190E Top Dead Center
 

I have purchased a 1985 190E which was run previously in Mercedes Club Racing. I am converting the car to run in SCCA. Unfortunately, the previous owner has removed a lot of what used to be under the hood, particularly electronics. Needless the say, the car doesn't run very well.

So on to my question:

I am planning to remove the cylinder head and have a valve job done professionally. In the process, I moved the engine to TDC by aligning the pointer on the timing cover with the mark on the crankshaft pulley. When I removed the camshaft cover, I noticed that the notch on the camshaft flange does not align with the cylinder head.

Should both the crankshaft and camshaft be aligned with their respective marker at top dead center? If not, which (the crankshaft or the camshaft) is a better indicator of TDC?

And is this possibly the reason the engine doesn't run well?

TDC by definition is the #1 piston all the way up. Is this the 4 or 6 cyl engine?
Gilly

This is the 4 cylinder.

The more I read about this, it appears that the marks not being aligned is a sign of timing chain stretch. Does this sound accurate?

Align the notch on the cam shaft. Then take a reading on the crank shaft. The pin on the crankshaft is used by the speed sensor and not for TDC alignment. For reference see Tming Chain replacement in the DIY articles.

Thank you for your responses.

when setting the 190e 8v to tdc, the "o" mark on the balancer is tdc of the crank, on the cam, look behind the gear, there is a small notch cast into the cam this must align with the valve cover surface of the head on the drivers side of the engine. If the cam timing has been altered it will effect the way the engine runs. a reterded setting will give poor bottom end but will extend the top end range the engine will rev.
hope this helps.:)
Joe

190e
 

and this car was raced,do you think it's possible that the cam timing was changed by the owner?poss to do by using diff holes on cam sprocket.and of course chain may be stretched but very short chain ,won't be much out of time with 150 or 200 kmls.

The TDC mark on the crank is a stamping that says O|T, the line between the 2 letters is the TDC mark.
Gilly