Carter BBD
Carburetor Alternatives
options for ditching
this problematic carb |
tech |
In
the last few years of the CJ series and the first few years
of the Wrangler YJ Jeep outfitted the 4.2L (258) 6 cylinders
with an electronic carburetor referred to as the BBD.
The Carter BBD is a two barrel carburetor that came in two
variations, one is computer controlled and has a stepper
motor on the back side. The computer controlled version was
used after 1981. Both have similar problems and
considering they haven't been "new" in approximately 20
years alternatives are sometimes the best option to regain
reliability and performance.
The BBD carb has a nasty
reputation, most anyone that has owned a Jeep with one of
these can relate. Sputtering, stalling, stalling at
every stop sign and only running off idle. Very
frustrating to deal with.
There are several popular
alternatives; electronic fuel injection systems by Mopar,
Howell, Holley and the home grown; carburetors by Weber and
Motorcraft. We will explore the positives and
negatives in all three types.
Fuel Injection
The benefits of fuel
injection are well documented. Reliability,
efficiency, and flexibility are some positive benefits to an
electronic fuel injection system. Some negatives of
these systems can be complexity and cost. Fuel
injection systems inject the fuel into the airflow by means
of a pressurized fuel system and electronic solenoid valves
commonly called injectors. The injectors pass the
correct amount of fuel as determined by the computer.
The computer often uses several sensors to calculate this
fuel mixture. Since the system is pressurized vapor
locking is practically impossible and there is no fuel bowls
to spill over in off-camber, incline, and decline driving
conditions.
There are two different
versions of fuel injection systems we will discuss here,
Multi-port and Throttle Body.
Multi-port systems use
injectors mounted in the intake manifold near the cylinder
head port. These systems are regarded as generally
more efficient than throttle body systems.
Throttle body systems simulate a carburetor and
typically can mount in place of a carburetor. These
systems have injectors mounted within the throttle body,
which pass the fuel into the throttle body to mix with the
air flow directly above the throttle plate.
Mopar
- Mopar makes an EFI system (shown to the right) that is
similar to the system found on the later model 4.0L engines
in the following models Cherokee, Grand Cherokee, Wrangler
YJ, Wrangler TJ. This system will require the largest
installation time and cost the most but will usually yield
the best performance gains and engine efficiency. This
isn't quite a fair comparison but a 4.2L carbureted 6 in a
typical 80's CJ made approximately 120HP, the 4.0L in the XJ
was rated at 190HP. $$$$
Howell
- The Howell throttle body system (shown left) includes
all components plus a new 4.3L Chevrolet throttle body to
convert a 2BBL CJ or Wrangler Jeep to EFI. This system
replaces the carburetor and manual fuel pump, the original
computer (if equipped) can be removed along with all the
wiring associated with it. A new electric fuel pump is
mounted on the frame in line of the fuel feed.
Matt's Jeep, an
84 CJ-7, has a Howell system installed with good results.
The power difference and engine behavior is very
distinguishable from the original set up. Matt no
longer experiences stalling or stumbling when climbing hills
on the trail. Howell offers an emission legal and
off-road only version. See
Howell
Engine Developments for more. $$$
Holley - We get many
questions about where to get this system. As far as we
can tell Holley no longer offers a Pro-Jection system for
the Jeep 6 cyl.
Home Grown - We have
seen several write ups around the net detailing a less
expensive conversion that gives you a throttle body system
for less. This swap typically involves the use of a
parts of TBI systems out of a vehicles equipped with a GM
4.3L V6, Typically a Chevy Blazer or GMC Jimmy. After
reading many of articles detailing these swaps they seem
do-able but are not for the impatient and/or technically
challenged. Perform at your own risk! $$
part 2 - Carburetor Options |