Getting vertical seems to be all the rage these days when it comes to hard-core rockcrawling. While I've stepped away from the momentum-infused rockracing competitions, I still enjoy the thrill of extreme rockcrawling. These days, that means attempting obstacles that are similar to, or were part of, former competition courses. In order to hang in the shadow of the current big dogs, my old Jeep, the dinosaur-tech Killer Bee, and its equally antiquated owner (me), have had to ditch the carburetor and step up to the marvels of electronic fuel injection.
The Bee's ZZ4 350 crate motor is designed to run a carburetor, and Chevy claims it cranks out 355 hp and 405 lb-ft of torque with one attached. I didn't want to lose those numbers, so I wanted a system that was compatible with my existing cam, heads and other engine internals. In talks with Edelbrock's tech department (800/416-8628), it was recommended I go with the two-barrel (750-cfm) Performer Pro-Flo system. (The company also offers a four-barrel system, and Pro-Flo kits for big-block Chevys and small-block Fords.)
Edelbrock's Pro-Flo EFI systems come complete with everything needed to convert your carbureted small-block Chevy to EFI. This includes Edelbrock's own calibration module, which plugs into a phone jack you mount under your rig's dash. This module eliminates the need for a laptop or any other outside device to set up the driveability of your engine.
Besides the calibration module, the Pro Flo system consists of the main manifold assembly containing the fuel injectors, fuel rails, air valve, idle air-control solenoid and a fuel pressure regulator. Also fitted into the manifold are the manifold absolute pressure sensor (MAPS), manifold air temperature sensor (MATS), coolant temperature sensor (CTS) and throttle position sensor (TPS). Many of these parts are standard OE pieces and can be bought at any parts store.
Edelbrock even provides the OE part numbers for you in the installation manual. All these components come pre-assembled to the manifold, something that greatly simplifies the overall installation process and leaves less room for error. You just need to install new gaskets and the whole assembly drops right in place of your old manifold and carb.
Also included is the electronic control module (ECM). The Edelbrock ECM is very similar in size and design to the ECMs used for years in GM TPI-equipped vehicles. It features a Motorola 68HC11 microprocessor and 32KROM--all well-proven stuff. A custom calibration chip, burnt by Edelbrock to your specific engine's cam specs, is included in the system's price, but you must send in a postage-paid card listing your cam's specs to receive your chip in the mail. It then takes only a few minutes to install it into your ECM.
Connecting all these goodies together is a very complete wiring harness. Although it takes some clever arranging to fit it all cleanly into a small rig, it really is a plug-and-play deal. All the connections are OE-style plugs that only fit their corresponding partners. There are only four outside connections to make to the vehicle's existing electrical system. These you can screw up, as I learned the hard way. Two wires go to 12V power, the other two go to a good ground. Making sure these connections are soldered and secure is essential for the system to run right. On three separate trail rides, I spent more time than I cared to spend tracing electrical wires with a test light.
Other bits and pieces found in the Edelbrock system include parts to convert your existing HEI distributor into a device containing a Hall-Effect switch. Once converted, the distributor's sole role is to tell the ECM the engine's crankshaft position. An "ignition amplifier," which appears to be basically a fancy red box to hold a new ignition module (since you were required to remove your old one from your distributor), must be mounted to the firewall. An O2 sensor is also included and must be mounted into your exhaust pipe somewhere near the exhaust manifold. Lastly, an externally mounted, high-pressure fuel pump, a fuel filter, lengths of high-pressure fuel line and return fuel-line hose, along with all the clamps, fittings and wiring to make it all work, are supplied.
The actual install was quite easy, since all the parts necessary are thoughtfully supplied in the kit and the installation manual is excellent. The only extra component I purchased for the conversion was a fuel cell with a small sump in its bottom to prevent fuel starvation to the external pump while poised at extreme angles.
The Bee has received a new body during the past year while I've been dialing the EFI in. This accounts for the variation of the vehicle in the photos, and also contributed somewhat to the length of time it has taken to dial everything in.
The learning curve has been long for other reasons besides a new body. Many thanks go out to my new friend Ray, age 20-something, who for a while became a permanent fixture in the right-hand seat, calibration module in hand. Ray dialed the system in while I drove. We floored the Jeep up windy mountain roads; hit 5,000 rpm bowling sand dunes, and crawled over large rocks at idle. It takes someone with knowledge of the workings of the components of EFI--and magic fingers--to make the Edelbrock system purr.
So how has the Killer Bee responded to the conversion? The ZZ4 feels like it has 100 more horsepower. It starts instantly and idles immediately, no matter how cold it is. It pulls strongly, with no flat spots, from idle to 5,500 rpm. It runs cooler, and always remains at a consistent temperature. It has instant throttle response. For crawling it was a bit too instant, and I've had to modify the geometry of the throttle linkage to mellow things out at tip-in. The exhaust even smells cleaner. All this, and it runs vertical and upside down--no problem. Now I just gotta learn my vertical limits.