Holley Conversion

Extra-Tech: Holley Conversion
Photos and Story by Daniel Maffett

If you’ve spent any time off-road with a carbureted vehicle, it probably didn’t take long to find the limits of a bowl of fuel sitting on top of the intake. Angles are not friendly to this dated, but effective, technology. You can solve this problem using an electronic fuel injection system that replaces your carburetor with a more efficient throttle body injection. The Sniper EFI, provided by our friends at Holley Performance Products, is a complete solution containing everything needed to complete the job.

The vehicle going under the knife today is my 1980 Jeep CJ7. The drivetrain is an AMC 258ci with a Weber 32/36 Carb, T176, Dana 300 JB conversion 4:1 kit. This powers the factory Dana 30 Spartan Locked front axle, and AMC 20 ARB Locked rear axle. Both have 4.56 gearing and alloy axle shafts from Ten Factory. The Jeep sits on about 4 inches of lift, between body and suspension, and 35 inch Milestar Tires.

Let’s get started. First up, out with the old; although this Weber carb has treated me well for many years and is far superior to the BBD Carter that the Jeep would have come with from the factory, I have reached its limits on the rocks. Removal is very straight forward. First, disconnect all fuel and vacuum lines. Follow this by disconnecting the linkage and filter assembly. Remove the four mounting bolts and the bolts holding the adapter to the manifold. What you’re left with is a bare BBD carb mounting flange in need of a quick cleanup. At this time, remove all metal and rubber lines from the old mechanical fuel pump. These will not be reused.

Just like that, the fun is ready to begin! The Holley Sniper kit provides four new mounting studs; these were installed with a dab of blue Loctite. The gasket was placed over the studs and the Sniper unit placed on top. In hindsight, trimming a bit of the length from the mounting studs would have made installation easier, as the studs’ installed height made finding the correct socket combo difficult.

Now it’s all about the connections. This is where the Holley Sniper kit is worth its weight in gold. Everything is bundled into very high-quality weather-tight wiring harnesses. They are well labeled and almost foolproof.  The coolant temp sensor was installed into an available ⅜” NPT port in the intake manifold and plugged into its appropriate harness. We then moved onto the air/fuel ratio sensor. The kit provides a nifty, no weld solution for drilling, and clamping into the exhaust. Given my factory manifold has a mounting bung for an O2 sensor, I choose to utilize that option. Next, we tackled the accessory harness. This is a 10-wire harness that handles the connections of your tech signal, fan controls, air conditioning signal, and a multitude of other tasks the unit can control. I de-pinned this connector of all the wires I will not be using. The remaining wires are output fan control one and coil wire. The output fan control was run to the relay previously installed to control my electric fans. THIS IS A GROUND CONTROL SWITCH, DO NOT ATTEMPT TO GROUND THE FANS DIRECTLY THROUGH THE UNIT. IT WILL FRY. Always use this lead to control a relay for this task. The coil wire went directly to the tach connection on my HEI distributor. It is important to note that this wire must be run away from any high voltage sources. Ignition coil, wires, cap, and spark plugs all cause interference that will wreak havoc on the system. The Holley Sniper system is capable of controlling ignition timing, however, I have decided, at least for the first go around, to leave this task to my HEI.

The final harness is the power. The main fuse holder and fuel pump relay were mounted to the firewall next to the battery. The Holley instructions make it very clear that the system positive and negative leads must be run directly to the battery. These systems are very sensitive to voltage variations; running straight to the battery ensures the cleanest possible power is received.  There is one more power connection required. This needs to be connected to a 12V source that is hot with both the Key on and while cranking. This was made easy for me as I already have this set up controlling my HEI distributor power relay. The factory wire that powers the ignition system is hot in both of these conditions, so you can steal power from here. The last connection I needed to run was the fuel pump power. This was loomed and ran along the frame rail to the Jeep’s rear where my fuel pump was mounted. With all of these connections, you want to use a secure connector and heat shrink to prevent corrosion and issues down the road.

Now onto the fuel pump. This kit is an add-on unit that is supplied with the Master Kit. The kit includes three key parts: a low-pressure pre-filter, a high-pressure post-filter, a high-pressure fuel pump, and all the connections and fuel hose to make it all come together. My install is slightly different from the average CJ7, as I’m running an RCI Fuel cell in the Jeep’s bed. Also, with my Jeep seeing the amount of rock bashing I’m accustomed to putting it through, I wanted to make sure it was in a safe place. I settled on the section of floor that steps up behind the driver’s seat under the Jeep. The fuel hose feeding the pump is run through a grommet and into the bed of the Jeep. It meets the low-pressure filter on this side and then into the pick-up feed of the fuel cell. Holley recommends ⅜” fuel line for this. The hard lines on my Jeep are 5/16″. I elected to run the installation this way, understanding that if I ran into a fuel delivery issue, I would know what needed to be done. As of today, I have nearly 500 miles of drive time, and I have seen no ill effects of this. Once again, make sure to use heat shrink on all connections.

Now to install the touch screen handheld. This unit’s harness is run through the firewall and plugs into the under hood harness. It’s then mounted with double-sided tape to the dash. (Image 6) Once mounted STOP! Go back and check all of your connections, fuel, and electrical. Once you’re positive everything is correct, it’s time to run the setup wizard. It’s an easy step-by-step process to follow along on-screen. Once set up, you will have all the gauges you could ever need at your fingertips.

I wish I had done this kit years ago. The drivability, tunability, and ease of install are next to none. After 500 miles, I continue to be impressed.