Left: The accelerator pump discharge passages are enlarged for better fuel volume during acceleration. Middle: JET modifies the idle down-tubes for better idle characteristics and smoother transition into the main fuel-circuit. Right: A common malady in the Quadrajet is a stumble as the secondary air door opens. To alleviate that, JET modifies the secondary pull over circuit.
Well into the late ‘80s, a countless number of GM vehicles left the factory with the Q-jet. Those that loathed it, yanked it from the engine and replaced it with something else. Their common – and usually unceremonious – removal, means that they are still plentiful at almost any swap meet. Those that understand and appreciate the carburetor, also feel that it is a very desirable and tunable, four-barrel. Sure, it has more moving parts than any other carburetor, but that just lends validity to its adjustability.
If we receive a carburetor from a customer, it doesn’t matter what stage rebuild they need, they get their carburetor back. – Russell Wood
We mentioned that JET Performance is still steeped in carburetor performance, and they’ve been restoring, rebuilding, and modifying carburetors for more than four decades. What that means to you is: they have the parts and the experience to resurrect even a recycle-ready Q-jet back to life, making it look and run, better than new. But, JET doesn’t simply rebuild this marvel of fuel distribution.JET can also upgrade the rebuild process to include a multitude of features for various performance enhancements being utilized on a given engine. Depending on your needs, you can choose from a Stage 1, Stage 2, or Stage 3, rebuild. We asked Russell Wood of JET Performance to elaborate.
“We have various ‘stages’ of rebuilds. Stages 1, 2, and 3 vary in the applications they are intended to be used. Generally speaking, a Stage 1 rebuild is for stock or very mild performance applications. Stage 2 is intended for a vehicle with an aftermarket intake manifold, headers, ignition, and/or a performance-camshaft upgrade. Stage 3 is designed for serious street and strip, and race applications. We even have circle track applications. All carburetors that are sent to us, are calibrated for the specific application and use,” Russell said.
When a carburetor is sent in for a full-blown restoration, all of the parts are re-colored and re-plated to look OE correct. Most carbs are sent in for what is called a standard rebuild, where JET cleans the parts and makes sure they operate properly. For most applications, a standard rebuild is fine, and ensures it works like new.
Each JET-prepped carburetor has fuel jets installed to suit an individual application. You tell them how your engine is built and how it will be used, and they’ll build you a calibrated carburetor.
When a carburetor that needs rebuilt is for a “numbers-matching” restoration and the owner is concerned about keeping all parts original, according to Russell, that’s not a problem. “If we receive a carburetor from a customer, it doesn’t matter what stage rebuild they need, they get their carburetor back. That is very important to someone that is restoring a vehicle and wants to keep a numbers-matching carburetor on their restoration project,” he said.
The JET-prepped Quadrajet includes an APT (Adjustable Part Throttle) setting that can be manipulated after the carburetor is on the car. Here, the JET technician sets the base adjustment before final assembly.