EFI Conversion, Holley, Sniper EFI, 1974-78 GM, 2GC Large Bore

1974–78 GM Rochester 2GC Large-Bore Sniper EFI Conversion Kit by Holley®

Large-bore two-barrel EFI replaces Rochester 2GC carburetion with self-learning fueling.

This Holley® Sniper EFI conversion is designed for 1974–78 Chevrolet, GMC, Oldsmobile and Pontiac engines originally fitted with the Rochester 2GC large-bore two-barrel carburetor. The throttle-body unit mounts to the matching two-barrel intake pattern and replaces carburetor fuel metering with electronic injectors controlled by a self-learning ECU. An included wideband-oxygen feedback system monitors combustion mixture and refines the fuel map after initial setup using the color handheld controller. The unit mounts its ECU directly to the throttle body, uses two 100-lb/hr injectors and is rated for up to 350 naturally aspirated horsepower. Setup uses a 3.5-inch color touchscreen and just four basic wiring connections; the guided calibration wizard begins the tuning process without a laptop. Integrated ignition-timing control is available with compatible ignition components. An internal regulator targets approximately 58.5 PSI and the system includes a Bosch LSU 4.9 wideband oxygen sensor and clamp-on exhaust mounting hardware. The standard package requires a suitable EFI fuel system; the master selection adds an external high-pressure fuel pump, two filters, 20 feet of fuel hose and the required fittings. These packages are not intended for the small-bore 2GC flange.

• 1974–78 GM original large-bore Rochester 2GC • Two-barrel electronic fuel injection • Self-learning fuel map from oxygen-sensor feedback • Handheld calibration and monitoring • Up to 350 HP with two 100-lb/hr injectors • Base and master fuel-system selections • Not for Rochester small-bore 2GC