International Full Size Jeep Association
Home Forums Reader's Rigs Tech Library

Hosting Services Provided by BJ's Full-Size Jeep Parts

Jacob's Ultra Pak Installation

Contributed By: Jack McAdams

The physical installation of the Jacob's Ultra Pak Ignition system in a 1991 Jeep Grand Wagoneer (AMC 360 CI) was fairly straightforward. The directions provided with the Ultra Pak were quite good and provided sufficient detail to make the task as simple as could be expected.

What follow is a review of the procedures followed during the installation, problems encountered, and a very early comment on the performance of the Ultra Pak system. This document will, hopefully, make it a bit easier for anyone desiring to follow in my footsteps!

Installation Procedure


Read carefully all of the documentation provided with the Ultra Pak.. Several reviews will provide a pretty good idea of what you are going to do before even opening the hood.

Locating a suitable mounting location

I chose to relocate as little existing hardware under the hood as possible. It was also decided to leave all existing ignition system components in place. This provides an immediately available backup in the event of a failure of one of the Ultra Pak components. These desires and a jap-packed-full engine compartment severely limited the mounting options. It appears that the inner fender wells would provide a suitable mounting location, but there is little free space available. The space which seemed to work best was on the fan shroud.

Installing the Energy Pak and Coil

NOTE: A more proficient mechanic could probably find a lot easier way to do this. This, however, was the process I followed.

1. Remove all wire ties from the Energy Pak and Coil assemblies.

2. Remove the radiator and fan shroud mounting bolts (4).

3. Remove upper radiator hose from the radiator. Catch coolant in a suitable container.

4. Carefully remove the fan shroud by lifting straight up.

5. The Energy Pak is installed on the driver's side of the shroud, the coil on the passenger side.

6. I used a Dremel tool to cut away a portion of a shroud reinforcing rib so that the Energy Pak would lie flat on the shroud. This step is not required, but makes a neater installation.

7. Hold the Energy Pak in place and drill four holes for the screws through the shroud. The Energy Pak should be oriented so that the wires from it are facing up, toward the hood.

8. Note the location of the radiator mount lower bolt hole closest to the fender. Mark this position on the base / heat sink of the Energy Pak. Use a Dremel tool or hacksaw to remove the interfering portion of the base / heat sink. You could probably skip this step, but I preferred to have all four bolts securing the radiator.

9. Tape the ends of the orange and purple wires as they are not used. I used a wire nut.

10. Install the Energy Pak on the shroud using 1/4" screws, lock washers and nuts. I chose to use double nuts to ensure a secure mount. Ensure that the Energy Pak does not encroach on the radiator mounting bolt holes. Note that the screw heads are on the grille side of the shroud, the nuts are on the engine side.

11. Hold the coil in place on the passenger side of the shroud. Drill four holes for the screws through the shroud. The coil should be oriented so that the wires from it are facing toward the battery tray. The coil is mounted so that it will be just below the battery mounting tray. It must be positioned as far outboard on the shroud as possible to avoid interference with the alternator pulley and belts.

12. Install the coil on the shroud using 1/4" screws, lock washers, and nuts as in step 10 above.

13. Carefully reinstall the fan shroud. It may be necessary to replace the radiator mounting bolt on the lower Energy Pak, fender side, with one 1/2" longer than original.

14. Replace the upper radiator hose and replace any lost coolant.


1. Lay the wiring from the coil and Energy Pak in their approximate final location. Ensure there is sufficient length and that the wires do not interfere with any moving parts nor come in contact with hot components. I chose the following wire paths:

2. From the coil - under the air filter input hose, around the bottom on the battery tray, behind the charcoal canister to the OEM coil.

3. From the Energy Pak - along the inside fender well to a point just in front of the brake fluid reservoir, past the front of the air cleaner housing to the starting relay on the passenger fender well. The connectors which join the Energy Pak and the Coil will meet just in front of the air cleaner. The fuse holder will also be located here, making ti readily available. NOTE: Steps 2 & 3 above are easier if you disconnect the two connectors joining the Energy Pak to the Coil.

4. The +12 volt wire (heavy red) from the Energy Pak was connected to the starting relay +12 volt bolt. This is a direct connect to the battery via a heavy cable (see comments below).

5. The ground wire (heavy black) from the Energy Pak was connected to frame ground by means of a 1/4" self-tapping screw in the fender well immediately adjacent to the starting relay. (See comments below).

6. The coil to distributor high-voltage lead was run in front of the charcoal canister and directly to the distributor.

7. The coil ground wire (thin black) was connected to frame ground using one of the existing screws which hold the air filter hose in place.

8. Remove the original equipment "horseshoe" connector from the old coil.

9. Connect the red and green wires from the Energy Pak connectors to the horseshoe connector (green to tach) using the spade connectors provided. (See Comments below)

10. Reconnect the two connectors between the Energy Pak and the coil (if disconnected).

11. Secure all wiring in place with tie wraps. The more the merrier!

12. I placed the horseshoe connector (with the Jacobs wires) back on top of the original equipment coil and held it in place with a tie wrap. The original coil wire was left connected to the coil and tie wrapped out of the way.

13. Ground or install the anti-theft wire. Mine is currently grounded to the frame, the anti-theft feature to be installed some time in the future.

Final Inspection

1. Check, recheck, then check again that all wires are going to the proper place and are not in a position to come in contact with any moving or hot parts.

2. Install the provided 15 amp fuse in the fuse holder. Install fuse holder cap.

3. Recheck clearances between the coil, Energy Pak, and all moving parts.


Start the engine! If it fails to start you may have forgotten the fuse (I did!).


1. The installation of space lugs into the receptacles on the horseshoe connector seems a bit kludgey. I would prefer to see a direct hard connection to the pickup wires. I'm going to explore this further.

2. The physical mounting scheme I used prevented what I would consider "proper" routing of the wires from the Energy Pak. I would have preferred to run all of the wires from the Energy Pak, along the fender well, along the fire wall, and down the opposite fender well. I would estimate that this would require an additional six to eight feet of cabling. I could have cut and spliced in additional wire and will probably do so later.

3. The +12 volt and ground wires were connected to the starter relay instead of directly to the battery only because of the wire-length problem. Jacob's directions are to connect direct to the battery posts.

4. One frightening problem was noted: The engine will not turn off with the ignition key! I spoke to Tech Support at Jacobs and they claim that there is a problem with the AMC 360 electrical system in that leaking or residual voltage is present with the key off, or something like that. I don't really understand it but they are going to ship me some sort of adapter that goes on the back of the alternator. In the interim I installed a relay between the +12 volts at the starter switch and the Energy Pak. It is triggered from the switched lead coming from the ignition switch to the starter switch. Seems to work OK.

5. Installation time to this point was 4.5 hours. I still need to install the new plug wires, gap the plugs, install the anti-theft switch, and resolve the "turn=-off" problem.


1. The Grand Wagoneer started at the turn of the key - no stalling, immediate start! This is a first since I've owned it!

2. Idle is super smooth. There is no longer any missing whatsoever.

3. Acceleration while running seems to be improved quite a bit (Ed. note: how's the acceleration when not running? (grin)). This is subjective as I have no means of measuring it.

4. Acceleration from a stop is much improved. Previously noted hesitation is gone!

5. It is much too early to report on the impact on mileage. I look forward to providing an update in a couple of weeks.

Jack McAdams

corner corner