Advertisement
9-14
PART
9-2
DUAL ADVANCE DISTRIBUTORS
BOSCH
Section
1
Description and Operation
2 In-Car Adjustments and Repairs
6 and 8 Cyl. Models
Page
9-14
Section
Removal
Installation
__
--
_
Breaker Point and Condenser Replacement
9-14
9-14
4 Major Repair Operations •
Bench Disassembly
~-
Bench Assembly
Pap
9-15
9-15
9-15
9-15
9-17
3 Removal and Installation
9-15
D
DESCRIPTION AND OPERATION
The dual advance distributor has
two independently operated spark
advance systems. A centrifugal ad-
vance mechanism is located below
the stationary sub-plate assembly
and a vacuum operated spark control
diaphragm is located on the side ·of
the distributor base.
As speed increases, the centrifugal
weights cause the cam to advance or
move ahead with respect to tlie dis-
tributor drive shaft. The rate of ad-
vance is controlled by calibrated
springs.
ADVANCE
ADJUSTING BRACKET
WEIGHT
LUBRICATING WICK
STOP
PLATE
The vacuum advance mechanism
has a spring loaded diaphragm which
is connected to the breaker plate. The
spring loaded side of the diaphragm
is
airtight and is connected through
a vacuum line to the carburettor
throttle bore. When the throttle plate
opens, the distributor vacuum passage
is exposed to manifold vacuum, which
causes the diaphragm to move against
the tension of the spring. This causes
the movable breaker plate to rotate on
the stationary
sub-plate.
The breaker
point rubbing block then moves
against distributor rotation and ad-
vances the spark
timing.
FIG. 1-Typical Centrifugal Advance Mechanism
EJ
IN CAR ADJUSTMENTS AND REPAIRS
BREAKER POINT AND
CONDENSER REPLACEMENT
REMOVAL
1. Unfasten spring clips holding
distributor cap in place and remove
cap.
2. Carefully lift rotor from the
cam spindle.
3. Remove contact breaker lead
from primary terminal connector.
4. Remove spacing shims (if any)
from contact breaker point pin.
5. Remove screw securing contact
breaker assembly to breaker plate
and lift off contact breaker assembly.
Care must be taken to prevent spac-
ing shims from under moving contact
from being dislodged and dropped in-
to the distributor body. The contact
breaker assembly may be separated
by depressing the moving
contact
spring blade until the
terminal
block
is clear of the stationary
point.
INSTALLATION
1. Instal stationary
contact
and
attaching
screw.
·2. Instal contact height
aligning
shims on pivot post and
instal contact
breaker
arm.
Advertisement
