Editing Quadrajet (section)
Jump to:
navigation
,
search
==Drawbacks== Significant negative features of the Quadrajet were: * Leaking fuel bowl. As in nearly all carburetors, the Quadrajet float bowl has pressed-in plugs used to seal holes left after drilling fuel passages during the manufacturing of the carburetor. These plugs in the Q-jet sometimes leaked fuel causing: ** cold engine being hard to start ** erratic idling ** poor fuel mileage ** excessive emissions :Fortunately, leaking well plugs is primarily a problem only on the first few years of production when pressed in cup plugs were used instead of the later (and better) spun-in aluminum plugs that were swaged in place. Many Quadrajets have their fuel bowl plugs sealed with epoxy when rebuilt to prevent leaks. This may be good for a short time but epoxy will not stand up to the extreme conditions (heat and fuel contact) encountered for long. * The small float bowl can result in fuel starvation in extreme high-performance situations, but can usually be traced to a fuel delivery problem to the carburetor, such as a worn fuel pump, pump push rod, or camshaft eccentric. In normal driving and even off road performance use it provides excellent control of the fuel level. * The fuel inlet/fuel filter housing threads tend to be very fragile, possibly exacerbated by exposure to ethanol since the mid-2000s. It is common for the fuel inlet threads in the main casting to strip. There are several "fixes" available in the aftermarket: New oversize self-tapping fuel filter housings; new fuel filter housings that seal with O-rings; and Heli-Coil rethreading kits. * Almost all Quadrajets today have some amount of warpage of the castings. The root cause of this warpage is often over-tightening the front two carburetor mounting bolts, often in combination with a base gasket that doesn't have hard nylon inserts for the bolt holes. Without the inserts the base gasket can compress, warping the castings. A warped casting and/or airhorn can sometimes be unwarped using a special tool or sent to a professional service. * The steel primary throttle shaft will tend to wear the aluminum casting material. This results in an air leak and in extreme cases could cause the primary throttle blades to not close properly. This can result in poor idle quality and unfiltered air to be pulled into the engine. The aftermarket has responded; several vendors are supplying bushing repair kits for the Q-jet throttle body. * The idle tubes (which are located in the main casting) are usually sized at .031" or smaller (especially if it was used with a Chevrolet 305 (including the E4M and dual discharge pump models). These idle tubes are retained with a press fit collar. The bottom of the idle tubes may become plugged up with debris so care should be taken to clean this area. Idle tubes can be fine-tuned and opened up with numbered drill bits.
|
Editing help
(opens in new window)
Personal tools
Log in / create account
Namespaces
Page
Discussion
Variants
Views
Read
Edit
View history
Actions
Search
Navigation
Main Page
Recent changes
Random page
Help
All articles
Start a new article
Hotrodders forum
Categories
Best articles
Body and exterior
Brakes
Cooling
Electrical
Engine
Fasteners
Frame
Garage and shop
General hotrodding
Identification and decoding
Interior
Rearend
Safety
Steering
Suspension
Tires
Tools
Transmission
Troubleshooting
Wheels
Toolbox
What links here
Related changes
Special pages
Terms of Use
Copyright
Privacy Policy
Your Privacy Choices
Manage Consent