Most magazine adds would have you believe that by
simply replacing your stock carburetor with a "performance" Holley or
Edelbrock carburetor will result in huge horsepower gains and turn your stock
engine into a fire breathing street machine. Now it is true that stock carburetors
are a compromise between economy, drivability, and performance, but in
most cases that "bolt on" carb upgrade will actually decrease
power along with even a larger reduction in gas mileage, not to mention
hesitations, hard starting, and great frustration. But by simply
spending a little time and logical effort you can get the results those
magazine adds promise. There has been a lot of information and books
written on the Holley Carburetor but it is very difficult to find anything
on tuning the Edelbrock (Carter AFB) carburetor,
Although Edelbrock claims the "Your Edelbrock
Performer Series carburetor was calibrated .... in most applications you
will not need to recalibrate your carburetor."
I would disagree and highly recommend that you take the time to
thoroughly read this information and recalibrate your carb, you will be
astonished by the performance difference. The manual that comes
with the Edelbrock Performer Series Carburetor is excellent, much of the
initial information provided is from this manual, but more can be gained
by taking the tuning a step further.
Before
you even begin jetting it is critical that the carburetor is the correct
size for the engine you are installing it on. The two biggest
mistakes made are; installing a carburetor that is too large, bigger is
NOT better; and then running too rich a mixture. Carburetors are relatively
simple fuel/air mixers that rely on airspeed to create a pressure drop
to "draw" and mix the fuel into the air stream, a
carburetor that is too large can result in an air speed too low so that
the fuel is not meters correctly and remains as droplets that do not mix
or atomize with the air. The end result is an engine with lower
power and poor throttle response. A carburetor that is too small
will restrict airflow limiting engine power and speed at higher rpm's.
The
Edelbrock Performer series carburetor is a redesigned and refined
version of the Carter AFB. Fuel metering is by means of main jets and
stepped metering rods, this combination allows for fast and easy
calibrations that can be tailored precisely to your engine.
The following consists of 3 sections; Section 1,
Theory of Operation which will provide an
understanding of how a carburetor works, and the functions of the various
circuits. Section
2, Tuning Procedures will take you through the Edelbrock step-by-step procedure
which will enable you to achieve a relatively close calibration for your
particular engine set-up, this is as far as most people go. Section 3 Power
Tuning Procedures will
outline the method for optimizing the carburetor's potential, taking the
tuning procedure that one step further.
