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New Timing Chain but still huge TDC gap (R107 450 SL -75 ) - What is wrong?

  • pholmqvist
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25 Apr 2021 18:52 #274383 by pholmqvist
Hej!

I have replaced all 4 upper guiding rails, both cam sprockets and the timing chain on my 450 SL -75 US import to Sweden 1991. Prior to doing this the TDC mark was approx 15 degrees of when passenger camshaft mark was aligned (cylinder 1 at TDC I guess). Now the gap at crankshaft TDC mark is approx 8 degrees off when passenger camshaft is aligned.

I have attached a couple pictures when the passenger camshaft is aligned showing the status of crankshaft mark - 8 degress off - and driver side camshaft (2 degrees off). The chain is not having any slack when tensioner installed and I have turned engine 10ish time CW.

Any ideas what has gone wrong?
Any explanation why I still have as much as 8 degrees off mark?
Do I need to add "wood ruff" key on driver side?
Is there any other test I can do to check things before putting everything bacK
Could it be something with the tensioner after all?

I have used MB parts for all except cam sprockets and upper left tensioner guide rail plastic ( not in stock for 3 months in Sweden!).

Any guidance greatly appreciated, would be great to get her running now when the Spring finally has arrived.

Mfg/Kind Regards
Patrik 

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  • Racediagnostics
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25 Apr 2021 19:38 - 25 Apr 2021 20:39 #274388 by Racediagnostics
Hi, I rebuit my engine and also found the timing mark was off.

The timing mark is not to be used for detailed analysis but an indication only for assembly. So before you think about offset woodruff keys, you need to check the timing of this way.

www.startekinfo.com/service/download-doc...7/M117_45/05-215.pdf

This will tell you exactly the timing.

I checked mine this way and it turned out to be perfect.

My pictures here.

sternzeit-107.de/en/forum/forum-107en/24...nce?start=270#268815
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xxxxxxxxxxxxxxxxxxx

Hallo, ich habe meinen Motor umgerüstet und festgestellt, dass die Zeitmarke nicht stimmt.

Die Zeitmarke dient nicht zur detaillierten Analyse, sondern nur zur Montage. Bevor Sie also an versetzte Waldmeisterschlüssel denken, müssen Sie das Timing auf diese Weise überprüfen.

www.startekinfo.com/service/download-doc...7/M117_45/05-215.pdf

Dies wird Ihnen genau das Timing sagen.

Ich habe meine auf diese Weise überprüft und es stellte sich heraus, dass sie perfekt war.

Cheers
Jim

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1979 450SL - 2002 XK8 4.2
Last edit: 25 Apr 2021 20:39 by Racediagnostics.

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  • pholmqvist
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25 Apr 2021 21:05 #274397 by pholmqvist
Hej Jim,

Thank you for pointing me towards that document, however not that straightforward to really grasp how to double check. My engine no is 117982-12-c36991. Any advice on how to decipher the content that you provided into a practical test to check how far off I still am or not?

I must confess looking at your engine rebuild pictures that I am mega impressed - what an effort and great result!

Kind regards
Patrik

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