in the engine and will also affect the tester opera-
PULSE GEN for electronic pulse generator type
distributors. Place the selector switch in either the
tion. Perform this test as follows;
a. With motor switch positioned for the proper di-
tion as required.
rection of rotation for the distributor mounted and
the speed set for zero rpm, clip the distributor
4-14. Start the tester in the proper direction of
DWELL lead to the distributor body or ground it to
rotation and adjust the speed to approximately 1000
rpm. Rotate the degree ring of tester until the zero
b. Adjust the DWELL CALIBRATE control to
on ring is aligned with one of the arrow flashes.
position the meter pointer at the highest graduation
Observe the relative position of all arrow flashes.
The arrow flashes should be evenly spaced around
c. Connect the DWELL lead to the distributor ter-
the degree ring within plus or minus 1 degree. The
spacing is as follows:
d. Rotate the distributor shaft by hand until the
4 lobe cams 90
points are closed. The dwell meter pointer will re-
6 lobe cams 60
turn to the set position unless resistance is present
8 lobe cams 45
in the distributor. If the pointer droop is in excess of
7% the distributor resistance is excessive. The
4-15. BREAKER POINT ALIGNMENT
source of the excessive resistance may be isolated
(Not applicable to pulse generators)
by making step by step checks with the DWELL
test lead through the distributor from the terminal
4-16. Observe the slight arc appearing between
to the body. On distributors with two sets of points,
the breaker points. If the points are properly align-
each set must be checked independently while the
ed, the arcing will appear in the center of the points
other is blocked open. As the test lead is being
when viewed from above and from the side, Reduce
moved, if the meter reading indicates less resistance
tester speed to 200 rpm.
than the previous step, it is a measure of the resist-
ance between the present point of contact and the
4-17. BREAKER POINT DWELL
e. With points closed, adjust DWELL CALI-
4-18. Connect DWELL test lead to the distributor.
BRATE control to the full scale mark.
Observe the dwell meter and if necessary adjust the
point spacing until the dwell meter indicates the re-
4-8. BREAKER POINT SPRING TENSION
quired degree of dwell. On distributors equipped
with dual points it will be necessary to adjust each
set of points individually. The set not being tested
4-9. Proper tension of the breaker point spring is
may be blocked open using a piece of fibre or other
an essential to normal operating life and efficiency
insulator between the contacts. If the proper dwell
of the distributor throughout its speed range. Ex-
angle can not be obtained check the following possi-
cessive spring tension will cause rapid wear of the
ble sources of trouble;
cam follower block, while insufficient tension will
a. Improper spring tension or sticky pivot.
cause high speed bouncing of the points and conse-
b. Wrong point set installed.
c. Bent shaft, causing point opening to vary on
4-10. Place the end of the spring tension tester
each cam lobe.
near the contact of the movable point and slowly
d. Worn cam lobes or defective cam causing a dif-
pull at right angles to the point lever. Note the
ferent gap at each lobe. Check the gap at each lobe.
reading on the tension tester at the instant the
e. Points floating or not following the cam at high
points separate. The dwell meter may be used to in-
dicate the point of separation precisely.
f. Excessive resistance causing a false dwell read-
4-11. Alternately opening and closing of the points
4-19. BREAKER POINT DWELL VARIATION
using the spring tension tester will show up pivot
friction which can be caused by lack of lubrication or
4-20. While watching the dwell meter, vary the
speed from 200 to 1750 rpm. A dwell variation in ex-
cess of 2 indicates worn distributor shaft or bush-
ings. Reduce speed to 200 rpm.
4-13. Connect distributor lead to the distributor.
4-21. At distributor speeds up to approximately
Use the lead marked STD DIST for standard
1000 rpm the stroboscope will display the point of
breaker point ignition and use the test lead marked