Give just about any musclecar guy a carburetor, and he'll tell you how he could tune, rebuild, or modify it. Ask that same guy about fuel injection, and he'll start to stutter like a boy who just got caught stealing a cookie from the cookie jar. The truth is, there are a lot of confusing situations and misconceptions about EFI. One of the main reasons many people shy away from EFI is the tuning aspect. Let's face it, tuning an EFI setup requires a knowledge of ohms, impedance, timing, reading an air/fuel meter, and finally, a computer to program everything.
Why go through the hassle of installing fuel injection if your carburetor is working just fine? Having a well working EFI setup can make your Mopar so much more fun to drive-that's one. Fuel economy will also be improved, due to the EFI naturally metering the fuel by knowing what the engine needs at any given moment, via the O2 sensor-that's two. Finally, giving your muscle Mopar a modern fuel-injection system that looks like a carburetor is just plain cool-that's three. Yep, we said fuel injection that looks like a carburetor. Now, don't mistake this for a stock-looking, throttle-body injection system like a GM car might have. This unit looks remarkably like a performance carburetor, but with injectors hidden inside the false float bowls.
Adding the Retrotek injector/carb...
Adding the Retrotek injector/carb unit is as easy as replacing a square-bore flanged carburetor. If your carb is a spread bore-such as a ThermoQuad-you'll need an adaptor plate, like one from Mr. Gasket.
The company making this bolt-on-yes, we said it-kit is Retrotek Speed located in Corona, California. The kit functions with the use of some key components. First are the injectors. Standard Bosch "port"-style injectors are used and are basically worry free. The big item on the list is the Engine Management System (EMS), which controls everything. In order for the EMS to know what's going on with the engine and what its needs are, the EMS relies on three input signals. One is from the Coolant Temperature Sensor (CTS). the computer needs to know what the engine coolant temperature is so it's able to regulate the fuel requirement for efficient operation. The second input is generated by the Manifold Absolute Pressure (MAP) sensor. This sensor takes a vacuum (or boost signal in supercharged applications) and turns it into an electronic signal. The computer uses this vacuum-converted electronic signal to measure the load on the engine. This allows the computer to adjust the ignition timing-advancing it and retarding it as needed. It performs essentially the same job as the vacuum advance diaphragm on an old-fashioned mechanical distributor. Finally, the Throttle Position Switch (TPS). The TPS is mounted on the throttle shaft of the "carburetor" body and changes resistance as the throttle opens and closes. The computer uses this information to monitor engine load, acceleration, deceleration, and when the engine is at idle or wide open throttle. The sensor's signal is used by the EMS to enrich the fuel mixture during acceleration, and to retard and advance ignition timing. Ok, we told you the basic parameters of what the system is, but how easy is it to install and how does it work?
Ease of installation is dictated by which kit your engine needs. If you are building an engine with more than 500 hp, you need to add more plumbing for the return line. If your engine is making less than 500 hp, you will be able to use the return-less system. The hardest part of the install is making the final decision of where to mount the external fuel pump, the EMS unit, and the fuel filter. Other than that, it is literally plug and play.
Looking at the underside of...
Looking at the underside of the unit, you can see that four high-impedance injectors are mounted directly over each butterfly. You can also see the fuel inlet plug on the side of the "fuel bowl." The Retrotek kit features available fuel inlets on each side of the unit for different applications.
The Dart Sport already uses...
The Dart Sport already uses AN-style fittings, and the hose simply connects. If you are not using AN-style hoses and fittings, a standard 9/16-24 fuel feed line will work.
The linkage all connects just...
The linkage all connects just like a carburetor.
Before you mount the EMS controller,...
Before you mount the EMS controller, run your wires through the firewall and make your connections at the engine. Retrotek recommends that you DO NOT cut or shorten the wires for the kit.
The great thing that the Retrotek kit has over other aftermarket EFI kits is its ability to "learn" the engine it's mounted on. The "Smart Tune" technology will learn the engine's needs within a couple of days driving, and it's also completely tunable if you're one of those guys that can't keep your hands off things.
The system as installed on our 360-powered Dart Sport was a bit on the rich side. The unit seemed to work ok, but you could tell that the setting was rich. the guys at Retrotek Speed designed the initial program to run a little fat because it saves people from ruining a perfectly good engine by running it overly lean. Once we got a few small details worked out, it was fine.
