Fiat 124 Spider - Carburetors

FIAT 124 Spider
Engine Maintenance + Modification
87
11.5 Carburetors
We discussed the stock carburetors earlier in this book. The carburetors were
reasonably good matches to the engine size; however, a general rule is that the cars
were always slightly under-carbureted. Every time an owner installs a DHSA2 on a car
previously fitted with the DHSA1 the performance increases. Simply put, the DHSA2
allows more air into the motor. Every Spider 2000 owner who replaced the ADHA and
manifold with a DFEV, ADF, or ADFA has felt his car spring to life. This section deals
with good swaps and good new carburetors to install on your car.
Most folks who are considering a carburetor swap will likely stay away from the
pneumatic carburetors. Truth be told they aren’t as fun to drive; the secondary always
lags behind the first regardless of how hard you press the gas pedal. They were
designed to deliver the secondary fuel at an “appropriate” time, which is fine for fuel
economy and emissions, but not so much for overall driving fun. The pneumatic
carburetors are harder to find parts for and their unpopularity in modern applications
makes parts availability scarcer every day.
Mechanical carburetor swaps are very easy on the Spiders. The easiest and most
popular is done by owners of the Spider 2000. The Spider 2000 owner can buy an 1756
intake manifold and the Weber 32ADFA carburetor and install them in the same locations
as the old carburetor. Plug in the fuel lines, distributor vacuum pulse line, cold start
hoses, and linkages, and get an immediate performance increase. The two carburetors
are externally near identical, meaning that the hoses and other pieces line up nicely. The
real gain for the Spider 1756 and 2000 owner is from the other Weber ADF, the 34 ADF.
Available new from most parts vendors the 34 is a very large and powerful carburetor
with no unnecessary components. It has connections for the distributor vacuum and
vapor recovery; otherwise it is just a fine Weber carburetor that adds instant fun to the
2000cc vehicles. The 34 ADF should always be mounted on the 1756 ADFA manifold.
If it fits your budget, consider the following combinations:
Table 11: Engine Component Combinations
Block and Head Intake Manifold Exhaust System Recommended Carburetor
2000cc
2000 FI Cylinder Head
Stock Pistons
1756cc 2000cc FI 4-2-1 Weber 34 ADF
or
Weber 28/36 DFEV
2000cc
1756 Cylinder Head
Stock Pistons
1756cc 1756cc 4-2-1
or
2000cc FI 4-2-1
Weber 34 ADF
or
Weber 28/36 DFEV
or
Weber 36 ADL