Mark Houlahan
Tech Editor, Mustang Monthly
October 22, 2013

It seems electronic fuel injection conversions are the hot topic on the Interwebs right now. While there have been EFI conversions happening since the mid-'80s (mostly with OE components and studying factory wiring diagrams until your eyes cross), it is the current crop of square-bore “bolt-on and go” systems designed for engines wearing carbureted intake manifolds that are getting all the attention right now. Rightfully so too, as these systems allow any owner with basic screwdriver knowledge and ability to follow an instruction manual to upgrade their vintage Mustang from carbureted to fuel injected in a weekend. Gone will be the hard cold starting, the hesitation on acceleration, the fuel leaks on the intake manifold, and all the other associated issues that come with dealing with carburetors and running them with today's fuels.

One of the newest members of the club is MSD. Known for their ignition systems for well over 30 years, they've come to the table with an interesting bolt-on EFI solution called Atomic EFI (PN 2900, $2,428.60). The Atomic system is a self-learning system and uses a carburetor-like square-flange (typical Holley 4150/4160) base to allow simple bolt-on mounting to factory or aftermarket intake manifolds. An adapter plate can be used for stock iron 4V manifolds with a little work (available from companies like TransDapt or Summit Racing).

The similarities to a carburetor end at the mounting configuration, however. The rest of the Atomic EFI unit is all modern tech. You'll find four 80 lb/hr injectors, two per side, that feed the annular fuel rings in the unit. These rings ensure the best fuel atomization. The unit also features an internal fuel rail so no external fuel fittings/rails are required. Lastly, the ECU is mounted directly to the throttle body unit. This reduces wiring runs and keeps all of the system's sensors in the throttle body itself except for the coolant temperature sensor and the oxygen sensor.

Of course, the system isn't just the throttle body. The Atomic EFI includes a feature-packed power module that controls the fuel pump and optional fan control, and connects the wide-band oxygen sensor (the main piece of hardware that allows self-learning of your vehicle's system needs) and handheld unit to the system as well. Also included in the system are a fuel pump, fuel filter, and fuel hose kit for return-less style fuel system plumbing. The pump can be used as a return-style with the addition of a regulator and additional fuel line (which is how we're going to install ours).

The wiring is simple with only eight connections, allowing anyone to get the system wired easily, even if you're far from a wiring pro. Lastly, the included handheld offers a way to adjust the system parameters and read many of the system's output information values such as coolant temperature, air fuel ratio, rpm, and more.

We're following along on an installation being performed on a customer car at Classic Creations of Central Florida so we can show you just how simple this is.

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23. All buttoned up and with the customer’s oval air cleaner reinstalled, the Atomic EFI becomes nearly invisible to the untrained eye. The driver’s side looks just like an aftermarket carburetor, including the linkage. It would take a fairly observant person to notice the extra wiring and control module buried behind the engine.