GMC 1977 motorhome User Manual

Onan Motor Generator
Carburetor Adjustment Points
6 . Rotate the engine clockwise (facing fly-
wheel) by hand until mark on gear cover aligns
with mark on flywheel . On the 6KW Model,
rotate it to the 21 ° BTDC mark . Turn another
1 /a
turn (90 0 ) to ensure points are fully open .
7 . Using an allen wrench
inserted in screw
(D) on
the right side of the points, turn points
until gap measures
.016 with a flat thickness
gauge (be
sure gauge is clean) . Replace cover
and
screw on breaker box .
CARBURETOR
The carburetor has a main fuel (power) ad-
justment and an idle fuel adjustment . The main
adjustment affects operation under heavy load
conditions . Idle adjustment affects operation un-
der light or no-load conditions . Under normal
circumstances, factory
carburetor adjustments
should not
be disturbed .
On the 6KW Model the normal settings are
1 5 /8 -turn open for main fuel adjustment and
one turn open for idle fuel adjustment .
IMPORTANT : Forcing the needle against its
seat will damage it . The needle does not com-
pletely shut off fuel when turned fully in .
Before final adjustment, allow the engine to
warm up . Make the idle adjustment under no
load .
Open
the main fuel adjustment until the
engine
runs smooth under acceleration with no
load . Slightly more fuel may be needed
(open
10 3
about 1 /4 -turn further) when
sudden load is
applied or if operating in very cold weather
. Set
the throttle stop screw
with no load connected
and while running
at a low speed setting . Turn
the
screw to give approximately 1/32-inch be-
tween the throttle stop screw and throttle lever .
If the engine develops a "hunting" condition
(alternate increase and
decrease of
engine speed),
try correcting by opening the main fuel adjust-
ment a little more . Do not open more than 1 /z
turn beyond the maximum power point .
There is no routine maintenance required on
the standard toilet . If a problem occurs, check
and make the appropriate correction .
1 . PROBLEM :
Water keeps running into the
bowl
.
CAUSE :
The blade in the bottom of the bowl is not
closing completely, which in turn keeps
the water control valve partially open
.
The groove into which the blade seats
when completely closed is clogged with
foreign material . Odors could also leak up
into vehicle .
SOLUTION :
Depress foot pedal to expose blade seal .
Insert the end of a coat hanger or similar
object into the seating groove and remove
the foreign
material . Avoid damaging
the
rubber seal while cleaning .
2 . PROBLEM :
STANDARD TOILET
Toilet leaks . There is water on the floor .
Specify the symptom . Determine if water
is leaking from
a . The vacuum breaker .
b . The water control valve .
c . Bowl to mechanism seal (if
this is the
problem,
the water would not stay in
the bowl) .
d . Closet flange base seal .

GMC 1977 motorhome Specifications

General

Manufacturer	GMC
Model Year	1977
Transmission	3-speed automatic
Fuel Type	Gasoline
Drive Type	Front-wheel drive
Wheelbase	140 inches
Width	96 inches
Height	108 inches
Engine	455 cu in (7.5 L) V8
Length	23 ft (7.0 m)
Weight	10, 500 lbs
Fuel Capacity	25 gallons
Sleeping Capacity	4 to 6 people