Chevrolet 10 1971 Series Chassis Service Manual page 270

ENGINE-ELECTRICAL 6Y-20
6. Remove vacuum advance mechanism retaining screws,
remove the vacuum advance assembly.
7. Remove the spring retainer, remove the breaker plate
assembly from the distributor housing. Remove the
contact point and condenser from the breaker plate.
Remove the felt washer and plastic seal located
beneath the breaker plate.
Cleaning and Inspection
1. Wash all parts in cleaning solvent except cap, rotor,
condenser, breaker plate assembly and vacuum con­
trol unit. Degreasing compounds may damage insula­
tion of these parts or saturate the lubricating felt
in the case of the breaker plate assembly.
2. Inspect the breaker plate assembly for damage or
wear and replace if necessary.
3. Inspect the shaft for wear and check its fit in the
bushings in the distributor body. If the shaft or
bushings are worn, the parts should be replaced.
4. Mount the shaft in "V " blocks and check the shaft
alignment with a dial gauge. The run-out should not
exceed .002" .
5. Inspect the advance weights for wear or burrs and
free fit on their pivot pins.
6. Inspect the cam for wear or roughness. Then check
its fit on the end of the shaft. It should be absolutely
free without any roughness.
7. Inspect the condition of the distributor points. Dirty
points should be cleaned and badly pitted points should
be replaced. (See Distributor Contact Points.)
8. Test the condenser for series resistance, microfarad
capacity (.18 to .23) and leakage or breakdown,
following the instructions given by the manufacturer
of the test equipment used.
9. Inspect the distributor cap and spark plug wires for
damage and replace if necessary.
Assembly
Six Cylinder Engine (Fig. 9i)
1. Replace cam assembly to mainshaft.
Lubricate top end of shaft with Delco cam
NOTE:
and ball bearing grease or equivalent prior to
replacing.
2. Install governor weights on their pivot pins, replace
weight springs. Install weight cover and stop plate.
3. Lubricate mainshaft and install it in distributor
housing.
4. Install distributor driven gear to mainshaft and insert
retaining roll pin. Check to see that shaft turns
freely.
5. Install breaker plate assembly in the distributor body
and attach retaining screws.
6. Attach condenser and contact point set in proper loca­
tion with appropriate attaching screws.
Contact point set pilot must engage match­
NOTE:
ing hole in breaker plate. Connect primary and
condenser leads to contact set quick-disconnect
terminal.
7. Attach vacuum control assembly to distributor hous­
ing.
8. Check and adjust contact point opening and alignment.
(See setting and alignment of points.)
9. Check breaker lever spring tension which should be
19-23 ounces. (See contact point replacement.)
10. Install dust shield and rotor.
V-8 Engines— (Fig. lOi)
1. a. Fill housing lubricating cavity with proper com­
pound, press in new plastic seal and install felt
washer.
b. Replace the vacuum advance unit.
c. Install the breaker plate in housing and the spring
retainer on the upper bushing.
Spring should seat on the "flat" ma­
NOTE:
chined on one side of the mainshaft.
2. Lubricate and slide weight cam over mainshaft and
install weights and spring (fig. lli).
3. Insert mainshaft into housing, indexing it with drive
gear and washers.
4. Slide distributor drive gear shims and gear over
shaft and install new pin. Tap new pin through gear
mainshaft. Check shaft for free rotation. On heavy
duty models, install shock mounting assembly.
5. Install contact point set and condenser to breaker
plate. Connect leads as shown in Figure li.
Contact point spring tension is factory-
NOTE:
set above specifications to assure ease of final
adjustment. Correct tension is 19-23 oz.
6. Install rotor to cam assembly, indexing round and
square pilot holes.
Installation— Engine Not Disturbed (All Models)
1. Turn the rotor about 1/8 turn in a clockwise direction
past the mark previously placed on the distributor
housing to locate rotor.
2. Push the distributor down into position in the block
with the housing in a normal "installed" position
(figs. 12i, 14i and 15i).
It may be necessary to move rotor
NOTE:
slightly to start gear into mesh with camshaft
gear, but rotor should line up with the mark
when distributor is down in place.
3. Tighten the distributor clamp bolt snugly and connect
vacuum line. Connect primary wire to coil terminal
and install cap. Also install spark plug and high
tension wires if removed.
It is important that the spark plug wires
NOTE:
be installed in their proper location in the sup­
ports (figs. 14i and 15i).
4. Time ignition as previously described under Tune-Up
in Section 6.
Installation— Engine Disturbed (All Models)
1. Locate No. 1 piston in firing position by either of two
methods described below.
a. Remove No. 1 spark plug and, with finger on plug
hole, crank engine until compression is felt in the
No. 1 cylinder. Continue cranking until timing
mark on crankshaft pulley lines up with timing
tab attached to engine front cover.
b. Remove rocker cover (left bank V-8 engines) and
crank engine until No. 1 intake valve closes and
continue to cranks slowly about 1/3 turn until
timing mark on pulley lines up with timing tab.
2. Position distributor to opening block in normal in­
installed attitude (figs. 12i, 14i and 15i), noting posi­
tion of vacuum control unit.
3. Position rotor to point toward front of engine (with
distributor housing held in installed attitude), then
10-30 CHEVROLET TRUCK SERVICE MANUAL