How to Crimp Spark Plug Wires? (4 Quick Steps)

Knowing how to crimp spark plug wiresis essential, especially if it is a DIY spark plug wiresinstallation. The problem with crimping plug wires is that incorrectly doing the process can harm your ignition system.

In this article, we will look at how to crimp spark plug wires and the tool required for the process. We will also answer other related questions.

crimping spark plug wires

Tools Required For Crimping Spark Plug Wires

When it comes to crimping spark plug wires, it has to be done correctly. A simple error can create a gap between the spark plug wire ends and the terminal and could be harmful. It increases the resistance and places strain on the ignition system and may result in vibration after changing spark plugs.

The way to ensure that the crimping process is done correctly is to use the right tools.

Below are the tools you will need for crimping your spark plug wire.

1. Pro spark plug wire crimper tool (specific to crimping)

2. Ratcheting crimpers

3. Terminal ends

4. Plug boots for socket distributors

5. Stand-alone wire strippers

A Functioning spark plug starts with a crimp which can be found between the wire terminal and the spark plug wire. One of the critical processes in a spark plug wire installation is crimping properly by crimping the wires. Getting these tools gets you to the right start.  

How to Crimp Spark Plug Wires (Proper Steps)

Now that you have the proper tools, you need a guide to crimp your spark plug wires. If this is your first time learning how to crimp a spark plug wire, you do not have to rush; spend time to understand each type and ensure you do it properly.
Spark Plug Wire Crimping YouTube

Below is an easy-to-understand step-by-step guide to crimping your spark plug wires.

1. Strip wire

When crimping a spark plug wire, the first thing is to strip the silicone layer. You may use a striper to make it much more manageable.

Strip the outer silicone layer and leave about 0.75-1 inches of the conductor out, which will be used for a single-crimp terminal. If you have a dual crimp done, you will need a shorter length.

2. Find out the terminal type

The terminal type will determine the modification you must do to the crimping method. A majority of spark plug terminals come with just one crimp. Double-crimp terminals are primarily found in HEI-style terminals and are not common.

Note: For Single-crimp:

3. Fold the conductor wire

If you are dealing with a single crimp, fold the conductor over the silicone jacket. While doing this simultaneously, hold the conductor and make sure it is in place. Then slip the terminal over the conductor wire and push the wire inside the terminal saddle.

4. Crimp the wire

Get your pro crimp tool and adequately fit the spark plug wires and the terminal into the tool. Squeeze firmly on the tool until you are sure that the abs are folded and appropriately crimped. Check the connection to ensure that it is done correctly.

Slide the process for each spark plug in the boot cover over each terminal end.

Note: For Double-Crimp Wire Terminals:

For double crimp wire terminals, you have to for the above process up to step 2. Once you are moving to step 3, consider the following steps.

You must separate the conductor and jacket in a double crimp wire. As we said in step two, the conductor is crimped in a smaller area to do this. The silicone jacket will be crimped below the larger area.

Try to crimp the silicone jacket before moving on to the conductor.  

What Does Poor Crimping Cause?

Poor crimping is a major cause of electrical problems with spark plug wires. When the crimping process is done poorly, the wire is exposed to all sorts of external contamination, which could cause corrosion, poor wiring performances, white tip spark plug and even electrical failure.

What crimping does is it provides a form of compressing a terminal to a wire conductor without soldering. A gap occurs when crimping is not done well during a spark plug wire boot installation or other wiring fixes.

A strain is placed on the ignition system when there is a gap between the terminal and wire conduction. As electricity travels to the ignition system wiring to the spark plug, the gap map allows for a proper spark to be made by the spark plug. In this case, you might have to try repeatedly until you get a proper ignition.

If your spark plug wire assembly has poor crimping, and you continue to use it like that, you might end up with severe damage, and replacing the spark plug bootmight be the next option. 

Can Spark Plug Wires Be Shortened?

Yes, spark plug wires can always be cut and crimped to your desired length. Finding a spark plug wire that perfectly fits your car might be tricky. Instead Of looking for the perfect wire, you can always cut the one you have to the size you want. However, it has to be done right.

To understand how to shorten spark plug wires, you need to get the right to do it right to have it done right. To complete this process, you need the tools mentioned in the steps to crimp your spark plug wire, and a cutting tool like a knife.

You must measure the wire to know how much you need for your vehicle. You can do this by comparing the wiring to your old one. Cut the wire as you have measured it.

Once you can perfectly cut the wire, you will need to crimp it. You can follow the previous steps to do this, and you are good to go.


Installing spark plug wires, finding the correct wire for your vehicle, properly crimping it, and connecting them properly. In some cases, you may need to cut the wire before crimping it, that is, if your wire is too long. You need to ensure that all these processes are done right. If you do not have any prior knowledge, there is no harm in seeking help from a professional. 

Akindayini Temiloluwa

I am Akindayini Temiloluwa, an automotive expert writer and car enthusiast. I have over three years of experience in the automotive writing niche and have completed over 300 pieces of content from 50 projects. I have vast knowledge and skill in vehicle repairing, all mechanical work, car upgrades and maintenance. My goal as an automotive content writer is to simplify the most challenging concepts for my readers, help them self-diagnose what may be wrong with their vehicles and offer real value for their time.

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