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(Iinstallation
Guide)
Air/Fuel ratio Meter. How it
works?
An Air/Fuel Ratio monitor
will take the guesswork out of trying to tune your engine. An oxygen sensor,
located in the exhaust passage, produces a signal that is read by the A/F Meter.
The basic A/F Ratio Meter Kit is supplied with a standard single wire oxygen
sensor. An optional 3 wire heated sensor is available at added cost for those
requiring a faster warm up reaction time. The sensor must be hot, over 400
degrees before it will send a signal that the A/F Meter will respond to. You
will normally experience a delay in the function of the A/F Meter until the
oxygen sensor warms to operating temperatures.
Installation.
The
A/F meter should be cockpit mounted for easy visibility while driving your
vehicle down the road. The A/F Meter requires a 2 1/16“
mounting hole.
The oxygen sensor can be secured in the
exhaust system by first drilling a ¾“ hole and then welding in the supplied 18mm
threaded adapter. The oxygen sensor can then be threaded into the exhaust
system. The oxygen sensor is best installed in a location where it can monitor
all exhaust ports, upstream from the muffler and as close to the engine as
possible. An adapter pipe with an 18mm threaded adaptor welded into it already
is also available for quick and easay installation. An oxygen sensor can also be
used with a stock muffler system by welding the threaded adapter to the stock
muffler housing.
Single
Wire Oxygen Sensor Hook-up
The A/F Meter wire loom contains three
wires. The black wire goes to the terminal No.2, the red wire to
terminal No.4 and the green wire to terminal No.5. the
black wire on terminal No.2 at the meter is secured to the black wire
coming from the oxygen sensor. This takes care of hooking up the oxygen sensor.
Now back to the meter. Secure the red wire at terminal No.4 to an
OFF/ON 12 volt source such as the ignition switch. The green wire at terminal No.5
must be secured to a good clean chassis ground. The meter must be grounded to
complete the circuit. Meter lighting is activated by grounding one of the black
wires exiting terminal No.6 and connecting the other black wire to
the headlight switch.
Three
Wire Oxygen Sensor Hook-Up.
Same
as with a single wire kit, the A/Fmeter wire loom contains three wires. The
black wire goes to terminal No.2, the red wire to terminal No.4
and the green wire to terminal No.5. the black wire on terminal No.2
at the meter is secured to the black wire coming from the oxygen sensor. The
other two wires coming from the oxygen sensor are white, secure one of the wires
to a good clean chassis ground, it does not matter which wire you choose. Secure
the other wire to an OFF/ON 12 volt source such as the ignition switch. This
takes care of the hooking up of the oxygen sensor. Now back to the A/F Meter.
The red wire at terminal No.4 also is secured to an OFF/ON 12 volt
source. Then the green wire at terminal No.5 must be secured to a
good clean chassis ground. The meter must be grounded in order to complete the
circuit. Meter lighting is activated by grounding one of the two wires exiting
terminal No.6 and securing the other black wire to your vehicles
headlight switch.
Air/Fuel
Ratios.
The
ideal A/F ratio when using gasoline is 14.7:1. This is expressed in pounds
weight of air and fuel. An A/F ratio of 14.7:1 states that the engine is using
14 pounds of air for every pound of fuel. The optimal A/F ratio of 14.7:1 is
referred to as Stoichiometric. The goal is to approach and maintain
Stoichiometric or 14.7:1 A/F fuel ratio during idle and highway driving speeds.
This is seldom attained by carburetted engines.
The A/F ratio should richen to 12.1:1 or
even less during acceleration and top speed. The richer mixture is required
during this to aid in cooling the engine and to provide for increased power
output. Deceleration will show leaner A/F numbers such as 16.1:1 as the
throttles close and the engine burns off all available fuel.
Attempting to run excessively lean A/F
ratios can severely reduce engine life. High engine temperatures, backfire
through the carburettor, surging at highway speeds, and hesitation just off idle
are indications of lean A/F ratios. Sluggish performance, black smoke, and poor
economy are indications of a rich A/F ratio.
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