Chevrolet CHEVY VAN G10 SERIES Service Manual page 230

Fig. 4 i—Setting Point Opening
New points m ust be set to the larger opening as th e rubbing
block will wear dow n slightly w hile seating to the cam.
C o n tact points should be cleaned before adjusting if th ey have
been in service.
To adjust th e co n tact poin t opening:
1. T u rn or crank th e distribu tor shaft until the breaker arm
rubbing block is on th e high po int o f th e cam lo b e. This
will provide m axim um p oint opening.
2. Loosen th e contact sup po rt lock screw.
3. Use a screwdriver (Fig. 4i) to move th e point support to
ob tain a .019 " opening for new points and a .0 1 6 "
opening for used points.
4. Tighten th e co n tact su p po rt lock screw and recheck the
p o in t opening.
5. A fter checking and adjusting th e co n tact poin t opening
to specifications, the cam angle or dwell should be
checked w ith a dwell angle m eter if such equ ipm ent is
available (see Specifications for proper dwell angle). If
th e cam angle is less th a n th e specified m inim um , check
fo r defective or misaligned co n tact point (Fig. 5i) or
w orn distributor cam lobes. The variation in cam angle
LATERAL
MISALIGNMENT
N EVER BEND BREAKER LEVER
Fig. 5 i—A lignm ent o f Points
PROPER
LATERAL ALIGNMENT
readings betw een idle speed and 1750 engine rpm should
n o t exceed 3°. Excessive variation in this speed range
indicates wear in the distributor.
N O T E : Cam angle readings taken at speeds above
1750 engine rpm may prove unreliable on some cam
angle meters.
Eight Cylinder Engine Distributor
On the Vehicle
With the engine running at idle and operating tem peratures
norm alized, th e dwell is adjusted b y first raising th e window
provided in th e cap an d inserting a " H ex" ty p e w rench into
the adjusting screw head (Fig.
1. Preferred M ethod— T urn the adjusting screw until the
specified dwell angle is obtained as m easured in degrees
(29° to 31°, 30° preferred) by a dwell angle m eter.
2. A lternate M ethod— T urn adjusting screw in (clockwise)
until the engine begins to misfire, th en tu rn screw
tu rn in the opposite direction (counterclockw ise). This
will give th e approxim ate dwell angle required. (Use only
w hen m eter is n o t available.)
Off the Vehicle
1. D istributor Test M ethod:
a. With th e d istrib u to r m ounted on a distributor te st­
ing m achine, connect th e dwell m eter to the dis­
trib u to r prim ary lead.
b. T urn th e adjusting screw (Fig.
angle to 30 degrees.
2. Test Light M ethod:
a. W ith the d istrib u to r m ounted in a vise, connect a
testing lam p to the prim ary lead.
b. R o tate th e shaft until one o f th e circuit breaker
cam lobes is u n d er th e center o f th e rubbing block
o f th e breaker lever.
Fig. 6 i—Adjusting Dwell Angle
ENGINE ELEC TR IC A L 6Y -19
6
i).
6
i) to set the dwell
SCREW
1/2