get a buddy locally to do this for you while you watch....

Alt,

It is good to ask and seek advise. Have you done a cam timing before? This is a good time to get someone to assist you because your understanding how the cam timing is done is questionable. People with experience could do it with the motor installed but I would rather do it with the motor on an engine stand. If you are in a hurry and needs to get the car back on the track soon, doing the cam timing in situ makes sense. But if you are at home, why make the condition more challenging for you. Pull that motor out and take your time to fix the problem.

Are you using a mechanical tensioner to keep the timing chain taut? Keep us posted.

Tony