Because there were slight differences between the size and shape between the old carburetor and the new Holley throttle-body, Green had to make minor adjustments to the Corvette’s throttle linkage for it to work properly. Once this was done, the various sensors in the kit were installed and connected to the computer’s wiring harness. These included the Manifold Absolute Pressure Sensor, Idle Air Temperature Sensor, and Throttle Position Sensor. You’ll also have to make a hole in your exhaust system for the Oxygen Sensor. The kit comes with a small bung that must be welded onto your exhaust, allowing you to screw the O2 sensor into position. The instructions will tell you the best location along the exhaust to make this modification, and Green followed its advice and attached it as close to the header collector as possible.
The system also comes with a Water Temperature Sensor that can be installed into the threaded hole typically used for the water temperature gauge-sending unit. You can use the tapped hole in the manifold for the new sensor, but if you need it for your gauge you can use a T-fitting to operate both. Once all the sensors are installed, the main control unit needs to be routed and plugged into the harness.
The ECU that operates the EFI system should be mounted in a location away from heat. This can vary depending on your vehicle and any accessories you have on it. Green built a small panel that allowed the ECU to tuck away neatly inside the inner fenderwell of the Corvette, between the passenger wheelwell and firewall. Since the Corvette will have aluminum panels covering the inner fenders, this made a safe location to protect the ECU from heat and moisture. No matter where you decide to mount your ECU, Green recommends trial fitting everything first.
The wiring harness also has separate power leads to operate the hand-held tuner and the fuel pump relay. You can take a 12V key-on ignition source from your Chevy’s fuse box and attach another lead directly to the battery. A system like this one also has provisions to use with various types of ignition sources. The Holley unit uses an ignition trigger for the injectors. So it’s wise to read the instructions carefully to see all of the scenarios available and wire the trigger lead according to which type of ignition system the vehicle is using. In this application, the Corvette had an MSD Digital Ignition box, which provides an ignition trigger on the side of the unit. This made it easy to wire the fuel injection trigger lead directly into the box.
Once everything was wired and plumbed, Green turned the ignition key and the LCD display on the hand-held turner turned on. It features a simple menu, allowing you to select approximate engine size, horsepower, transmission, and other basic variables of your application. If you’ve ever installed a power programmer onto your late-model vehicle, you can easily operate the Holley unit. Once the selections were made for this particular Corvette, Green turned the ignition to the “on” position and made sure there weren’t any fuel leaks. Then he cranked the engine over and it started without any hesitation. The Holley ECU automatically fine-tunes the fuel and ignition timing to the engine and also takes into account your driving habits to optimize fuel delivery.
The total time it took to install in this application was about six hours. But no laptop or additional tuning on the dyno was needed. It will be a while before the Corvette gets back on the road and to the track, but judging from the smooth idle from this 500hp street engine, we bet it will perform admirably on both the street and strip. Holley also makes a similar self-tuning system in a multiport fuel-injection design that is available for a variety of engine sizes and applications. But the Avenger EFI system is probably the easiest to install, and can really make a difference in improving your Chevy’s power and fuel economy in a matter of hours.

The Corvette uses a fuel cell...

The Corvette uses a fuel cell that was located in the trunk. Because most fuel cells have AN fittings, both the fuel out and return lines were easily plumbed into it.

The computer is small and...

The computer is small and can be mounted just about anywhere. In this application, it was mounted onto a piece of sheetmetal that will sit in the Corvette’s inner fender.

No matter where you decide...

No matter where you decide to mount the system’s ECU make sure you have plenty of room to plug in the wiring harness to it.

The harness must also be attached...

The harness must also be attached to the idle air temperature sensor on the throttle body.

Another connection to the...

Another connection to the throttle position sensor on the throttle body is also plugged in.

A small NOS solenoid bracket...

A small NOS solenoid bracket was modified to hold the MAP sensor in position and was then bolted to one of the throttle-body studs on the intake manifold.

The wiring harness also has...

The wiring harness also has two 12V sources with fuses that attach to a key-on source and directly to the battery.

An MSD Digital ignition system...

An MSD Digital ignition system already installed provided an easy ignition trigger point to plug in the lead for the harness. Note: The system will work with a variety of ignition sources.

A relay for the fuel pump...

A relay for the fuel pump is also wired and attached in a safe location in the trunk. This will turn on the fuel pump when you turn on the key and prime the system with fuel.

Green had to make minor adjustments...

Green had to make minor adjustments to the throttle cable and linkage to operate the throttle body; just make sure it opens the throttle blades fully.

The Holley handheld tuner...

The Holley handheld tuner is easy to use by making the appropriate selection from the menu screen and the system will learn the rest. There’s no need to program or make changes from a laptop computer.

Once installed, this 427 small-block...

Once installed, this 427 small-block fired right up. After a bit of seat time, Holley’s EFI system will self-tune and provide even greater fuel economy and performance from this engine.