NOTE : BMW does not rely on timing marks for precise engine timing. Correct basic engine timing is achieved when the camshafts and crankshaft have been locked into exact alignment with special tools prior to timing chain installation.
CAUTION! : Incorrect setting/installation without the use of special tools could damage or break the camshafts. Valves could also be bent through contact with the piston crowns. Always note installation instructions and use specified special tools, procedures, and sequences.
You can try and follow these instructions on how to set the timing, but you are playing with fire if you are incorrect.
Crank over engine in direction of rotation until peaks of intake and exhaust cams in cylinder no. 1 face each other. Arrows on timing chain sprockets face up.
Installation: Hold crankshaft in TDC position with Special Tool 11 2 300.
WARNING: Remove special tool before operating the engine.
Installation: Align camshaft and hold it with Special Tool 11 3 240.
Camshafts can be turned on the hexagon with a 27 mm wrench.
WARNING: Don't damage the bearing plate - machine sides of open end wrench as shown if necessary.
CAUTION: If the camshaft position has to be corrected enough that there is valve movement in cylinder no. 1 and 4, first turn the crankshaft approx. 90 away from TDC pesttion in the engine's direction of rotation and return it only after turning the camshaft. In this manner contact between valves and the piston will be avoided.
Install and unlock chain tensioner after assembling.
Press chain tensioner against the timing chain.
Recheck the camshaft adjustment.