BMW 5251 Service Manual page 317

Camshaft Timing chain1
-
- -
-
Using crankshaft center bolt, turn engine clockwise until
number one cylinder (right head) is in TDC overlap position,
as shown
(arrows).
NOTE-
Number one cylinder is at valve overlap when both the intale
and exhaust valves are starting to open.
<
Loosen accessible bolts (arrows) on right exhaust and
intake camshafts (cylinders 1-4) approximately
'I2
turn.
NOTE-
When loosening bolts on camshaft sprocket, counterhold
camshaft using an 27 mm open-end wrench. I f necessary.
machine wrench accordingly to prevent damage to head.
Repeat for accessible bolts of left exhaust and intake
camshafts (cylinders 5-8).
Using crankshaft center bolt, rotate engine one complete ro-
tation to TDC position. Lobes of camshafts for right cylinder
head (cylinders 1-4) should point to each other (arrows).
-
Loosen remaining intake and exhaust camshaft sprocltet
bolts approximately 'I2 turn.