Subaru Impreza 2002 Service Manual page 4136

(6) Ensure the camshaft and crankshaft sprock-
ets are positioned properly.
CAUTION:
• Intake and exhaust camshafts for this DOHC
engine can be independently rotated with tim-
ing belts removed. As can be seen from the fig-
ure, if intake and exhaust valves are lifted
simultaneously, their heads will interfere with
each other, resulting in bent valves.
(A) Intake camshaft
(B) Exhaust camshaft
• When the timing belts are not installed, four
camshafts are held at the "zero-lift" position,
where all cams on camshafts do not push in-
take and exhaust valves down. (Under this con-
dition, all valves remain unlifted.)
• When the camshafts are rotated to install tim-
ing belts, #2 intake and #4 exhaust cam of left-
hand camshafts are held to push their corre-
sponding valves down. (Under this condition,
these valves are held lifted.) Right-side cam-
shafts are held so that their cams do not push
valves down.
• Left-hand camshafts must be rotated from
the "zero-lift" position to the position where
timing belt is to be installed at as small an angle
as possible, in order to prevent mutual interfer-
ence of intake and exhaust valve heads.
TIMING BELT ASSEMBLY
(A)
(B)
EN1203
ME(STi)-51
• Do not allow the camshafts to rotate in the di-
rection shown in the figure as this causes both
intake and exhaust valves to lift simultaneous-
ly, resulting in interference with their heads.
MECHANICAL