[Harvey]

In preparation for a complete belt/roller/waterpump changeout on my 1994 968 6-speed, when I line up the camshaft gear alignment mark perfect w/the rear cambelt cover V-notch....the alignment marks on the upper balance shaft sprocket are mismatched by about the width of the V-notch (close but not perfect). At the same time, looking through the small round inspection hole in the bottom front cover of the clutch housing, there are three alignment marks (lines) on the flywheel. The center mark is close but not perfectly lined up with the center of the round hole. Looking down from the top through the square hole in the clutch housing, I can't see any markings for alignment...although there could be a marking that's not visible from the angle I'm able to look into the hole. Without taking off the lower cambelt cover, I can't see the alignment marks of the lower balance shaft sprocket. A round dowel in the spark plug hole verifies that the piston is TDC.



Important questions:



1) Am I at TDC and ready to install the flywheel lock?



2) Is the discrepency in alignment marks at the different areas an indication that I need to tweak something to get them to align? Would this difference affect engine timing or performance somehow?



Thanks, very much! I don't have much time to work on the car but, little by little, I'll get there (I hope).



Harvey

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[Greimann]

[quote name='Harvey' date='May 6 2005, 01:05 PM']I

1) Am I at TDC and ready to install the flywheel lock?



2) Is the discrepency in alignment marks at the different areas an indication that I need to tweak something to get them to align?  Would this difference affect engine timing or performance somehow?

[right][post="4408"]<{POST_SNAPBACK}>[/post][/right][/quote]



Yes, you are at TDC with the cam mark aligned and the dowell trick to verify.



The marks are very close, but not exactly, vernier calipers perfect. You will also find that you may need to slightly tweak the posittion of the crank to get the flwheel lock in too. I rotate the crank clockwise off the mark (when standing, facing the engine) to get the lock in. Once you get the lock bolted down, make a note as whether the cam gear mark is biased to the left or right of exactly aligned, that way you can set the balance shaft marks accordingly.



Note also when you get the old timing belt off, the cam gear will rotate 1 tooth counter clockwise due to spring pressure. You will have to force the gear back on the mark when you install the new belt. Take your time and quadruple check the alignment before pulling the pin on the tensioner.



The balance belts are a bit easier to get right. You can clearly see if they are close to the mark or 1 tooth off.

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[Harvey]

Greimann,



That's the kind of information that will make the job MUCH less eventful (and keep me from trashing a good engine). These kinds of little hints are really helpful and are not found in the manuals.



It makes sense to me that all the positioning marks should be pretty well on. I wonder if moving the camshaft crank a bit (if it can be done at all) to have it jive with the other TDC marks at the other places might make for a better running engine? Or perhaps this is as good as it gets or needs to be.



Thanks very much,



Harvey



[quote name='Greimann' date='May 6 2005, 03:22 PM']Yes, you are at TDC with the cam mark aligned and the dowell trick to verify.



The marks are very close, but not exactly, vernier calipers perfect.  You will also find that you may need to slightly tweak the posittion of the crank to get the flwheel lock in too. I rotate the crank clockwise off the mark (when standing, facing the engine) to get the lock in. Once you get the lock bolted down, make a note as whether the cam gear mark is biased to the left or right of exactly aligned, that way you can set the balance shaft marks accordingly.



Note also when you get the old timing belt off, the cam gear will rotate 1 tooth counter clockwise due to spring pressure. You will have to force the gear back on the mark when you install the new belt.  Take your time and quadruple check the alignment before pulling the pin on the tensioner.



The balance belts are a bit easier to get right. You can clearly see if they are close to the mark or 1 tooth off.

[right][post="4411"]<{POST_SNAPBACK}>[/post][/right][/quote]

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[Greimann]

Well these tips are part of the oral history that we pass on to each other. With all of the electrronic archiving, we still don't know everything we know.



If you were building a small block Chevy, there are tools and devices that allow you to "degree in" the cam timing. With this motor, I know of no techniques that allow you to do that, so getting it on the correct tooth on the timing belt is as good as it gets.

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