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MSD Atomic EFI On A Big-Block - Splitting The Atom

1967 Toyota Fj40
Harry Wagner | Writer
Posted October 11, 2013

Ditch That Carb

Wheeling has changed a lot through the years. Bigger tires, lower gearing, and fuel injection are mainstays nowadays. Electronic fuel injection (EFI) comes on every new vehicle, but that was not always the case. When we dusted off the family heirloom (literally) the first thing he wanted to add was MSD’s Atomic EFI. While fuel injection usually runs cleaner and generally delivers better mileage than carburetors, neither was the deciding factor for this upgrade. Our ’67 FJ40 is smog exempt, and it is a fool’s errand to expect the 468ci big-block under the hood (that’s right, I said big-block) to sip fuel with a massive four-barrel carburetor.

So what was the motivation? Fuel injection allows an engine to run at any angle on the trails, starts up easily, and automatically adjusts for different elevations and temperatures, unlike a stock carburetor. These situations are common to off-roaders and are on the radar for the Cruiser’s future. However, some fuel injection systems have a reputation for being complicated and difficult to install. All of that changed with MSD’s introduction of Atomic EFI. With half the connections of other systems, MSD claims that its product can be installed in a day. That may be true for a professional mechanic in a fully equipped shop, but could it be done by a couple of guys with basic handtools in a two-car garage? We wanted to find out.

The kit we ordered (PN 2900) is rated to support up to 525 hp and includes the throttle body, power module (with wide band O2 sensor), handheld controller, fuel pump, fuel filters, and all related wiring and hardware. If you already have an electric fuel pump capable of delivering the required 60 psi to the Atomic throttle body, a kit is also available without the fuel pump and is even easier to install. MSD engineers have incorporated most of the input sensors into the throttle body, which makes the system compact and clean-looking—perfect for our classic Land Cruiser.

1. The carb we pulled off actually worked rather well, with the biggest limitation being steep climbs and dealing with changes in altitude. These limitations are not unique to this carburetor but rather a limitation of most carbs.

The throttle body actually houses the ECU and incorporates the throttle position sensor (TPS), manifold absolute pressure sensor (MAP), intake air sensor (IAT), and fuel pressure sensors in one location on the right side of the unit. Also integrated into the throttle body are internal fuel rails that provide fuel to four 80-pound/hour fuel injectors, one at each corner of the throttle body.

Even with a few unforeseen challenges due to our unique drivetrain combination, we were able to install MSD’s Atomic EFI in a day at home in the garage. Once wired and plumbed the system fired right up and idled smoothly. With just basic input parameters and with the self-learning capabilities of the system, the throttle response and idle continue to improve with every mile we drive. We can now enjoy consistent fuel delivery at any angle on the trail and didn’t have to spend four years getting a degree in electrical engineering to do it.

Return or Returnless Fuel System?
Atomic EFI has the option to be installed as either a return or returnless fuel system. Returnless is the easiest to install because you only need to run a fuel line from the tank to the electric fuel pump and up to the throttle body. In contrast, a return-style fuel system uses a regulator and a second line running back to the tank with any excess fuel.

Several factors will help you determine which is best for you, including quality of fuel, ambient temperature, and distance of the fuel pump from the tank. While our parameters put us on the edge of the ability to use the returnless system, we chose it simply based on ease of installation with our existing fuel tank.

Adding a fuel pump in the tank and/or a return fuel line and regulator is more complicated. However, it will virtually eliminate the possibility of fuel pump cavitation (with symptoms similar to vaporlock) in hot conditions. If our installation creates issues in the future we will be certain to remedy the fuel routing and let you know.

Step By Step

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  • 2. MSD includes everything you need to complete the installation, from big parts like the throttle body to little parts like gaskets and wire loom.

  • 3. The only welding necessary was the addition of a bung in the exhaust collector to fit the included wideband O2 sensor. We put the sensor 3 inches after the collector at an angle of 10 degrees for condensation runoff, as specified in the directions.

  • 4. While the Atomic EFI includes just about everything you need for installation, we ran into a snag mounting the throttle valve (TV) cable for our 700R4 transmission. We were able to swing by Summit Racing Equipment’s retail location, which had parts from Lokar in stock to connect the TV cable to the throttle body.

  • 5. When we pulled a plug out of the intake manifold we found a little surprise waiting for us. This engine had been sitting for years and needed some help. The addition of Atomic EFI can’t work miracles, so we flushed the cooling system and changed all the fluids before continuing.

  • 6. The other part we purchased from Summit was a simple block-off plate to replace our old mechanical fuel pump. Atomic EFI requires at least 45 psi to run properly, and stock mechanical fuel pumps typically only produce around 10 psi.

  • 7. We mounted the included fuel pump along the framerail at the rear of the chassis near our rear-mounted fuel tank, and then ran the included EFI-rated soft line inside the framerail.

  • 8. MSD included fuel filters to mount before and after the fuel pump. We put the second filter on the firewall and then plumbed into the back of the throttle body, but there are provisions to plumb into the front of the throttle body as well. The flexibility came in handy for our custom application.

  • 9. The big-block already had a host of MSD components to fire it, including a 6AL ignition, a Blaster Coil, and a Pro Billet distributor that all date back at least 30 years and are still running strong.

  • 10. The MSD ignition had the provision we needed for a tach signal, but the instructions show wiring for use with stock ignitions as well. We did not use the Atomic EFI to control timing for this installation since we were trying to complete it in one day, but we have all the necessary MSD components to do so in the future.

  • 11. This is where we screwed up. By mounting the power module under the hood, we had to remove this vent to plug in the handheld controller. We will likely move the power module to the glovebox in the future, since the dash on the power module offers useful information about rpm, coolant temperature, fuel pressure, and more.

  • 12. After completing the installation we plugged in the handheld controller and referred to the instructions. Only general inputs like the number of cylinders are needed, and from there the Atomic EFI is self-learning. It runs better every time we drive it.

  • 13. There are three adjustment screws on the linkage. One adjusts the opening of the front throttle blades to assist with idle and tip-in. The rear blades also have a similar adjustment. These may require adjustment depending on your engine. There is one more adjustment that controls the front and rear throttle blades opening at the same time.

  • 14. Included in the kit is a flash chip that can be used to download updates from MSD and reload them into the handheld programmer. That way if MSD finds a way to make the system more efficient later on, you can benefit from those updates.

  • 15. With the K&N air hat installed it takes a sharp eye to even notice the change under the hood. That is part of the appeal on a vintage rig like our Land Cruiser.


Summit Racing
Akron, OH
Lokar Performance Products
Knoxville, TN 37932
MSD Performance
El Paso, TX 79936