Words and Photos by Jeff Smith
All the fuss over quick-swap throttle body EFI conversions tends to overshadow one of its primary benefits. The original and still the best idea is to place an injector directly over each intake port and then sequentially time the fuel to arrive just before the intake valve starts to open. This eliminates the issues of wet-flow intake manifold attempts at compensating for fuel that has a bad habit of going where it wants — instead of where it’s supposed to go. This leads to rich and lean cylinders and less than ideal performance.
Edelbrock knows all this, of course. They’ve been in the intake manifold business longer than anybody else. Their most recent development is dubbed the Pro Flo 3, a complete multi-point EFI system that employs preassembled injectors, fuel rails, sensors, and throttle body, all mounted on an Edelbrock EFI single-plane intake manifold. Add in a highly accurate optical sensor distributor and complete sequential control over the fuel and ignition system and that adds up to a great system. Then, Edelbrock spiced it up with a wireless Android tablet that puts you in full command of a very sophisticated EFI package.
Just like many of the other self-learning systems, the Pro-Flo 3 takes basic engine inputs to create a
beginning fuel map and then uses the included wide-band oxygen (WBO2) sensor as feedback to learn the minor tuning details to adhere to your specific engine’s needs. You tell the system your desired idle, cruise, and wide open throttle (WOT) air/fuel ratios, and the system learns and applies all the in-between details.
Something this highly developed demanded more than just a cursory overview. The best way to do that was actually install the system and then do a firsthand evaluation. We talked with Edelbrock’s Eric Blakely and scheduled a time to take our ’65 El Camino down and install it right on premises. That doesn’t mean we couldn’t have done the job in our shop, as the swap went very smoothly. Our real reason was more pragmatic — they had more room in their shop!
We had a slight advantage over perhaps a first-time installer because we had previously installed a couple of competitive self-learning systems, which required a proper high-pressure fuel delivery system. This is a critical step toward any successful fuel injection system. The best choice is an in-tank pump with some version of either a fuel reservoir or fuel pickup system in the tank that is not subject to uncovering the pickup due to sloshing fuel. Our choice was the Aeromotive Phantom system using Aeromotive’s Stealth 340 pump that offers more than sufficient fuel volume and pressure to feed our mild little small block.
With that accomplished, the next step was to remove the existing Edelbrock carburetor and Performer RPM dual-plane intake and MSD distributor. We would not be re-using any of these parts. Spearheading our installation was Edelbrock’s David Shaw. The Pro-Flo 3 system comes with the fuel injectors, fuel rails, throttle body, and the coolant sensor already assembled, so all we had to do was perform the intake swap.
We also wanted to use the Pro Flo 3 ECU to control our two Spal electric fans, which required adding two small white wires to the harness. Fan 1 connects to the position shown with the arrow (pin 16), while the second is the very last pin position. Reading the instructions, we learned there’s a plastic lock that must be released to push the pins in place and then relocked.
Shaw cleaned the old gaskets and replaced them with Edelbrock gaskets from the kit. Our engine was equipped with Vortec heads, which use a specific intake bolt pattern, but that was the only change from a typical small-block Chevy. Shaw had previously set the engine at 10 degrees before top dead center (BTDC), so once the intake was back in place, he dropped in the distributor and lined up the rotor pointing to the stamped “1” in the distributor body. This ensures the timing will be close. We also plugged an open coolant hole in the front of the manifold with a pipe plug.
The most time-consuming effort to installing the Pro-Flo 3 system was simply executing where to mount the ECU and how to route the wiring. We decided on a position in the front left corner, using an aluminum mount for a fan controller that we no longer needed because the Pro-Flo 3 would control our twin electric fans. We mounted the ECU and then routed the wires underneath the fender to camouflage as much as possible.
Before we routed the harness, we had to relocate the ignition coil, since there was no provision for a coil on the intake manifold as before. We found a simple coil mount bracket that allowed us to mount it to the back side of the driver side cylinder head. Originally, we routed the two orange and black wires from the MSD to the coil alongside the ECU wiring. But later, we decided this might cause interference with the ECU and re-routed them to the coil around the passenger side, to maximize their distance from the ECU. We did not have any problems, but we thought this was still a good idea. The MSD (or any CD system) shoots 500 volts through these wires to the coil and can cause interference problems if bundled with the main wiring harness.
The Pro-Flo 3 does not require a CD ignition box, however. A separate ignition harness that will connect directly to the coil is also included. This system uses the optimal trigger in the distributor to send a signal to the ECU, which then drives the coil with an internal module similar in process to what is used in an HEI distributor. This makes for a very compact, yet simple inductive ignition system.
With the distributor and coil mounted, we moved to the fuel delivery side of things. Edelbrock sets the manifold up for a single feed into the fuel rail on the passenger side. This interfered with our fitting for the heater hose. We could have relocated the fuel inlet to the rear of the manifold, but the cross-over hose didn’t fit as well in the front, so we elected to move the inlet to the driver side. There is a schematic in the instructions that indicates you must use a return-style regulator, but one was not included in the Pro-Flo 3 kit. Most EFI-style return regulators have a fuel inlet on one side with regulated pressure on the opposite and the return on the bottom. This is how we configured our regulator.
We had also previously installed a WBO2 in the exhaust, so that made adding this sensor a matter of merely bolting it in place. As a suggestion, performing all the ancillary jobs like adding the fuel pump and the return fuel system, along with the WBO2 sensor, are all projects that can be done before actually installing the EFI system. This will make the final part of the project move much more quickly.
