Replacing your carburetor with fuel injection has never been easier. Throttle body injection (TBI) systems will often work great with your current engine setup and support future upgrades (like a power adder or timing control) if you choose the appropriate system up front.

EFI kits are sized by the maximum horsepower they can support with gasoline, and are designed to work across a wide horsepower range. Some systems are compatible with E85 but at a reduced maximum horsepower rating, because E85 requires a richer air/fuel mixture.

OnAllCylinders contributor Jeff Smith showed us this Holley Sniper throttle body EFI system on a street-driven 1966 El Camino packing a 468ci Chevy Big Block. (Image/Jeff Smith)

Most universal TBI systems will also bolt up to your existing 4150-flange intake manifold. There are also 2-barrel, 6-pack, and dual-quad systems available that all significantly improve drivability.

The majority of modern EFI kits are self-tuning speed density systems that use minimal sensors for a simple installation: a throttle position sensor, MAP sensor, tach input, coolant temperature sensor, and a wideband O2 sensor for precise air/fuel feedback.

Recommended Reading: EFI 101: Mass Air vs. Speed Density — What They Are & Which is Best for Your Ride

The setup is basic; simply select your number of cylinders, displacement, ignition type, camshaft profile, and fuel (if compatible with fuels other than gasoline), and the self-learning system adapts as you drive. User tuning is usually confined to target air/fuel ratio, idle rpm, cold start enrichment, and deceleration fuel cut-off.

They’re not all based on a single carb setup either: Check out this this Chevy 383 Stroker using a Holley EFI system to feed eight individual velocity stacks. You can see more of this wicked-cool C3 Corvette here. (Image/OnAllCylinders)

If a system is compatible with timing control or power adders, those adjustments must be tuned by the user—the manufacturer can offer additional support for your individual setup.

Some kits include a fuel pump, however, any fuel pump that provides the correct pressure and volume can be used.

Typical EFI fuel system upgrades include:

Confused about EFI fuel demands? Read this: Return or Returnless: Which Fuel System is Right for You?

Depending on system psi, you may be able to use existing fuel lines, but replacing them is highly recommended.

You can see a wide range of throttle body fuel injection systems at

And if you’d like to learn more about how these systems work, click here for Summit Racing’s tech section on EFI.

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Author: Dave Matthews

Dave Matthews was a mechanic for the U.S. Army, a Ford dealership, and served for many years as a fleet mechanic for construction companies. Now a technical content producer at Summit Racing, Dave has spent decades working on everything from military vehicles to high performance race machines.