How-to: MSD Cut-to-fit Spark Plug Wires -
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post #1 of 1 Old 04-11-2012, 12:46 AM Thread Starter
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1990 YJ Wrangler 
Join Date: Jul 2011
Location: Neenah
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How-to: MSD Cut-to-fit Spark Plug Wires

After reading several of JeepHammers ignition upgrade articles, I decided to do a Team Rush upgrade to my Jeep. I followed his advice and used the MSD cut-to-fit spark plug wires. In my research, I found that several people had questions regarding the install. I installed my wires tonight and tried to document the process thoroughly. The instructions with the kit are complete, but slightly difficult to follow.

I used MSD part number 31179, a six wire universal plug wire kit.

This article will cover the method I used to size and install the wires on my 4.2L Inline 6. The following images are for the number 1 wire, but remaining wires are all processed the exact same way. The kit comes with two types of crimp terminals, I opted to use the dual-crimp style (shorter crimp terminal) since they appeared as if they would fit into the boots easier.

1. Connect and lay out all of the wires in the engine compartment. To size the wire, hold it in its intended path and mark the wire where it will pass into the boot as shown below, near my index and thumb.

2. Remove the wire and take it back to your work bench. Make a 2nd mark 1" down from the original (longer wire). This will become your final wire insulation length. NOTE: For the coil wire, you will make this mark 1-1/4" from your first mark. The coil wire boot is longer than the standard boots.

3. Slide the wire into the supplied tool and line your second mark up as shown. Add a 3rd mark at the small ridge. This mark will represent your final wire length.

4. Cut the wire off at the 3rd mark.

5. Place the wire back in the tool and line up the freshly cut end with the small ridge (where you previously placed your third mark). Using a razor or utility knife blade, cut through the insulation using the supplied tool as a guide. Hold the blade in position and carefully rotate the wire. Remove the wire and then finish the cut by carefully slicing the remaining white kevlar fibers. Twist the cut insulation off counterclockwise. You should end up with the core wire exposed as shown.

6. Next, take one of your crimp terminals and bend the tabs in as shown with needle-nose pliers. Tab size should be 1/16" to 1/8".

7. Slip the crimp terminal onto the wire with about 1/16" to 1/8" of insulation extended beyond the crimp lugs. This is a good time to go back to your Jeep and check that the crimp terminal is oriented correctly. This is more important for short wires. Otherwise you might have to twist your wire to install it.

8. Next, install the terminal into the "W" block as shown. To do this you will probably need to pre-crimp the terminal with some pliers, otherwise it won't fit into the block.

9. Install the back half of the supplier crimp block.

10. Next, crimp the terminal. The directions recommended the use of a bench vise. I didn't have one, so a C-clamp was used. I think a bench vice would probably work a little better. Don't over crimp at this stage. You can do this in several stages. You want to firmly depress the lugs into the insulation, but not to the point of cutting it.

11. Completed first crimp!

12. Next use needle-nose pliers to crimp the small core wire lugs. Here you only want to snug it down. Try to do this as evenly as possible since you don't want to actually cut the small spiral core wire.

13. Apply some dielectric grease to the terminal, align the "cup" portion of the terminal with the boot opening, and then slip the boot on. Try to support the wire as much as possible during this process. You don't want to fold the wire too sharply. There will be some significant resistance but it will eventually go. Originally I thought that you would preinstall the boot, but don't! You should never pull on the wires as this might separate all of the work you just did. And now you have one finished wire. Only 6 more to go (don't forget the coil!)

14. Here is my finished setup.

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