Exhaust Gas Recirculation Valve (EGR) takes a portion of the already burned
exhaust gases and injects them into the fresh Air/Fuel mix of the intake.
This in turn will decrease the "burn time" of the mix when it gets into the
combustion chamber, which in turn lowers the temperature of the exhaust.
By lowering the exhaust temp, the Oxides of nitrogen (NOX) is decreased.
This is the pollutant the EGR takes care of, and in 75, the unleaded fuel
and catalytic convertor were also used to decrease this and other
pollutants. AMC intro'd the EGR valve in 1973, though other companies had
them sooner. (Some companies didn't use a specific valve, but a passageway
instead). The smog pump was intro'd in almost all car lines in 1966. It
injected fresh air into the exhaust manifold to "reburn" the unburned fuel
that left the engine. Unburned fuel produces Hydrocarbons (HO) and is
usually checked at the tailpipe. (Some gas stations now have pumps that
seal against the filler when pumping gas-this also is to reduce HO. And
the charcoal cannister attached to the car is actually for the fuel tank
and carb float bowl vents, and used to reduce HO). The pump uses about 5
HP, but does not effect the performance of the engine as the burning takes
place outside the combustion chamber, in the exhaust. The pump is made by
Saginaw, a division of GM, and is found on a number of cars from the
60s-80s-almost all the same pump.
There are tubes attached to the exhaust manifolds to inject the air into
the engine through nozzles. For AMC, 66-70 are one design, 71-72 used a 4
tube drivers side and 4 tube passenger side. In 1973, the drivers side was
changed to 3 tubes. These may still be available from an old AMC (Eagle)
dealership, as they were used right up to 1988 on the Grand Wagoneers.
There is a check valve on top of the tubes to prevent the hot exhaust gases
from going into the pump. Unfortunately, they often failed. This is why
the pumps are often seized. There is also a cannister in the system, often
called a gulp valve or anti backfire valve. This vents the air from the
pump into the atmosphere instead of the manifolds during rapid
decelleration. It is needed due to the high amount of unburned fuel
leaving the engine at this time. If you injected fresh air into it at this
time, you would blow the exhaust manifolds off the car. 1966-1972 AMCs
used one design, 73 up used another-I believe the same one Ford used so
74-6 Bricklins should be the same, except for the manifold tubes. Again,
the best source for parts is a Grand Wagoneer.
A few other notes-the smog pumps were originally used on standard shift
cars only, as the car spewed a lot of smoke when the engine was
freewheeling due to the depressed clutch (just look at the smoke from an 18
wheeler when it shifts). As a result, automatic equipped cars did not have
the manifold tubes. I have replaced a number of these manifolds on AMXs
over the years to clean up the appearance of the broken or rusted tubes. I
also removed the EGR valve by replacing the intake manifold-it would have
to come off a 1970 or later AMC as the bolt holes are not the same as the
66-69 V8, though they look the same. If the car is kept tuned, you will
find this engine is one of the least polluters and will easily pass the
tests.
If your smog pump is seized, you can take it apart and break the "wafer
boards" that are used to circulate the air. You will end up with just a
turning shaft not doing anything, but at least it is on the car. The
correct smog equipment is also in demand by owners of AMXs and Javelins, so
hold on to it.
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