The heart of the matter is the Atomic EFI unit from MSD; it has the power to transform you
Don’t let the name fool you. While the Atomic Age was actually ushered in around 1945, this new electronic fuel injection from MSD packs explosive power, reliability, and fuel economy all wrapped up in one compact system, and it’s driven by the latest technology the 21st century has to offer.
One of the ongoing attractions to a great hot rod is simplicity. The fact that you can work on hot rods in a parking lot and generally get them running again without any special equipment is a comforting feeling while heading off on a long trek. Anyone driving a vintage vehicle has heard this from a spectator, “Ah, yes, these were great cars, back when a guy could work on the motor himself.” A more accurate statement might be, “Ah, yes, these were great cars, back when a guy had to work on the motor himself.”
While there was absolutely nothing wrong with the carburetor on the 350, Magoo felt it was
While I may not be leading the technological charge I at least ditched the old points distributor years ago on both the small-block Chevy in my ’40 and the trusty Y-block in the ’57. Electronics in distributors are reliable and widely accepted and yet many hot rodders seem reluctant to convert from carburetion to electronic fuel injection. A lot of this trepidation is based on tales of early electronic fuel injection systems, but there have been huge advancements in retro-fit EFI fuel injection over the past few years.
The ’63 Chevrolet receiving the Atomic EFI conversion belongs to one very traditional hot rodder. A man who made his name in street rodding by producing fabulous traditional roadsters well before the latest wave of vintage style came into vogue. The owner is none other than Dick “Magoo” Magugorac. While the ’63 still carries a traditional theme (and Magoo red paint), Magoo realized it was time for more modern driveability. When someone as steeped in the tradition as Magoo goes EFI it just might be time to consider putting the ole carb on the shelf. One look at the installation of the Atomic EFI from MSD has me rethinking the concept of using three carburetors to feed a motor, when one EFI would do a superior job. (Magoo tells us that the Chevy has jumped 4 mpg and with this comes ease of starting, enhanced driveability, and improved throttle response.)
Anthony Monacelli (left) and Magoo at Hot Rods by Dean disconnected the fuel line, linkage
It would appear that many street rodders are having similar feelings, so we tagged along, camera in hand to follow the team at Hot Rods by Dean as they did a typical MSD Atomic EFI installation. One indication that these guys are real pros came early on when we caught Anthony Monacelli actually reading the instructions before work began; what a concept. This no doubt contributed to the quick installation time.
There was a time when using an EFI motor in a street rod required planning from the ground up, retro-fits were difficult. From the huge wiring harness to the sensor locations, early EFI motors seemed complicated, but thanks to MSD all of that has changed. That huge wiring harness has been reduced to a simple eight-wire harness. By locating the throttle position switch (TPS), the manifold absolute pressure sensor (MAP), the intake air temperature sensor (IAT), and the fuel pressure sensor in the actual throttle body, the MSD Atomic EFI has reduced the sensor installation to a pair of very easy installations. One is the temperature sensor, which is a simple matter of draining the coolant and installing the sensor in the intake manifold, much like installing a gauge sending unit. The other sensor is the O2 sensor and the supplied bung must be welded into the exhaust system reasonably close to the motor. One other note, while you are welding in the exhaust bung for the O2 sensor, check out your exhaust system. Exhaust leaks upstream can raise havoc with O2 readings, so be sure your exhaust system is tightened up; of course even if you are running a carburetor exhaust leaks should be unacceptable.
The only other part required for the conversion was this Holley 700-R4 kickdown bracket. T
Another old stumbling block for EFI installations was the need for a return line to the fuel tank. This problem has also been eliminated with the Atomic EFI as they have electric fuel pumps that provide you with the option to use a return line or to use a pulse-type pump that does not require a fuel return line.
With the two sensors located you can disconnect the fuel line, throttle linkage, and kick-down linkage from your carburetor and then unbolt the carburetor from the intake manifold. Since the Atomic EFI fits any square bolt-pattern intake, installation is as simple as slipping the new gasket down over the studs and bolting the new Atomic EFI throttle body injection onto the existing intake manifold. Because the throttle body carries linkage just like a carburetor, our Lokar cables bolted right back in place. By using a Holley PN 20-121 (sold separately) you can provide the correct pressure to your overdrive (GM 700-R4 or 200-4R) transmissions.
Next, disconnect the battery to ensure there is no power to any circuits. From here it’s a matter of following the detailed wiring instructions. MSD Atomic Fuel Injection power module can also control timing and covers functions like automatic idle kickup when the A/C is running. The module will also control cooling fans and the electric fuel pump and it is all done by following the detailed wiring instructions. There’s little need for us to go wire by wire on this page as it is all laid out in the instructions, and we did supply a schematic of the wiring sourced from the MSD website. Dedicated plugs make the connections reliable and relatively fool proof.
While the carburetor was removed the phenolic heat insulator remained in place; all fuel systems can benefit from an insulating plate.
The Holley kickdown bracket (PN 20-121) for the 700-R4 was bolted in place on the bench prior to installing the EFI throttle body.
Under the finned endcap of the Atomic EFI you will find the CPU that does all the “thinking” for the EFI. This throttle body is an ingenious bit of packaging.
Hot Rods by Dean’s own Anthony Monacelli bolts the throttle body down to the Edlebrock intake manifold. This unit will fit any square base four-barrel intake.
With the unit bolted in place the kickdown rod and the Lokar throttle cable connect just like they did before. Note the double return spring on the linkage, a good idea on all linkage.
The only adjustment to the Atomic EFI is setting the throttle blades in the bottom of the unit; a quick eyeball showed they would need to be “tweaked” into spec.
An Allen wrench in the forward adjuster dials in the front set of blades, the actual procedure is covered in the detailed instructions.
Moving to the rear the same Allen wrench brings the back blades into spec, it is a simple adjustment.
It doesn’t get any easier than this, on the left is the power module, on the right is the handheld unit used to configure the system prior to the first startup.
The power unit can be mounted anywhere in the car, cable extensions are available from MSD. We opted to mount the unit on the firewall.
Remember those huge EFI harnesses from the ’90s? Well MSD has reduced that bundle to this small harness. Beyond supplying a power source and a quality ground the remainder of the wiring is pretty much a plug-in operation.
The Atomic requires a trigger signal to operate. We were able to connect right to the tach output terminal of our HEI Distributor.