Installation of Dual Carburetors The original 1969 Alfa, as imported into the US, employed a mechanical fuel-injection system. Though considered advanced at the time, the fuel-injection system proved difficult and troublesome to tune. In order to upgrade the restoration car to a vehicle that can be custom-tuned to peak performance, twin two-barrel carburetors are installed on the Alfa. Where a traditional performance-carburetor (figure A) -- such as one that might be used on a domestic V8 engine -- the fuel and air charge are delivered vertically. By contrast, on the two-barrel carburetors, the fuel and air are delivered horizontally (figure B). Twin side-draft carburetors such as these were used extensively in racing vehicles, and may be precision-tuned to achieve customized performance in the vehicle. Installing carburetors such as these does involve some special requirements in coordinating elements such as fuel pumps and fuel lines. Those parts, installed earlier on this vehicle, were checked to ensure compatibility with these carburetors before the fuel-system installation began. Following is a summary of the major steps in the engine reinstallation as shown in the episode.
- The first step in the carburetor installation is to place the two throttle shafts side-by-side and lock them together (figure C). This orientation is critical since it allows the throttle shafts to open in unison during acceleration.
- The two carburetors are positioned onto the mounting studs (figure D) and fastened with nuts.
- The nuts are tightened carefully using an open-end or box wrench (figure E ). Needle-nosed pliers are also helpful in this process as they help in installing the nuts on some of the hard-to-reach studs.
- With the carburetors mounted, the throttle linkage is connected and checked for proper spring-back and operation (figure F).
- Next, air-cleaners and covers are installed. These are foam-style cleaners are covered by a chrome cage (figure G).
- The covers are held in position by wire retainer-clips (figure H). The clips make it easy to remove the air cleaners later for cleaning or replacement.
- With the covers installed, the fuel line is installed between the first and second carburetor (figure I).
- Next, the final fuel line is attached to the rear carburetor (figure J). This line drops back behind the engine, and connects at its other end to the original fuel line coming up from the fuel tank.
- With the lines installed, they are fastened securely with hose clamps (figure K).
- The installed carburetors (figure L) are then adjusted to synchronize the throttle shafts. It's critical that both two-barrel carburetors, and the individual throttle plates, open simultaneously to optimize fuel-flow through the carburetors. This ensures that all cylinders receive the same fuel-air mix to help the engine run properly. With this new carburetor system, the Alfa's engine can run on unleaded premium gasoline, and can be custom-tuned to optimize performance using that type of fuel.
In the segment that follows, a new exhaust system is installed on the Alfa.
RESOURCES :
Alfa Romeo Owner's Bible: A Hands-On Guide to Getting the Most from Your Alfa
Model: 0837607078
Author: Pat Braden
Order this book from Amazon.com
Bentley Publishers
Alfa Romeo Spider: The Complete Story
Model: 1861261225
Author: John Tipler
Order this book from Amazon.com
Crowood Press
Original Alfa Romeo Spider (Bay View Original Series)
Model: 0760311625
Author: Chris Rees, James Mann
Order this book from Amazon.com
Motorbooks International (MBI Publishing)
Essential Alfa Romeo Guilia & Giulietta Coupes & Spiders: The Cars and Their Story 1954-95
Model: 1870979591
Author: David Hodges
Order this book from Amazon.com
Motorbooks International (MBI Publishing)
Alfa Romeo: The Spirit of Milan
Model: 0750919582
Author: David G. Styles
Order this book from Amazon.com
Sutton Publishing
Classic Car Restorer's Handbook: Restoration Tips and Techniques for Owners ...
Model: 1557881944
Author: Jim Richardson
Order this book from Amazon.com
H.P. Books
Classic Car Restoration Guide: The Complete Illustrated Step-By-Step Manual
Model: 1850108900
Author: Lindsay Porter
Order this book from Amazon.com
Haynes Publishing
| 
)
)
)
)
)
)
)
)
)
)
)
)
)
)
