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Jet Performance Products - New AgainRestoring A Q-Jet With JET Performance Products From the February, 2009 issue of Chevy High Performance By Bob Mehlhoff Photography by Bob Mehlhoff
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Carburetors are still king under the hood in many of today's high-performance cars. Whether it's for traditional looks, the ease of tuning, or the great performance, these conventional fuel mixers live on. Like all parts, though, years of service and mileage can diminish performance, power, and miles. Inside your carburetor the gaskets may seep fuel from warped components, the throttle bores may wear, or the factory plating can fade and turn downright ugly. These kinds of carb problems generally cannot be repaired by a standard rebuild and require a specialized shop. For more serious performance levels, you may want proven modification to your Holley or Quadrajet. But whether you're looking for a total carburetor restoration or a modified carb to slash your e.t., there's good news. JET Performance Products has an in-house operation to perfectly fill your needs. To see how well this works we followed along as Johnnie at JET walked through the process of refurbishing a '67 Malibu's Quadrajet carburetor. Our carburetor is the original core that came fitted to the 275-horse 327ci small-block, so a factory restoration was preferred. If you elect to buy a carburetor outright from JET Performance, you'll be happy to know they usually have many on hand. Either way, you can have a carb catered for a mild to wild combination just a phone call away. Here's a quick rundown of the basic stages offered on the Quadrajet. If you're utilizing a Holley carburetor, there are more choices. To learn more, log onto www.jetchip.com and check out the Performance Carburetors section. Jet's Three Levels Of Performance
The Stage 1 Quadrajet begins with a complete disassembly, cleaning, and inspection. With the carburetor apart, all the casting plugs are sealed with a special epoxy to prevent fuel leak-down into the intake manifold. Next, all the carb circuits are checked for proper sizing, and the calibration is verified for correct jets and primary and secondary metering rods. Then the carburetor is reassembled with the highest-quality components including a new float, a choke pull-off, and bronze bushed throttle shafts. This stage is designed to restore your Q-jet to a factory-stock performance level.  The original Q-jet on this...  The original Q-jet on this '67 327 Malibu provided decades of great service and had been rebuilt a couple of times. Recently, the fuel-filter fitting began to leak, the main body's soft plugs leaked fuel from previous epoxy repairs, and the carburetor had extensive wear. Yes, the Q-Jet needed a thorough going-through. Since this project is largely a restoration, it received the Stage 1 build.  Johnnie at JET Performance...  Johnnie at JET Performance Products in Huntington Beach, CA, began the restoration by disassembling and inspecting the carburetor. As mentioned, JET offers the option to restore or modify Quadrajet and Holley carburetors for added performance. If you don't have a core, JET also sells Quadrajets and other carburetors outright. For the Q-Jet, most of the carburetors are based on cores from the mid-'70s up. For the Quadrajet carburetor series, JET offers three stages, depending on the vehicle's intended use and your budget. The Stage 2 incorporates all of the Stage 1 features plus a recalibrated idle, off-idle, main, accelerator pump, and high-speed circuits to match any engine modifications, such as intake manifold, headers, ignition, or mild cam change. Features include improved idle qualities, instant throttle response, and maximum torque and horsepower for street/strip and tow vehicles with modified engines. The Stage 3 Quadrajet is intended for serious street/strip and race applications such as circle track and NHRA stock and super-stock classes. This level uses an oversized 0.149-inch needle and seat assembly, and is the start to this fully modified race system. Main well size is increased and balanced to ensure proper top-end, high-rpm fuel flow. Extensive circuit modifications are done to keep the fuel curve correct throughout the rpm range and to obtain clean idle quality and instant throttle response for consistent race-winning performance.  The primary throttle bores...  The primary throttle bores on our Q-jet were worn and the source of a sticky throttle situation and engine vacuum leak. This is common on older carburetors.  Every removable part was disassembled...  Every removable part was disassembled and carefully inventoried before being sent out to be replated in the factory color.  The Q-jet's fuel-filter fitting...  The Q-jet's fuel-filter fitting threads were worn. Consequently, the fitting leaked fuel onto the intake manifold. To repair this, it'll have to be tapped and rethreaded with a special Helicoil. The previous JB Weld repair (below the fitting) will be ground off and resealed.  The carburetor's base plate...  The carburetor's base plate is trued flat on this spinning disc.  Before the throttle shafts...  Before the throttle shafts were reassembled, new bushings were installed and fitted.  Underneath the carburetor's...  Underneath the carburetor's base plate, these two plugs had been repaired. Since then, the metal (near the repair) had begun to break off and cause small leaks. This area will also be ground down and resealed. Next, all the parts will be chemically cleaned and sent out together for replating. Plan ahead, because replating an existing core typically takes a few weeks.  With all the parts cleaned...  With all the parts cleaned and plated, the carburetor is ready to be reassembled. All circuits were checked for proper sizing and the calibration was checked for proper jets, including both primary and secondary metering rods.  Next, Johnnie carefully checked...  Next, Johnnie carefully checked the movement of the throttle shaft to ensure free action without any binding.  With the old JB Weld epoxy...  With the old JB Weld epoxy cleaned away, a new special epoxy was applied over all of the carburetor body plugs to prevent leaking.  All new hardware was used...  All new hardware was used to reassemble the carburetor. During this process, all the movements were continuously checked and rechecked to make sure there isn't any binding.  Inside the main body, everything...  Inside the main body, everything is clean and fresh. On the Stage 1 carb, all the circuits will be checked for sizing and the calibration verified for correct jets and primary and secondary metering rods. For Stage 2, JET will fully recalibrate idle, off-idle, main, accelerator pump, and high-speed circuits to match any engine modifications, such as intake manifold, headers, ignition, or a mild cam change. Stage 3 provides extensive circuit modifications and more, depending on your requirements.  A new fitting with a filter...  A new fitting with a filter was reinstalled into the repaired threads.  When tightening the filter...  When tightening the filter fitting, be certain not to apply too much torque.  Finally, the carburetor was...  Finally, the carburetor was reassembled with all new components,...  ...including a new float and...  ...including a new float and choke pull-off.  The finished carburetor not...  The finished carburetor not only looks new, but after a basic blueprinting is in better shape than ever. JET Performance Products has been in the carb restoring business for years and can take almost any carburetor core, be it a Q-Jet or Holley, and make it look new again, as well as improve performance....  ...All you have to do is select...  ...All you have to do is select the type of performance you want.
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