The Sniper EFI Quadrajet throttle body is a bolt-on EFI conversion for Rochester Quadrajet-equipped classics, designed to fit the factory spreadbore intake without an adapter, sealing plate, or intake swap. It carries over the same core features as the 4150-flange Sniper EFI system — four 100 lb/hr injectors, built-in ignition timing control, and a 3.5" LCD touchscreen — in a housing that fits most stock air cleaners and factory-appearance installations.
Key Features:
- Fits most stock Rochester Quadrajet air cleaners without modification
- Certified to ISO 8846, SAE J1171, and USCG ignition-protection and fire-resistance requirements for marine use
- 3.5" LCD handheld touchscreen for setup, tuning, and gauge display
- Integrated ignition timing control when paired with HyperSpark distributors and Holley Dual Sync
- Fuel pump outlet wire with a built-in relay to power the fuel pump directly
- Calibration wizard builds a base tune with no laptop required
- Includes universal throttle bracket, transmission kickdown bracket, and brake booster adapter
- Bosch LSU 4.9 wideband oxygen sensor for real-time fuel map learning
- Built-in MAP and IAT sensors adjust automatically to changing conditions
- Four 100 lb/hr injectors and a 715 CFM throttle body support up to 500 HP naturally aspirated
- Throttle-body-mounted ECU keeps the engine bay clean
- Three ground-trigger outputs for accessories such as cooling fans or A/C
- Simple four-wire installation: Battery+, Battery-, 12V switched ignition, RPM signal
Specifications:
- Flange Style: Spreadbore (Rochester Quadrajet)
- CFM: 715
- Throttle Bore: 1.375" primary / 2.00" secondary
- Max Horsepower: 500 naturally aspirated
- Injector Size: 100 lb/hr @ 58.5 PSI
- Fuel Pressure: 58.5 PSI
- MAP Sensor: 2-bar
- Finish: Classic Gold
- User Interface: 3.5" LCD touchscreen handheld
- Transmission: 700R4/200R4 kickdown compatible
- Coast Guard Approved: Yes, for marine installation
- Part Number: 550-869
For marine installations, a flame arrestor is legally required — Holley recommends part 720-1 or 720-11 with a 720-31 or 720-33 vent tube for proper function and compliance.
FAQ
Will the 550-869 fit my factory spreadbore intake?
Yes. It's designed to bolt directly onto a factory Quadrajet-style spreadbore intake without an adapter or sealing plate.
What horsepower does this throttle body support?
Up to 500 HP naturally aspirated, using four 100 lb/hr injectors.
Can this be installed on a boat?
Yes, it's Coast Guard approved and certified to ISO 8846, SAE J1171, and USCG ignition-protection standards, but a legally required flame arrestor must be added for marine use.
Do I need a laptop to tune this system?
No. The 3.5" LCD touchscreen handheld runs a calibration wizard that builds a base tune, then the system self-tunes.
Does this fit standard air cleaners?
Yes, it fits most stock Rochester Quadrajet air cleaners without modification.