The small details were in no way a reflection on the Retrotek kit. In fact, the guys at Retrotek were more than helpful over the phone when we had problems. So, if you want EFI for your Mopar, and you want it to resemble a stock carbureted system, look no further than Retrotek Speed for what you need.
All engine connections are...
All engine connections are marked on the harness and simply plug in (TPS shown).
The heart of the return-less...
The heart of the return-less system is the fuel regulator, which is self-contained within the front fuel bowl. Again, simply plug in the proper connector.
Next, the Coolant Temperature...
Next, the Coolant Temperature Sensor. Our intake did not have enough ports in it to mount the sensor, so we had to tap a hole to fit. When drilling the hole, it's a good idea to put some hard grease on the drill flutes. This will keep the majority of the metal shavings from entering the cooling system and flying all over. Same goes for tapping the threads.
After threading the new hole,...
After threading the new hole, the CTS was installed, and the proper connector plugged in.
The MAP sensor (arrow) needs...
The MAP sensor (arrow) needs to be mounted as close to the engine as possible to reduce the length of vacuum hose required.
Speaking of the vacuum hose,...
Speaking of the vacuum hose, the map sensor uses a 3/16-inch inner-diameter hose, and the other end connects to the bottom nipple at the front of the EFI unit. After the install, we moved our MAP sensor to the underside of the air cleaner, which not only hid it, but also made the hose shorter, giving a quicker response.
Do not try to run your EFI-pumped...
Do not try to run your EFI-pumped fuel through a mechanical pump. You will need to remove the pump and install a block-off plate.
To mount the O2 sensor in...
To mount the O2 sensor in the exhaust pipe, you will either need to weld an O2 bung onto the pipe or use the available Retrotek clamp-on bung. Either way, you will need to drill a hole in the exhaust pipe. Even if you have a dual exhaust, the Retrotek kit only utilizes one O2 Sensor.
After we had the sensors connected,...
After we had the sensors connected, it was time to determine a good location for the EMS box. Since the wiring was long enough, we decided to mount ours under the passenger seat because the firewall area was already cluttered with the heater box and other things. When we mounted the box, we used a set of ignition box mounts that raised the box about 1/2-inch off the floor. This allows air to pass over and under the box to help keep it cool.
The fuel pump is a Retrotek...
The fuel pump is a Retrotek specific unit. for a pre-pump filter, we went to our local auto parts store and simply got a carburetor useable filter with two nipples on it for the rubber hose connections. After the pump is the EFI rated filter. Retrotek recommends mounting the pump in a location close to the tank and below the fuel level.
In our A-Body, we found it...
In our A-Body, we found it impossible to mount the pump below the tank level, but we did mount it as low as possible, and it is lower than the sending unit connection. The wiring comes from the EMS bulk connection and is coded for a proper connection.
Many issues with electronics...
Many issues with electronics can be traced back to a bad ground. The Retrotek kit has a preterminated end that must be properly grounded. We attached ours to an intake bolt on the passenger side of the engine; the negative cable from the battery is attached to the driver side of the engine.
The final electrical connection...
The final electrical connection is for the power supply. One wire gets connected to a constant 12-volt source, and the other to a switched source.
The one issue we did run into:...
The one issue we did run into: our air cleaner had a drop base and wouldn't fit over the Retrotek EFI body. You can either use a spacer like we did or change to a no-drop base air cleaner.
We hooked our laptop to the...
We hooked our laptop to the car just to see what the EFI was doing. the dashboard that the kit displays is remarkably informative. At 60 mph in high gear, you can see that the air fuel reading is right at 13.4. Nothing wrong with that. The dashboard also shows engine vacuum, fuel pressure, and just about anything else you want to see.
Well, we're car guys and couldn't...
Well, we're car guys and couldn't leave well enough alone, so we tuned a bit more. The Retrotek kit is shipped with the A/F settings a little rich. This isn't bad because it means you won't hurt your engine, but you can tune for better mileage if need be. After driving the car on the highway for about 45 minutes with the laptop hooked to it, the adjustments were made.
Once the install was finished,...
Once the install was finished, it looked remarkably like a standard carbureted setup . . . if you can ignore the few extra wires.