Retrofitting a ’72 Chevy with EFI
My ’72 Chevy project started way back in 1994. I’ve cut, chopped, fabricated, bolted, screwed, wired, and plumbed most everything myself while restoring and re-engineering my 4x4 pickup. One thing that has always stayed the same was some form of a naturally-aspirated carburetor on all of my engines.
In fact, I took the factory fuel-injection system off of the Vortec big-block Chevy I am currently running and bolted an intake manifold and 750-cfm carb on before throwing it in my truck. But, as most of you know, wheelin’ with a carburetor has its challenges. Some people have it worse than others, but in my case, I don’t think it could have been much worse. Not only did my motor sputter out or just not run on off-camber angles, but it would simply shut itself down if I went over any quick bumps off-road. I couldn’t even pop over a speed bump at the grocery store faster than 2 mph or I’d find myself cranking the thing over with my foot to the floor trying to start my flooded-out motor! After years of the same old BS, I finally decided to make the change.
I knew that fuel injection was the answer that would solve all of the issues I was having. My major hang up with retrofitting fuel injection, aside from the additional cost, has always been my fear of dealing with all of the electrical and computer hassles I thought would be associated with the swap. And I didn’t have a dyno to tune the truck on so I’d have to find a shop that could program the fuel injection as well. As it turns out, I was pleasantly surprised to find out that new self-learning EFI kits took a lot of the headches out of a retrofit.
When I started looking into various ways of fuel injecting my big-block, I stumbled across Holley’s self-learning Avenger EFI 4BBL TBI System. According to their instructions, this system included everything I would need to convert my carburetor over to a throttle body fuel injection system, and it claimed to be easy to install for anyone that could work their way around a tool box. They even offer it in three separate kits for engines ranging in horsepower from 400 hp to 600 hp. This sounded good to me. I am pretty decent at wrenching on just about anything on my rig, but wiring and computer stuff is definitely not my favorite subject.
My new Holley Avenger kit showed up and I couldn’t wait to dig into the box. As I laid out all of the components and briefly read through the detailed instructions, I realized how simple this install was going to be.
01. The kit comes complete with everything you’ll need except the tools and the fuel line you’ll need to plumb the system. It includes two different sets of instructions to guide you through the entire process of installing the kit. The first of the two is the hardware installation instructions. This carefully explains what additional items you will need to install the system, how to properly remove your existing fuel system, the tools you will need to complete the install, and step by step guidelines on installing each component. The second set of instructions deals with the initial start up after everything is properly installed and tuning the system once you are up and running.
02. A couple things stood out to me, like the fact that I needed to address my existing fuel tank. The Holley Avenger kit comes complete with the fuel pump, filters and everything you need except the fuel line itself to plumb your fuel system. The pump supplies fuel to the throttle body at high pressure, and the built in regulator returns fuel through a separate line back to the fuel tank. This requires a fuel tank with a return in it or you have to modify your tank to add one. My old ’72 did not have a return back to the tank so I decided to build my own tank and mount it behind the rear axle between the frame rails instead of modifying the existing one sitting behind my seat. Once I had it designed, I picked up aluminum plate from Industrial Metal Supply for my new 30-gallon tank and began to cut and tack-weld the shape together.