Converting an engine originally equipped with a carburetor to electronic fuel injection (EFI) is nothing new; though every year it seems as if interest in taking the EFI plunge gains momentum. OEM vehicles of the past two decades have firmly engrained the advantages of fuel injection to all but the most diehard enthusiasts. Far be it from us to suggest taking a show-bred Corvette and altering it in such a way. however, if serious road time is more important than originality in your Vette escapades, retrofitting to EFI is a modification worth considering. Late-model performance cars, such as the C5 and C6, provide all the evidence necessary to show the attributes of injection, including flawless drivability and remarkable reliability. Wouldn't it be nice to take some of that technology and apply it to an earlier carbureted Corvette?
For the vast majority of enthusiasts, the thought of running a custom aftermarket EFI system is filled with trepidation. Sure, it seems to work great on modern cars, but just what is involved in setting up an older engine to work with this modern technology? At first glance it might seem pretty complex, with items such as the wiring, sensors, the control box, and so on. In comparison to that old Quadrajet, it certainly involves more hardware and at a more sophisticated level, but breaking it down is nothing a seasoned wrench-turner couldn't handle. We sought just such a conversion to a small-block Chevrolet engine and found the changeover less daunting than anticipated, using components from FAST.
The basic hardware change...
The basic hardware change when making the move to EFI is the intake manifold, which isn't terribly surprising since we are talking induction systems here. One of the key components is the intake manifold, and there are a myriad of choices. There are purpose-built EFI manifolds available from the aftermarket, and some available with EFI bosses cast in, which need machining to accept the injectors. Manifolds originally intended for carbureted applications can also be readily adapted, as evidenced by our own Edelbrock Victor Jr. Note the injector bungs TIG welded to the runners on this intake. The universal bungs are available from FAST.
Back in the early days of EFI conversions, most efforts centered upon adapting the primitive OEM components of the time to vintage iron. Installing the hardware was simple enough, but the difficulty stemmed from gaining control of the tuning parameters. Such installations nearly always involved modifications to the factory specifications, and the control units that provided the logic to run the systems were notoriously inflexible. Times have changed, and these days companies like FAST do the work to produce components that have been designed to work together, in a wide range of potential applications. the technology is built into the system, so the end user does not need to be a fuel-system engineer. The software facilitates tuning the system to an unbelievable degree, making such installations flexible in controlling a wide range of likely combinations.
Whether you are looking to inject an older Corvette cruiser, or are looking to plant a modern, fuel-injected monster in your radically modified C3, the systems to make it happen have already been ironed-out to the nth degree.
Supplying the fuel to the...
Supplying the fuel to the injectors is the fuel rail. Some means of holding the rail at a fixed distance to the manifold is required to keep the rail/injector assembly in place on the intake manifold. This manifold was tapped to accept simple brackets at each end of the rail. There are many specialty shops that can perform all of the modifications required to convert an intake to EFI for a custom installation, including FAST fuel injection. Holley, Edelbrock, and others have off-the-shelf intakes designed to accept rails and injectors.
An EFI throttle body will...
An EFI throttle body will have a device called an idle air controller (IAC), which takes care of the idle functions of the engine. Basically, an electrically operated motor opens and closes a small air passage through the throttle body that provides the engine with the air requirements for idle. The IAC can continuously adjust the idle settings, attempting to make it perfect at all times under varying conditions. In contrast, a carburetor just has the throttle blades hung open a fixed amount by the idle speed screw.
EFI injectors are a slip-fit,...
EFI injectors are a slip-fit, and seal via o-rings. The key to injector selection is sizing, designated in lb/hr of flow. The key to sizing is to make sure the injectors flow enough fuel for the max power the engine will be capable of. FAST's tech line can provide injector flow rates based upon the maximum anticipated power output.