CARBURETORS: ZENITH
ZENITH POINTERS ON GOOD CARBURETION AND HARD STARTING
Factors Which Assist Good Carburetion
Ignition spark plug should be set with at least .025" gap. 1\lany are now
using .031" gap, and some even use .035". (See also page 1302 for discussion
on spark plug gap.)
Interrupter points should be clean and properly set according to manufacturers'
specifications. Usually about .015" to .020" gap when the points are
wide open, with spark lever retarded when TC mark on flywheel is in line with
pointer is the approximate average interruptor setting and timing.
Leaky carburetors are in many instances caused by dirt under the float needle
valve.
It can usually be removed by alternately raising and lowering it. from its seat,
at the same time giving it a twisting motion with the fingers.
If the dirt is loose or only slightly embedded this will wash it away.
In aggravated cases, hold the needle valve firmly on the scat with the fingers
and, with a light tool, gently tap the top of the valve.
The bearing points of the needle valve and of the needle valve seat are highly
polished at the factory. Therefore, do not try to regrind the seat as this procedure
is in most cases productive of bad results.
If necessary to fit a new needle valve, or needle valve seat, replace both of
them with new parts. Never replace one and leave the other in the carburetor.
When any parts of the needle valve or float mechanism are replaced use a level
test gauge to adjust the fuel level.
If the float is leaky and contains gasoline, the additional weight will cause
a high level and flooding condition.
If the needle valve counterweights are worn badly, the float can raise
too high and will result in flooding. Turn them over, or replace with new weights.
Never raise or lower the fuel level for the purpose of leaning or enriching the
mixture.
If, after stopping the engine, a bit of fuel leaks from the carburetor, do not
be alarmed. This is only the fuel drawn up into the carburetor barrel and manifold
which, due to insufficient suction, does not get to the cylinders. When the engine
is stopped, releasing the suction, this fuel naturally drops and is soon drained
off through the small hole in the bottom of the carburetor provided for that
purpose.
This is more noticeable in cold than in hot weather. Always close the throttle
before shutting off the engine. This will usually eliminate this condition, and
in other cases reduce the loss to a minimum.
Hard Starting
See if you have fuel in the carburetor. This can be determined by removing the
dust cap and pressing down on the needle valve. If the valve cannot be de-pressed
by the finger there is fuel in the carburetor.
In the case of F-type carburetors, remove the float cover to see if fuel is in
the bowl.
See if you have a good spark at the spark plugs.
Have throttle lever only slightly open, so as to get full effect of the suction
on the idling jet and well.
See if strangler valve closes completely. Check manifold and connections for
air leaks.
Be certain starter is turning engine over with sufficient speed to lift fuel
to the cylinders (at least 100 r.p.m.).
Check for dirt or water in carburetor and particularly in idling jet.
In cold weather it sometimes happens that water accumulates in the carburetor
or fuel line and freezes, thus shutting off the flow of fuel.
Weak compression, riding valves, faulty adjustment of spark plugs and breaker
points will make starting hard.
Do not flood the engine with gas. If you do, release the strangler, open the
throttle half way and turn the engine over. This will dilute the mixture in the
cylinders to a point where it will ignite.
Too much gasoline consumption may result from one or several causes:
Check carburetor adjustment.
Check ignition adjustment.
Check brake adjustment.
Check fuel connections and carburetor for leaks. Check hot air tubing connections.
Check strangler adjustment.
Check condition and amount of oil in engine, transmission, rear axle, wheel bearings,
universal joints, etc.
ZENITH GASOLINE FLOAT LEVEL ADJUSTMENT
The dimensions, given in inches, are the measurement from the top of the machined
surface of the float bowl to the fuel itself on the following models and sizes
of carburetors:
Models CV14, CV20, CV20C, CV20L, CV20M, i,"; model CV22F, g4"; models
IA, 1.5, L6, L6T, L7, L7T, L8, 1,5"; models 034, 04, 05, Q4C, Q5C, 41";
Model Q6C, l h"; model T3, a4"; models T3 „ T4, T4X, T4XF, T4F,
T5F, T5XF, 44”; models S4, S4BF, 1J4, 44"; models S5, S6, U5, U6,
4)"; models USF, U5FL, U5FW, U5FR, 1,z"; models UL5, UL6,
Models SV5, SV6, SV7, SV8, 1,4 "; models ST4, ST4B, ST4T, ST5, a4";
model T5T, a4"; models T4DS, T4XD, 41"; model US52, ill".
Models HF2 4K, HF3K, HF3KC, HF3A-B, a4"; models HF3 4, FF3 4F, HF4A, HF4B,
HF5H, a4"; models HP4, HP5, 4i"; models HP6A, IIP6B, 1A:,"; models
HR20, HR20AM, HR26A, HT3, l"; model HT4F, a4"; models HT5HF, HU4A,
Models 04D, 05D, 06D, 07D, 08D, 1"; models ER20F, ER26A, 444"; model
V4B-SV4, a$".
Model 48DC, l"; models SLGS, SL6L, SL7R, SLRS, 1,5".
To make adjustment, it is necessary to unsolder the needle-valve collar and move
it up or down on the float needle valve and then resolder; moving collar away
from pointed end slightly lowers the level and toward pointed end raises the
level. Models ST and SV can be adjusted by bending the float arm, but this is
not considered good practice. All Zenith carburetors bear a scratch-awl mark
on the side of float chamber which indicates the gasoline level.
Level test gauge: On all models except ST and SV it is necessary to use a level
test gauge to set the fuel level properly, be-cause when the float cover is removed
the gasoline level drops (not. on ST and SV models). Three gauges are required
to fit all makes of Zenith carburetors (one each for models L, 0, and T) and
the price is $2.50 each. (Can be obtained of Zenith-Detroit Corp., Detroit, Mich.,
or at Zenith service stations.)
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