Engine Maintenance and Modification Bradley Artigue

FIAT 124 Spider
Engine Maintenance + Modification
4.8.3 Weber IDF
European 1608 Sport Spiders produced from 1971 until 1973 were fitted with dual
Weber 40 IDF carburetors. Although never an option for U.S. cars many of the manifolds
and carburetor pairs were installed on Spiders of virtually every engine displacement
from 1608 to 2000. Although no FIAT manifold directly fit the 1438 series, an Abarth
manifold was produced that would allow for IDFs on that engine.
The FIAT Abarth Spider CSA (1972), a rare factory produced street version of an Abarth
race car, was also fitted with dual IDFs. The actual racing version had dual 44 IDFs
carburetors or mechanical fuel injection.
Figure 14: IDF Carburetor Side View
Through needle valve (6) fuel passes into bowl (2) where float (3), hinged on pivot pin (1),
controls needle (5) stroke to keep the fuel level constant. Needle (5) is connected to the
lug of float (3) via return latch (4).
Figure 15: IDF Normal Operation
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