Correct Wording for Level 1 and Level 2 Induction Systems
#29406 from Ron Bartell · Rule change · TB 20-12 (2020-12 Fastrack)
In Production, GCR section 9.1.5.E.1.b.1, make changes as follows:
"All inducted air must pass through the venturi(s) of the car’s carburetor(s). Any carburetor(s) with restricted venturi(s) must
retain such venturi(s) in the original location within the carburetor. The throttle plate, shaft location, and bore diameter (as
measured at the throttle plate) shall remain as specified. Carburetor jets, jet needles, metering rods and needle valves areunrestricted. Choke mechanisms, plates, rods, and actuating cables, wires, or hoses can be removed. The number and type of
carburetors must not be changed from stock, unless otherwise specified by the vehicles spec line. In all other regards, standard
and approved optional carburetor(s) are unrestricted.
All single carbureted cars may fit a permitted optional carburetor. Where the use of one (1) 40 DCN, DCNF, IDF carburetor is
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specified, a permitted optional carburetor may be substituted. Permitted optional carburetors are:"
In GCR section 9.1.5.E.1.b.4, make changes as follows:
"Fuel injection: All inducted air must pass through the throttle body and be subject to control by the throttle butterfly. The stock
throttle body casting/housing must be retained. The inside dimensions of the throttle body casting/housing (as measured at the
throttle butterfly) and all dimensions of the throttle butterfly must remain stock, but . T the throttle body can otherwise be
ported and polished. The dimensions of the throttle butterfly must remain stock. The throttle butterfly shaft shall not be
relocated. The outside diameter of the portion of the throttle butterfly shaft located in the throttle body bore must be no
smaller than stock. The contour of the interface between the throttle butterfly shaft and the butterfly must remain stock. The
throttle butterfly and any throttle butterfly to shaft screws/bolts can be attached to the throttle butterfly shaft by any means
including welding or brazing. Holes or slots can be created in the throttle butterfly for purposes of idle adjustment only. The
number of injectors must remain stock. The mounting position and the injection point must be stock. Electronic fuel injection
may be substituted for the stock type of fuel injection. In all other respects the fuel injection system is unrestricted."
In GCR section 9.1.5.E.2.b.1, make changes as follows:
"All inducted air must pass through the venturi(s) of the car’s carburetor(s). Carburetor jets, jet needles, metering rods and
needle valves are unrestricted. Choke mechanisms, plates, rods, and actuating cables, wires, or hoses can be removed. The
number and type of carburetors must not be changed from stock, unless otherwise specified by the vehicles spec line. In all
other regards, standard and approved optional carburetor(s) must not be modified.
All single carbureted cars may fit a permitted optional carburetor. Where the use of one (1) 40 DCN, DCNF, IDF carburetor is
specified, a permitted optional carburetor may be substituted. Permitted optional carburetors are:"