f. Start both rotor gears straight on the rotor shafts
with the right-hand helix gear on the right-hand
helix rotor and the left-hand helix gear on the
left-hand helix rotor, and the omitted serrations
in the gears in line with the omitted serrations on
the rotor shafts.
g. Thread an installer screw J 6270-8 in the end of
each rotor shaft until it bottoms. Place gear
installer J 6270-7 over the installer screw and
against the right-hand helix gear and gear
installer J 6270-6 over the installer screw and
against the left-hand helix gear. Then, thread a
h. Place a clean folded cloth between the lobes of
the rotors, to prevent the rotors from turning.
Then, turn the nuts on the installer screws
clockwise as shown in Fig. 15 and draw the two
Fig. 15 - Installing Rotor Gears on Rotor Shafts for
gears into position at the same time, tight
Preliminary Check of Clearances using Tool J 6270-
against the shims and bearing inner races.
6, 7 and 8.
i. Remove the rotor timing gear installers from the
l. Bend one of the tangs of each lock washer over
against the head of the gear retaining bolt.
Remove the cloth from between the blower
j. Place a lock washer (16) and the gear retaining
washer (19) on one of the gear retaining bolts
(Fig. 7). Thread the bolt into the right-hand
helix rotor shaft, and guide the lugs on the
Timing Blower Rotors
retaining washer in the slots in the gear hub.
After the blower rotors and timing gears are installed,
the blower rotors must be timed.
Bend one of the tangs on the lock washer over
into the slot of the retaining washer. Tighten the
The blower rotors, when properly positioned in the
gear retaining bolt to 55-65 lb-ft (75-88 Nm)
housing, run with a slight clearance between the lobes.
This clearance may be varied by moving one of the
k. Place a lock washer (16) and the fuel pump
helical gears in or out on the shaft relative to the other
drive coupling disc (18) on the remaining gear
retaining bolt (Fig. 7). Thread the bolt into the
left hand helix rotor shaft and guide the lugs on
If the right-hand helix gear is moved out, the right-hand
the disc in the slots in the gear hub. Then bend
helix rotor will turn counterclockwise when viewed from
one of the tangs on the lock washer over into
the gear end. If the left-hand helix gear is moved out,
the slot in the disc. Tighten the gear retaining
the left-hand helix rotor will turn clockwise when viewed
bolt to 55-65 lb-ft (75-88 Nm) torque.
from the gear end. This positioning of the gear, to
obtain the proper clearance between the rotor lobes, is
known as blower timing.
Fig. 16 - Measuring "CC" and "C" Clearances Between Blower Rotor Lobes.