With all the connections completed, we double-checked our hose connections, refilled the coolant, and we were ready to fire the engine. This is when we followed the Edelbrock instructions to configure the software package for your particular engine. Using Setup Wizard in the supplied wireless tablet, we plugged in all the details for our engine, including displacement (350c.i.), camshaft profile (mild 210-230 degrees), 58 psi for fuel pressure, 29 lb-hr injectors, and the manifold Pro-Flo 4150.
We had already hooked up a timing light and were ready to start the engine, but we discovered it wouldn’t fire. A quick check with the timing light determined we had no spark. That quickly led to discovering we had relocated the switched power connection for the MSD, but it was not hot during cranking. We quickly rectified that situation back to its original harness connection, and the engine immediately started up and idled.
The next step was to set the base timing at 12 degrees BTDC. This is done by using the tablet to lock the timing so the distributor can be adjusted to indicate a base timing of 12 degrees BTDC on the harmonic balancer. This confirms that all timing commands from the ECU will be what the engine actually experiences.
With that accomplished, we then set the idle speed target at 750 rpm and adjusted the idle speed screw on the throttle body until the idle air control (IAC) percentage was at 10 percent. This was extremely simple compared to far more complex adjustment procedures we have experienced on some of the less expensive throttle body systems. After the TPS was calibrated, this completed the setup, and we were ready for our test drive.
Once the engine was up to operating temperature, we noticed a slight hesitation just off idle when we let the clutch out on our four-speed, 3.08:1 geared combination. We added a couple of points of acceleration enrichment, which helped, but didn’t quite eliminate the problem. We spoke later with Edelbrock engineer Mark Honsowetz who said our engine application is their most popular, with excellent feedback from early customers. He said it’s possible that sometime during the learning process, the system may have suffered a learning hiccup. His suggestion was to reload the system and try it again. We did, and this basically eliminated the off-idle lean stumble. This made sense because early on, the system ran really great.
But even before we made those changes, it was immediately apparent with our first test drive that the engine just felt better and seemed to respond very quickly to throttle. But more than anything, the engine just felt smoother. A friend went for a ride with us the next day, and he also commented on how smooth it was running.
While there are probably lots of theories, we attribute this to the fact the injectors are now located directly over each intake port, along with the inherent advantages of sequential or timed injection. Early multi-point injection systems from the ’80s used what is called batch injection, where the injectors fire in batches. Sequential fuel injection is also called timed injection, where the injector fires just as the intake valve opens. There are no real power benefits to sequential over batch, but there are some small gains to be had with throttle response and drivability, which is what we noticed through the seat of our pants and plenty of time behind the wheel.
Another side benefit we really haven’t mentioned much is the wireless Android tablet that’s part of the system. Not only is it handy to have a large, full-color screen to look at and use as a digital gauge package, but it’s also pleasant not to be tethered to the car. The system has sufficient signal strength to allow you to walk a few feet away from the car and still monitor or input changes to the system. Blakely also mentioned that if you already own an Android tablet, you can purchase a Pro-Flo 3 without the tablet and easily upload the software.
If your car is not set up for EFI with a fuel delivery system, adding that could add a day or so to the time required for installation. We spent a couple of days performing our installation that, for once, was not in thrash mode. We took our time installing this system, so it took longer than it should have because we did not rush and make a mistake. Except for the hiccup with the switched power, it all went very smoothly.
We’ve already put about 500 miles on the system, and compared to all the previous self-learning EFI systems we’ve played with, the Pro-Flo 3 has to rate right up near the top for ease of installation (if you don’t count installing the manifold), minimal tuning, and overall drivability and performance. We’ve already decided this is a keeper system. It will be a hard sell for anyone to convince us to remove this Pro Flo 3 in lieu of something better. Why mess with success?
Idle Vacuum Settings
The cam timing input in the early configuration asks for the duration numbers. If you are not sure of the numbers, this chart lists idle vacuum ranges for each of the three different cam timing areas. The Mild Cam is by far the most popular.
Configuration Idle Vacuum (inches of Hg)
Stock Camshaft: 15 to 20 inches
Mild Camshaft 10 to 16 inches
Race Camshaft 8 to 11 inches
|Edelbrock Pro Flo 3, std 550 hp SBC, satin||3220||Summit Racing||$2,995.95|
|Edelbrock Pro Flo 3, std 625 hp SBC, satin||3221||Summit Racing||$2,995.95|
|Edelbrock Pro Flo 3, Vortec 550 hp, satin||3225||Summit Racing||$2,995.95|
|Edelbrock Spark plug wires, universal||22711||Summit Racing||$65.99|
|Edelbrock EFI return fuel pressure regulator||174043||Summit Racing||$164.32|
|Russell EFI fuel filter, 10 micron, black||649250||Summit Racing||$79.97|
|Edelbrock 14” chrome air cleaner, cotton||1224||Summit Racing||$45.49|
|Russell Wrap-It over-sleeve,15/16”||629090||Summit Racing||$26.97|
|Russell Wrap-It over-sleeve,3/4”||629150||Summit Racing||$34.97|
|Aeromotive Phantom 200 lph fuel pump kit||18689||Summit Racing||$459.97|
Sources: Aeromotive, aeromotiveinc.com; Edelbrock, edelbrock.com