Chevrolet 70 Series 1970, Service Manual

Page: 389 / 841

GASOLINE ENGINES 6A-18
1 D riv e Housing 4 G asket
2 Housing Nut 5 A dapter Mounting Bolt
3 T a c h o m eter A dapter 6 Flyw heel Housing
tms
?
Figure 24—Tachometer Drive Installed
4. R em ove adapter a ssem b ly and gasket from
cylin d er block.
NOTE: If difficulty is experienced in rem ov­
ing the adapter a ssem b ly , try turning over engine
■with sta r te r to turn b olt (8, fig . 23) s o drive slo t
i s in v e r tic a l p osition to p erm it disengagem ent of
d rive shaft (7, fig . 23).
5. R eferrin g to figu re 23, rem ove co v er (5)
and in sp ect teeth on g e a r s (3 and 7). Clean o il
h o les in co v er.
INSTALLATION
1. L ubricate adapter p a rts with clean engine
o il and attach cover to housing with s c r e w s and
lock w a sh ers (6, fig. 23).
2. Check drive bolt (8, fig . 23) to make su re
it is firm ly tightened into threads in cam shaft. If
n e c e ssa r y , turn engine crankshaft to p osition drive
b olt s lo t in v e r tic a l p osition.
3. Align tongue on adapter shaft with drive
bolt slo t, then p la ce new gask et at cylinder block
and in sta ll adapter a ssem b ly . Connect flex ib le
d rive shaft housing to adapter (fig. 24).
4. Check tachom eter drive cable and housing
routing. T here m ust be no sharp bends or kinks
in the a ssem b ly . L ubricate tachom eter d rive cable
w ith approved lubricant (Type S T -640) o r equivalent.
HYDRAULIC GOVERNOR
TROUBLESHOOTING
To check fo r proper perform ance of hydraulic
governor units the follow ing procedure may be
used:
1 Shaft and Inner
Rotor Assembly
2 Pump Outlet
3 Pump Body
4 Governor Spinner
Shaft
5 Governor Spinner
Valve
6 Governor Spinner
Cover
7 Governor Pressure
Outlet
8 Shaft Thrust Washer
9 Valve Spring
10 Valve Adjusting Nut
11 Rotor Cover and
Spinner Housing
12 Drive Coupling
13 Outer Rotor
14 Inner Rotor
15 Oil Pump Pressure
Relief Valve Spring
Cap
Figure 25—Sectional View of O il Pump
and Governor Spinner Valve Assembly
1. Warm up engine to norm al operating tem p­
eratu re (approx. 180°F .).
2. In stall a te e in governor lin e at carburetor
and attach p r e ssu r e gauge. P rovide a tachom eter
to check engine sp eed .
3. Start engine and m om entarily run engine
at fu ll throttle to check n o-load rpm and o il p r e s ­
su r e on gauge. Chart below show s c o r r e ct full load
rpm and o il p r e ssu r e in governor lin e for each
type of engine:
Full-L oad
Gauge
Engine Model Governed Rpm O il P r e s s u r e
401M 3400 8 -1 0 p si
478M
3200
8 -1 0 p si
NOTE: N o-load sp eed s w ill be approxim ately
300 rpm higher than indicated fu ll-lo a d sp eed s.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL