Also check to see if the automatic advance
If the distributor was marked before removal, as
mechanism is working. This is done by keeping the
suggested, and the engine has not been cranked since
timing light aimed at the timing mark and gradually
the distributor was removed, installation is simple.
increasing the engine speed. If the advance mechanism
Align the rotor with the scribe mark on the distributor
is working, the timing mark should gradually move
housing, align the scribe marks on the housing and
away from the pointer. If the timing mark fails to move
engine block, and insert the distributor. As the
as you increase the engine speed or if it hesitates and
distributor drive gear meshes with the camshaft gear,
then suddenly jumps, the advance mechanism is not
the rotor turns a small amount. Pull the distributor up
functioning properly and must be repaired.
far enough to disengage the gear, and turn the rotor
back far enough to compensate for the turning and push
A quick simple check for correct coil polarity can
down again. When the housing is flush against the
be made by using an ordinary wooden pencil to prevent
block, the scribe lines will be aligned. Install the
the possibility of electrical shock. Remove any one of
hold-down bolt, clamp it, and lock the distributor in
the spark plug wires. Place the lead of the pencil
between the spark plug wire and the plug. Start the
engine and observe the spark (fig. 6-52). If it flares or
If the distributor does not bottom, do not attempt to
has a yellow tinge on the wire side, polarity is reversed.
force it down. The distributor shaft is not aligned with
If it flares or has a yellow tinge on the plug side,
the oil pump shaft slot or tang. Hold firm pressure on
polarity is correct. Most ignition coil terminals are
the distributor housing and crank the engine. When the
properly identified with a + or marking.
shafts line up, the distributor drops into place.
Because changing the gap changes the timing,
If the engine was cranked while the distributor was
point gap, or dwell, must be set before you attempt to
out, remove the No. 1 spark plug, and crank the engine
time the engine. If used points are to be reused, or the
until compression can be felt. Continue to turn the
gap setting is to be checked with the distributor
engine until the timing marks are lined up with the
installed, connect a dwell meter (following instrument
stationary pointer. (The timing marks are located on the
manufacturer's instructions). With the engine idling,
crankshaft vibration dampener or flywheel.) The
check the dwell. Compare the dwell reading with the
engine is now ready to fire the No. 1 cylinder.
manufacturer's specifications. If the dwell reading is
Align the housing-to-block scribe marks and turn
incorrect, adjust the point gap.
the rotor to align with the No. 1 spark plug tower on the
Remove the secondary coil lead from the
distributor cap. Note that the points are just starting to
distributor cap and ground it. Remove the distributor
open. Insert the distributor. Allow for this rotor
cap and rotor. With the dwell meter connected as
movement as the gears mesh. When the installation is
before, crank the engine and adjust the points as
correct, the distributor is fully bottomed, the points are
necessary (while cranking) to obtain the correct dwell.
just opening, and the rotor points to the No. 1 spark plug
Replace the rotor and distributor cap and reconnect the
tower on the distributor cap. This initial timing setting
coil secondary lead. Start the engine and check the
will suffice for starting the engine.
NOTE: Refer to the manufacturer's manual for
specific instructions on setting the timing.
To time the engine to manufacturer's specifications,
clean all the grease and dirt from the timing mark and
reference pointer. Draw a chalk line over the timing
mark to make it more visible. Connect the timing light
to the high-tension lead of the No. 1 spark plug and the
power leads to the power supply. Connect a tachometer
to the primary circuit of the distributor. Warm the
engine to normal operating temperature and adjust the
idle speed. Aim the timing light flashes at the timing
mark and reference pointer. If the timing mark and
pointer do not line up, loosen the distributor and turn it
in its mounting until the timing mark does align with
the pointer. Secure the distributor.
Figure 6-52.--One method of checking coil polarity.