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Putting The Easy EFI Swap To The Test

Passenger Side Wiring Harness
Cole Quinnell | Writer
Posted October 1, 2012

One Day EFI

Bigger, better, faster, and it will make you better looking! We’ve heard a lot of promises and claims in our time, and most of them we go by without the slightest temptation. But when MSD launched its Atomic EFI, claiming to make electronic fuel injection (EFI) conversion easy and fast, it got our attention.

In the past couple of years, there have been a few EFI systems introduced that promised easy installation and laptop-free tuning. In fact, they claim to be self-tuning. These are throttle-body-based systems, bolting on in place of a four-barrel carburetor. They don’t have to control the ignition system. And they don’t require a degree in air/fuel ratio technology to tune. All of that sounded too good to be true, so we decided to put one of them to the test.

If you’ve been around older 4x4s with carburetors for a while, you’ve probably toyed with the idea of swapping to EFI. The idea of a fuel system that runs at just about any angle without hiccups when your rig is bouncing all over the place is pretty appealing. But the cost, complicated installation, and laptop tuning are enough to keep most people tinkering with the 30-year-old carbs.

Self-learning systems like the Atomic EFI use an oxygen sensor to constantly monitor the air/fuel ratio in the exhaust and quickly adjust the fuel delivery to balance the mixture. Instead of a complicated fuel map (and equally complicated ignition timing map), these simplified systems give you the ability to increase or decrease the target within a specified range. And you do so through a handheld controller. With the Atomic EFI, you answer a few questions about the engine before you start it the first time, and the system will set itself close enough to start. In some cases, you won’t have to do any tuning at all.

The key to a simple install is that the Atomic EFI is a throttle body system, not a multi-point. Some people will point out that a throttle body gives up some efficiency compared to a multi-point system, and that’s true. But the ability to leave your existing intake in place makes the installation much easier, and tuning the system is also easier.

The Atomic EFI system can be used with or without a fuel return line. Most EFI systems require a return line, sending excess fuel back to the fuel tank. The fuel pump included with the Atomic EFI master kit can be pulsed. If you’re not using a return line, the electronic control module (ECM) pulses the pump to manage fuel delivery. However, if your 4x4 is susceptible to vapor lock (the fuel vaporizing in the fuel line because of excessive heat) you should add a regulator and fuel return line. Keeping the fuel moving through the lines allows it to stay cooler and avoids vapor lock.

You can order the system with a fuel pump, fuel filter, and high-quality fuel line (part number 2900) or without (part number 2910). The master kit is about $300 more than just the throttle body kit, which may seem a bit pricy for what you get. However, it can be mounted inside the fuel tank or out. If you know you’re going to run a return line and mount the pump outside the fuel tank, you can order the Atomic system and get a 60 psi inline fuel pump that moves 43 gph at 12 volts, such as the Walbro GSL392 from Summit Racing for about $115. You’ll also need a fuel filter rated for use with EFI, fuel line, regulator, clamps and fittings, which will bring you to about $300.

There are three things we recommend doing ahead of time to make sure that you can successfully go from a running carbureted 4x4 to a running EFI 4x4 in the same day. First, build the new fuel system. We’d even suggest installing it and just not making the final connections. This is especially true if you’ll use AN hose and fittings which can send you hunting for hard-to-find ends and adapters. Even with a bucket of AN fittings, we still had to place three separate orders to get everything we needed. Next, read the instructions and make sure you and your vehicle have everything that will be needed. For example, we found that we needed to upgrade our GM HEI with an aftermarket module to provide the proper tach output to the Atomic EFI. That would have been a deal killer if we hadn’t read the instructions in advance (see, they are good for something). Finally, have the oxygen sensor bung welded into the exhaust pipe. MSD provides a plug for the fitting, making it easy to get this done in advance, plug the hole and drive for as long as you need to before installing the EFI.

Taking these steps, we were able to convert a carbureted V-8 to the Atomic EFI in just a day – one person working 10 hours to be exact. We’ve driven the vehicle for a bit since the install and found it worked really well right out of the box. We didn’t have any stumbles or bogs, and the engine ran well at angles as well as over bouncy terrain. Basically, we found that the system lives up to claims—it was easy to install, runs better than the carb, and we’re better looking!

Time It Takes
3-4 hours to install fuel system:
45-60 minutes to install HEI ignition module
30 minutes to remove carb and install throttle body
2 hours for wiring
8-10 total hours for complete install

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Better Fuel Line
If you’ve noticed the smell of fuel in the garage around your modified 4x4, you’re not alone. Today’s fuel is very aggressive with more additives and ethanol than we’ve ever had before. This fuel can seep through old-school rubber fuel line and braided steel hose, leaving a smell of raw fuel in a closed area. But it’s more than an irritating smell; the fuel causes quicker deterioration of these old hoses.

We ran across a company that makes a product just for our market to address this issue. The TechAFX BlackWrap fuel hose has a polytetrafluoroethylene (PTFE), conductive-core inner liner that is made to work with today’s fuels. BlackWrap has an industry-first, black polyester outer covering applied over braided stainless steel to create an impact-resistant all-black hose. That means an abrasive-resistant outer layer, composition to resist the deterioration caused by modern fuel, and conductive core that eliminates the risk of static electricity buildup in the fuel line. A win-win-win.

Sources

Aeromotive
Lenexa, KS 66214
913-647-7300
www.aeromotiveinc.com
TechAFX
West Bloomfield, MI
248-925-8314
www.techafx.com

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