From Trips to Trick

Swapping a trio of drippers for multi-port precision

Story Andy Bolig images provided - November 27, 2013 10:00 AM


1 We’ve enjoyed the trio of carbs but wanted more out of a tank of fuel. Being a driver, we were simply upgrading the fuel supply. The Avenger EFI unit was well up to the task. 


2 Multi-port units can either fit early or late-style SBC bolt configurations or, you could opt for the two- or four-barrel versions to fit on a myriad of other intakes. 


3 The two-piece StealthRam intake consists of a lower portion and an upper plenum. New gaskets and making sure everything seals properly will ensure optimum drivability. 


4 The multi-port units come with 36-lb injectors for up to 500hp in the small-block and 48-lb injectors for the big-block version, which will handle up to 1,000hp. 


5 The plenum and throttle body are mounted on the intake base. The IAC (idle air controller) and the throttle position sensor also get mounted. They work with the computer to bring control to the engine’s operation. 


6 All necessary sensors are supplied in the kit. Even items like engine coolant temperature will dictate the fuel demand of your engine. 


7 Our engine already used a PerTronix distributor. For those who wish to upgrade their install to include timing control, a later-style GM distributor could be used with the Holley EFI system.


8 EFI systems run at higher pressures than carbs. A new electric pump is supplied and a new return line will need to be devised. There are several options listed in the instructions.


9 To keep the fuel system clean, filters are supplied for both the low- (pre-pump) and high-pressure fuel lines. 


10 The heart of the system is the computer. There are two sealed, main connections which simplify the install and the ECU can be mounted inside the cabin or out, under the hood. 


11 With the hard bits addressed, it was time to attack the wiring and various hoses and fittings. Systematic placement of wires and hoses and adherence to the instructions will ensure long life and enjoyment. Follow the instructions and you’ll be enjoying your EFI in no time!   

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If this is the first time that you’ve heard there are benefits to be had for converting old carburetor(s) over to electronic fuel injection, welcome to planet Earth. On the other hand, you may not be aware of exactly how easy such a swap has become. 

You are no longer required to possess a Ph.D. to make these new-fangled fuel systems perform correctly and the vast extent of options available to the enthusiast now covers the horizon from “mild-to-wild”. 

Just like in any computer, improvements have come about in almost exponential proportions as processor speed and capability have brought even more benefits to the enthusiast. The more closely you can control an engine’s operation, the more you can capitalize on getting optimum performance and drivability from it. The trick for so many enthusiasts was getting all the benefits contained within that little box without donning the pocket protector and wide-rimmed glasses. 

Holley has been building fuel meters since 1903 and rather than bury their heads in the sand and stick to only building (or re-building) carburetors, they have decided to evolve with their own version of electronic fuel injection. EFI has been around long enough that many companies offer systems that will make an engine run. The hard part is making a system that does so, yet can be both simple enough for the “everyman” to make use of it and versatile enough to fit many applications. 

Wanting to make their system end-user friendly, Holley has designed their EFI as a simple, complete unit that offers all the necessary items for installation. They also use the newest wide-band oxygen sensor technology and a self-tuning capability that constantly keeps the engine’s diet of fuel in the highest level of performance and fuel economy. 

Attending ANY car show will instantly reveal that there are millions of different applications that might benefit from a modern EFI system. Making a system that meets as many of those applications as possible isn’t quite as obvious. Holley’s answer is to offer several different versions of their EFI, ranging from simple two- and four-barrel TBI installations, all the way up to a power-adder capable, electronic transmission shifting/throttle controlling monster they call the Dominator. If you are retrofitting a modern engine into a vintage ride, Holley also offers various EFI units designed to control these even more complex configurations. 

Upgrading from a carb to EFI can easily be done with their Avenger EFI. Even so, you can choose between the aforementioned TBI units or go with multi-port fuel injection via a four-barrel throttle body or Holley’s hyper-intimidating StealthRam intake, sporting dual 58mm throttle blades. We decided to install the StealthRam, which will easily handle our 475-horse 383 small-block. Another benefit of going with a Holley EFI, you can also control the spark timing of your engine to help prevent damaging pre-ignition and tune for optimum power through the keyboard, rather than weights and springs deep within a distributor. 

If you are looking at installing a power-adder or wanting more control from your controller, you can easily upgrade your Avenger to Holley’s HP unit capability. That would give you boost and nitrous control capabilities, as well as data logging and a wider range of tuneability, to bring those wilder engines into supreme usefulness. If you are willing to jump into the even deeper waters of control, you can opt for the big-dog of Holley’s EFI — the Dominator. Here you will not only get all the benefits of fuel, throttle-body, power-adder and timing control, but you can also give orders to an electronic transmission. This truly opens up a new world to your vintage auto and gives a decades-old driver all the characteristics of a more modern fuel-miser. 

Even with the broad spectrum of offerings for EFI, one of the benefits of the Holley system is the pre-installed tuning that requires only input of parameters specific to the engine being operated (displacement, cam specs, power-adders, etc.). Once the controller has an understanding of the engine it is deemed to control, it can utilize the information and create a tune that will have your engine up and running in no time. Then, with the additional interface, or through your laptop, you can then continue to tweak the tuning to bring the fuel feeding of your engine to an optimum state for power, efficiency and driveability. We did a 2,500-mile drive on an 860-horsepower, 555-cubic inch BBC equipped with a Holley Dominator ECU, running with minimal tweaking from the supplied tuning. Those 860 horses were dyno-proven and the engine’s diet of fuel supplied a 16 mpg average during the long-distance haul, without the help of an overdrive.

The installation of the Avenger system on our ’70 Chevy truck was pretty straightforward. It was already a driver, so upgrading to EFI was done with a minimal amount of troubleshooting and engineering. There are a few things to note as you install any EFI. Since the system works on electronics, you want to be sure that the system gets adequate voltage supply from the battery and that all connections are good and secure. Chasing intermittent shorts and open circuits can easily dim the shining benefits of EFI.

Also, you will need to supply a route to return the unnecessary fuel back into the fuel tank. Other than these considerations, the install is pretty straightforward and well within the realm of the average enthusiast, even if the benefits are well beyond those available with a carb, no matter how many you might have under the hood!

For Your Information:

Holley, (270) 782-2900,

PerTronix, (909) 547-9058,