1957 - 1958 Corvette: Service Bulletin: Fuel Economy Drop - Rochester Fuel Injection Service Update
Subject: FUEL ECONOMY DROP - #7014800 FUEL INJECTION UNIT
Model and Year: 1957 - 1958 Corvette
Source: Chevrolet Central Office Technical Service bulletin
Bulletin Number: DR #329
Date: November 21, 1957
TO: ALL CHEVROLET DEALERS
Progressive and gradual lowering of Fuel Economy on units equipped with #7014800 Fuel Injection may be due to partial restriction of the .030" venturi signal bleed hole in the air meter.
A dirt build up at this point gradually reduces the amount of signal bleed off, resulting in a progressively stronger venturi signal and increased enrichment.
The following procedure is recommended for cleaning the bleed hole. (Reference 1958 Passenger Car Shop Manual, Page 10-74, Figure 136).
- Remove air cleaner assembly.
- Remove four (4) screws holding air meter diffuser cone and remove diffuser cone only. Do not remove venturi ring.
- Locate bleed hole on the interior surface of the air horn which is positioned on the horizontal centerline, on the rear side of the interior wall, approximately " in from the air cleaner attaching surface.
- Insert a .030" wire at approximately 45o to the surface to clean out the hole.
- Install diffuser cone and air cleaner assembly.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
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