Cessna 177 SERIES Service Manual page 171

After the engine has been placed in the correct firing c.
BENDIX D-2000 (DUAL) SERIES. The magneto
position, install and time the magneto to the engine must be installed with its timing marks carefully
in the following manner: aligned, with number one cylinder on its compression
1. Remove timing inspection plug from top of stroke and with the number one piston at its advanced
magneto. Turn magneto drive shaft in direction of firing position. Refer to paragraph 11-12 for the ad-
operating rotation until the applicable timing mark vanced firing position of number one piston. To lo-
on the distributor gear is approximately aligned with
cate the compression stroke of the number one cylin-
the mark on the distributor block. Depress impulse der, remove the lower spark plug from number 2, 3
coupling pawls on left magneto to rotate magneto and 4 cylinders. Remove the upper spark plug from
shaft.
number 1 cylinder. Place the thumb of one hand over
the spark plug hole of number one cylinder and rotate
NOTE crankshaft in the direction of normal rotation until
the compression stroke is indicated by positive pres-
The timing marks are for reference only.
sure inside the cylinder lifting the thumb off the spark
They should not be used to adjust contact plug hole. After the compression stroke is attained,
breaker point opening or to determine pro- locate number one piston at its advanced firing posi-
per timing of the magneto. (Refer to para- tion. Locating the advanced firing position of number
graph 11-60 for internal timing. ) one piston may be obtained by rotating the crankshaft
opposite to its normal direction of rotation until it is
2. Be sure magneto gasket (right magneto), mag- approximately 30 degrees before top dead center
neto adapter and gaskets (left magneto) are in place
(BTC) on the compression stroke of number one cyl-
and that engine is in the correct firing position, then
inder. Rotate crankshaft in a normal direction to
install magneto approximately at the angle noted dur-
align the timing mark on the front face of the starter
ing removal, tighten mounting nuts finger tight.
ring gear support with the drilled hole in the starter,
making sure the final motion of the ring gear is in the
NOTE
direction of normal rotation.
Be sure to keep timing marks in the magneto
NOTE
aligned as close as possible when installing
on the engine. An accurate top center indicator which
screws into a spark plug mounting hole,
3. Connect positive lead of the timing light (Ben-
and a pendulum pointer mounted on a
dix Part No. 11-9110 or equivalent) to the switch ter-
360-degree timing disc may also be used
minal (capacitor stud) of the magneto.
Secure the to locate the advanced firing position.
common lead of timing light to good ground. - The timing disc should be adapted to fit
4. Rotate propeller opposite to normal direction
over the end of the propeller spinner in
of rotation a few degrees (approximately 5 degrees)
such a manner that it may be rotated as
to close the magneto breaker contact points.
necessary. In all cases, it must be
definitely determined that the number
NOTE
one cylinder is at the correct firing posi-
tion and on the compression stroke, when
Do not rotate propeller backward enough to
the engine is turned in its normal direction
engage impulse coupling, or the propeller
of rotation.
will have to be rotated in the normal direc-
tion of rotation until impulse coupling re-
After the engine has been placed in the correct firing
leases on the left magneto, then again backed-
position, install the magneto to the engine in the fol-
up to a few degrees before the firing position. lowing manner:
1. Remove the timing window plug from the most
5. Slowly advance propeller (tap forward with
convenient side of the magneto housing.
minute movements as advanced firing position is ap-
2. Remove the rotor viewing location plug from
proached) in normal direction of rotation until timing the top center of the housing.
light indicates position at which contacts break.
The 3. Turn the rotating magnet drive shaft in the
contacts should break at the advanced firing position
normal direction of magneto rotation until the red
of number one cylinder.
Loosen mounting nuts slight-
painted tooth of the large distributor gear is centered
ly and rotate magneto case as required to cause the
in the timing hole (hole at each side of magneto).
contacts to break at the correct position.
Tighten
4. Also observe at this time that the built in
mounting nuts.
pointer just ahead of the rotor viewing window aligns
6. After tightening magneto mounting nuts, re-
with the L ("E" gap) mark on the rotor.
check timing. Make sure that both magnetos are set
5. Install the magneto-to-engine gasket on the
to fire at the same time. Remove timing equipment,
magneto flange.
install spark plugs and connect spark plug leads and
ignition switch leads.
[WARNING
Do not attach harness spark plug leads to
the spark plugs until all magneto-to-engine
timing procedures are completed and the
switch leads ("P" leads) are connected.
Change 2 11-25