Timing help

[achb5]

Trying to work out some bugs on a fresh rebuild I just finished. Did the timing belt by the book, or so I thought but when I ran Block 93 yesterday my timing on bank 1 is at -8 and bank 2 +4. Spec is 0 +-6 from what I've read. Can any of the timing gurus offer some advise on how to remedy my situation. Seems like I need to adjust the passenger side exhaust cam. I will redo timing belt procedure if I need to, I just can't think of what I did wrong the first time.

[S4tech2]

The car should be able to to compensate for slight timing adjustments that need to be made from a mistake. If your timing is physically off a significant amount to the point where car cannot correctly compensate then you a rather obvious issue. Also remember timing is advanced and adjusted by the chain connecting the intake and exhaust cam.

[achb5]

Do you think I should just leave the motor as is. No codes and it runs fine. I'm hopeful that there is a mechanical solution to bring the timing closer to ideal. I just don't have a lot of experience with timing the 2.7 and timing in general.

[S4tech2]

You can check the physical timing of the engine on the timing belt and the chains (especially if you need valve cover gaskets) if the physical timing of the engine is correct then I would leave it alone till an issue occurred.

[vavJETTAw36]

IMHO you should always do VC gaskets at the same time of doing timing belt. The VCs take minimal time to get off and it is a cheap insurance that the slack in the belt didn't cause any issues. Plus those bastards should be on the maintenance schedule as they don't take long to leak.


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[airjawed]

How did you do the timing belt procedure the first time? If you did not pop the cams then you didn't do it right.

Redo the timing procedure and do it correctly with cam lock tool.... make sure tool is a quality one. Take your time and observe the pretorque closely.

[achb5]

I reassembled the motor from the bare block. The heads came back from the machine shop with cams not installed. I was very careful to follow the bently on the reassembly. Im sure I have the correct number of links between notches on cams. I also ran a block 94 and tensioners check out, tensioner pads were replaced chains were not. I pre-tensioned timing belt 15nm before torque on cam gears. lock pin and ECS cam bar were used.

As only my bank one value is out of the ideal range Im thinking ill proceed as follows: bank one (pass side) -8 on block 93, ok so 8 degrees or some arbitrary value behind in time. all I need to do is pop the cam gear on bank one and rotate the exhaust cam manually (vice grip on rough cast) some amount either clockwise or counterclockwise. Not sure which direction yet. Then retorque cam gear. Bank two (driver) is sitting great at +4, slightly advanced so as belt wears and stretches timing will only improve. Ill leave bank two alone.

My thoughts please chime in if any of this is way off.

[-Billy]

If I remember correctly the Bentley manual is off on the cam chain specs for one bank. I'd definitely recommend doing a search on the subject. I know there is a proper diagram of it floating around here somewhere.

[Corradovolksb]

This is the correct amount of teeth and placement of the marks. Bank 2 has kicked my ass a few times when installing the cams and tensioner.

[vavJETTAw36]

Just curious, what is Bentley spec? 15 for bank 2? So proper is 16 b1 and 14 b2?


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[achb5]

I used this image for cam chains

[airjawed]

I don't think your chain is off... I think it would either be damaged or run like garbage if it was. The Bentley manual is correct but you really need to study the pictures to see... the above diagrams help clarify things though.

I initially did just pop the one that is behind and advance it by a hair... very very little. I think I did this exact thing... but even after all these miles my driver bank has not stretched. So, I then went in and did both of mine so I'm at +2 on both banks.

Moral of the story... redo them both and get it right.

[megafreakindeth]

Chains do stretch out over time. Being off a tooth will make them move in the 15 degree range. But a 100k+ chain will sag in the 8or so degree range if it's really old.

[achb5]

I don't think your chain is off... I think it would either be damaged or run like garbage if it was. The Bentley manual is correct but you really need to study the pictures to see... the above diagrams help clarify things though.

I initially did just pop the one that is behind and advance it by a hair... very very little. I think I did this exact thing... but even after all these miles my driver bank has not stretched. So, I then went in and did both of mine so I'm at +2 on both banks.

Moral of the story... redo them both and get it right.

Thank you very much for your insight. Am I correct that my bank one at -8 is retarded from perfect time and that the exhaust cam will need to be rotated slightly in the clockwise direction if facing the front of the motor? And likewise for the bank two, my +4 is advanced from perfect time and that a counterclockwise rotation will be necessary?

[achb5]

Chains do stretch out over time. Being off a tooth will make them move in the 15 degree range. But a 100k+ chain will sag in the 8or so degree range if it's really old.

Thanks, will replace chains as a second course of action if need be.

[airjawed]

Thank you very much for your insight. Am I correct that my bank one at -8 is retarded from perfect time and that the exhaust cam will need to be rotated slightly in the clockwise direction if facing the front of the motor? And likewise for the bank two, my +4 is advanced from perfect time and that a counterclockwise rotation will be necessary?

Yes... when standing in front of the engine everything is rotating clockwise... so the cam that is at -8 will need to be popped and the wing moved clockwise to advance it some. The one that is at +4 needs the wing turned counter-clockwise to retard it. Doesn't take much! I would mark the wing and cam so you can know where it was and then you can use your cam lock tool on just the one side you are working on so that you can control it better. Don't let the wing spin freely... pop it with the tool in place.... otherwise you might have a valve touch when the cam spins possibly.

[achb5]

Excellent advice, thank you very much.