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.
Next up was the fuel supply system. Once again the MSD Atomic EFI Master Kit was all inclu
Our next project was installing the MSD Atomic fuel pump and filter, which came with our complete kit. Also included in the kit was flexible hose rated for the higher (45 psi) pressure required for EFI. It should be noted that 100 percent hardline isn’t recommended for this installation as the flexible line helps absorb the pump pulsing. Of course there’s always a need for a flexible connection from the chassis to the motor, regardless of the induction system.
We found a suitable location for the pump under the car and slightly below the level of fuel tank. After safely draining and containing the fuel, the lines were cut and the pump was spliced into the feed. While there is an option for a single fuel line, we opted to run a return line back to the fuel tank, making our system a recirculating system. The constant recirculating fuel provides a cooler fuel.
Hot Rods by Dean mounted the pump on a small plate and used the pump and filter connection
The power for the fuel pump comes from the MSD Atomic Power Module so wiring and control is simple. There is also no need to install a pressure gauge as the supplied handheld controller enables you to adjust the fuel pressure electronically, how cool is that?
At this point we had the Atomic EFI system installed. A quick check of the fuel lines and wiring and linkages indicated we were ready to fire up the small-block. The battery was reconnected and we answered some very basic questions on the handheld controller. Then the key was turned on, the fuel pump powered up, and with a twist of the key the 350 fired to life and settled into a smooth idle. At this moment it is easy to become a believer in EFI. Because the MSD Atomic Fuel Injection is a self-learning system the need for fuel map tuning and throttle configuration is eliminated. There are advanced tuning capabilities built into the handheld controller, but for many street rodders the self-learning mode is as far as they go.
With the unit installed we can see the supply from the tank and the fuel exiting the filte
The MSD Atomic EFI does have some limitations. The unit is designed to operate engines producing more than 100 and less than 525 hp and the Atomic EFI unit will not work on dual-quad applications. Likewise the unit is designed for modern-day pump gas so alternative fuels and power boosters will not work with the throttle body.
The MSD Atomic EFI has the ability to control timing but it requires an MSD Ignition Control. Since the Atomic EFI does not have a built-in ignition driver your points or HEI distributor will require ignition box for the EFI to operate. The Atomic requires a trigger signal from the ignition in order to function. This can come from the tach output of a GM HEI distributor, most coil negative terminals, or from a 12V trigger source such as the tach output from a typical CD ignition control. In order to control the ignition timing through the Atomic, you would need to run a CD ignition control such as an MSD 6A.
The final connection is made at the EFI unit. Flex line from the chassis to the motor is a
While the MSD Atomic EFI can literally be installed in an afternoon, we’d plan on making a weekend conversion out of the job. Something we have become adept at lately is taking an afternoon job and squeezing it into a weekend. But regardless of whether you are quick enough to do it in four hours or twelve, the results are well worth the effort. Quicker starts, smooth idling, superior driveability, mileage, power, and cleaner emissions add up to huge improvements, making this one of the best modifications anyone can make to a street rod. Now follow along with the photos and we’ll show you how it’s done.
There are ample vacuum ports made available on the Atomic EFI, up front we used the large port for the PCV hose, while the smaller hose on the left controls the vacuum advance on the distributor.
The PCV hose was gently touching the throttle return spring so the guys at Hot Rods by Dean came up with this clever Ty-wrap bracket. A large wire end bolted to the EFI base does the trick.
The temperature sending unit was next up and once again a plug on the wiring harness simply plugs to the sensor.
Speaking of wiring, here is the wiring diagram from MSD, it illustrates just how simple the electrical portion of this install really is.
The only fabrication involved was installing the bung for the O2 sensor (some headers have this on the collector already). After a pilot hole, the step drill does a nice job of cutting a round hole.
The bung was TIG welded in place and you’ll note that the sensor is located on a straight portion of the tubing. This is important for correct readings, likewise be certain you have no exhaust leaks upstream of this sensor.
Once again the O2 sensor simply plugs into the supplied harness with the weather-tight connector.
The Atomic EFI comes with a short cable from the power module to the handheld unit so you can do the basic setup function on the fender.
However with the optional long extension the handheld unit can be used inside the car, this can be handy for advanced tuning, although many street rodders simply set the basics, set it and forget it.
The initial setup asks some basic questions about the engine and transmission. If you can read this story you can set up the Atomic EFI. You can adjust everything from fuel pressure to a rev limiter in the basic format.
There are advanced settings and a troubleshooting screen all on the handheld device; this is a very user-friendly system.
The 10,000-Mile Testimonial
Jim Shelton has driven just about every type of car a guy could imagine in his 71 years, and his latest ride of choice is a very traditional Deuce roadster that has logged 90,000 miles in just under 10 years. One look at the burgundy hot rod tells you Shelton is a traditional kind of guy, and frankly he was a pretty healthy skeptic of this new-fangled EFI stuff, but rather than try to interpret Shelton’s testimonial we’ll simply let you hear it directly from Shelton himself after one of his little 8,000-mile treks:
Jim Shelton has logged over 90,000 miles on his roadster, and while he was a bit of a skep
“The odometer read 89,450 miles when I arrived home and I had covered 20 states in my 47-day odyssey. The MSD Atomic EFI performed flawlessly. I admit I was skeptical of what MSD said about the Atomic EFI. My understanding of EFI was anything short of port injection wasn’t worth the hassle and this was a throttle-body system. However, the idea of a hot rod running well in any temperature, at any altitude was enough for me to take the gamble prior to my 20-state journey.
“Smokey Yunick I’m not, so I enlisted the help of my good friend ASE Master Tech Scott Gafforini to help with the installation. I don’t regret it, but it was probably overkill on my part. The throttle body directly replaces the carburetor and the power controller mounts with a few screws, and while we had to connect a few wires, for the most part it was plug in. I can use a computer to send an email, but the thought of using one to tune an engine terrifies me. No worries there. A handheld device temporarily plugs into the Atomic EFI power controller to set a few major parameters. The engine fired instantly and settled right into a comfortable idle. I can’t comprehend how but the system’s self-learning mode fills in the gaps. Since that initial setup I have used the handheld controller to change the temperature the cooling fan comes on, altered the cruise air/fuel ratio, and dropped the idle speed, all by pushing a few buttons.
Under the hood of the Shelton roadster the EFI goes virtually unnoticed. The original carb
“This was a gamble that really paid off. The engine starts and idles regardless of temperature. It doesn’t pop or sneeze if I drive it cold and I can pull into traffic without praying the engine won’t stumble or lurch. It runs beautifully at the beach or going through Eisenhower pass. The wide-open throttle response is the same as the carburetor, but the midrange response improved so much you’d swear it was a bigger motor, all that and a 15-20 percent improvement in gas mileage. The roadster drives even more like a modern car now. The highest elevation covered was 11,100 feet at the Eisenhower Tunnel in summertime temperatures. The next highest was 10,700 feet heading into Wyoming. Coming down the north side I drove into a snowstorm so the unit endured all kinds of weather.
“I have high expectations of how any car, even a raucous hot rod, should drive. I began with a high-end carburetor that underwent hours of tuning and I dramatically improved the performance with the Atomic EFI. My fears were unfounded; this was far easier to tune than any carburetor. Twenty states and 10,000 miles later I’m still surprised at how much I like this system. Goodbye jets and power valves.”