It’s been roughly 54 years since General Motors released their Quadrajet four-barrel carburetor, and along the way, it’s given thousands of us something to love and hate. Commonly referred to as the “Q-Jet” or “Rochester Quadrajet” because it was created by the Rochester Products Division of General Motors, it was first used in the ’65 Chevy 396 and last used in the Cadillac Brougham. Though it served its purpose, the Q-Jet has a huge list of disadvantages that seems to outweigh its advantages, but now we can all put that behind us thanks to Holley’s Sniper EFI Quadrajet—a self-tuning EFI system that is done using a handheld EFI controller.

For this particular install, we used PN 550-867 and it’s the first bolt-on spread-bore electronic fuel-injected throttle-body system that does not require any additional adapters, sealing plates, or intake manifold swaps. The Sniper EFI Rochester Quadrajet™ (Q-Jet) system retains the same great features as the 4150 Sniper EFI version such as: four 100-lb/hr injectors, built-in timing control, a 3.5-inch full-color touchscreen and let me tell you how handy that is. The installation was something most could tackle and programming was insanely simple. In years past, the “programming” aspect of many of these upgrades scared many away, but this new system only requires you answer just a few questions before it takes over and handles the rest.

So, how does it do with power gains? Well, the throttle body will support up to 500 hp naturally aspirated, and the Sniper EFI Rochester Quadrajet™ (Q-Jet) system will fit most stock air cleaners while offering multiple fuel inlet configurations that allow for a stock appearing installation!

For our particular install, we opted for the “shiny” finish, but it’s also available in Classic Gold and Black Ceramic. In all, the installation is simple (something we’ll follow up on shortly), but the key point here is that it’s easier to tune and designed to deliver the signature Rochester Roar at wide-open throttle minus all the drawbacks from the original design. In addition, you do not need a computer since all programming is done using their touchscreen unit which can be calibrated by answering just a few questions.

Other key features of this incredible unit include:

  • Throttle-body-mounted ECU—no extra boxes to mount
  • Supports up to 500 hp with Four 100-lb/hr Injectors!
  • Only 4 Wiring Connections Required! (Battery +, Battery – , Switched Ignition & RPM)
  • Integrated ignition timing control
  • Transmission provisions on throttle lever for TH350/TH400 and 200R4/700R4
  • Fits most stock Rochester Quadrajet™ (Q-Jet) air cleaners
  • Brake Booster adapter included, if required
  • Universal Throttle and transmission kickdown bracket included
  • High-Resolution Full-Color Touchscreen for Initial Setup, Tuning, and Gauge Displays.
  • The included Genuine Bosch LSU 4.9 Wideband Oxygen Sensor provides real-time Fuel Map Learn!
  • OEM Style Throttle Position Sensor (TPS)/ and Idle Air Control (IAC) for years of dependable service.
  • Included clamp-on oxygen sensor kit ensures a leak-free oxygen sensor installation, with Stainless Steel T-Bolt clamps and a Stainless Steel (Weldable) oxygen sensor flange
  • Requires external fuel pressure regulator, such as: 12-886 or 12-879
  • Certified to ISO 8846, SAE J1171 and United States Coast Guard Requirements for Ignition Protection & Fire Resistance.