Allis-Chalmers 400 Series - Adjustments; Carburetor and Governor Adjustments

Adjustments
ADJUSTMENTS
ALL 400 SERIES TRACTORS
1. CARBURETOR ADJUSTMENTS {Illustration A)
Lack of power and black sooty exhaust smoke
usually indicates that fuel mixture is too rich. An
"overrich" mixture may also be caused by a clogged
air cleaner - check this before readjusting carburetor.
Fuel mixture may be too lean if engine "skips" or
backfires at high speed.
Main Fuel Adjustment: For preliminary setting,
turn MAIN FUEL screw in clockwise direction'unti I
it bottoms lightly (do not force) then back out
two {2} turns. With engine thoroughly warmed
up and running at full throttle and full load, turn
MAIN FUEL screw in until engine stows down
(lean setting) then turn screw out until engines
regains speed and then starts to stow down (overrich
setting). Turn screw back in until it is positioned
halfway between lean and overrich settings - when
properly adjusted engine will accelerate smoothly
and operate with steady governor action.
Idle Adjustment: Rough idle is usually caused by
the idle speed being set too low. Turn IDLE SPEED
screw in (clockwise direction) to increase speed. If
engine still idles poorly after speed is increased, stop
engine and turn IDLE FUEL screw all the way in
(clockwise) until it bottoms tightly (do not force
screw), then back out 1-1/4 turns. Restart engine
and check idle - turn needle in or out (1/4 turn at
a time) until smoothest idle is achieved.
Idle speed should be 1600 to 1800 RPM.
2. GOVERNOR ADJUSTMENT (Illustration B)
The governor functions to maintain engine speed
under changing load conditions and also acts as a
speed limiting device. Governors are set in the
factory and further adjustments should not be
required unless linkage works loose or becomes
disconnected. Readjustment should be made if
engine surges with changing load or if speed drops
considerably when a normal load is applied.
Initial Adjustment: With engine stopped, loosen
(do not remove) arm retaining nut securing governor
arm to governor cross shaft. Grasp end of cross
shaft with pliers and turn shaft as far as possible in
counter-clockwise direction - tab on shaft will stop
internally against governor gear mechanism. Hold
shaft in this position, pull governor arm all the way
away from carburetor then retighten arm retaining
nut to complete initial adjustment.
Throttle Wire Installation: If throttle wire has been
disconnected, move throttle control handle to full
throttle position. Insert throttle wire into hole in
high speed bracket swivel. With high speed bracket
against high speed stop, tighten swivel screw on
throttle wire.
Speed Adjustment: Maximum allowable speed for
these engines is3600 RPM. This speed must not be
exceeded. If overspeed condition is suspected,
check RPM's with hand tachometer and readjust as
follows:
With variable speed type arrangement as
shown in illustration, loosen capscrew and
move high speed stop bracket until correct
maximum speed is attained - retighten cap¬
screw to lock bracket in new position.
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