How to choose ignition wires
Compare EPDM and silicone jackets, choose a cable diameter and confirm the complete set against your vehicle.
Start with the vehicle, then select the construction
Send the OE reference, vehicle model, year and engine. Confirm cable lengths, terminal shape and boot angle before choosing the jacket material and diameter. A matching number is a starting point; the complete assembly must fit.
We accept inquiries for EPDM and silicone jackets in 5, 7, 8 and 10 mm outside diameters. Availability of each combination is confirmed for your selected reference.
EPDM vs silicone: what is the difference?
| Selection point | EPDM | Silicone |
|---|---|---|
| Material | Ethylene propylene diene rubber | Silicone rubber |
| Our available temperature specification | −40°C to +120°C | Up to +150°C |
| Selection focus | Match this range to the intended operating environment. | Consider when the application requires a higher upper temperature limit. |
| What to confirm | Continuous and peak temperature ratings, insulation construction, boot material and operating conditions. | |
These are the temperature specifications for our offered material options. Confirm the applicable cable construction, exposure duration and complete assembly specification for your order. The silicone lower temperature limit is confirmed by model. Jacket, inner insulation and boots may use different materials.
Technical background: NGK wire-set construction guide.
5 mm, 7 mm, 8 mm or 10 mm?
These sizes describe the cable's outside diameter, not the conductor size. A thicker cable is not, by itself, proof of a stronger spark or better engine performance.
| Requested size | Fit checks before ordering |
|---|---|
| 5 mm | Confirm that the original application specifies this size and that the boots and terminals match. |
| 7 mm | Check the original cable diameter, clips and complete set specification. |
| 8 mm | Check fit in cable separators, boot entries and routing spaces. |
| 10 mm | Check larger-diameter clearance, separators, bend routing and boot compatibility; do not assume it is a direct upgrade. |
Also confirm conductor construction and interference suppression with the ignition-system requirements. Diameter alone cannot tell you resistance or compatibility.
Construction example: MSD lists outside diameter, core and resistance separately. This is an external technical example, not a VEXIRA specification.
Conductor, suppression and insulation
Compare conductor construction, specified resistance and interference suppression as well as the jacket. A low resistance figure or a larger outside diameter alone does not establish suitability for the ignition system. Ask for the specification of the selected set.
Further reading: Magnecor technical questions on cable diameter and conductors.
Installation and use
- Follow the vehicle service procedure. Switch off the ignition and let the engine cool before work; do not handle ignition leads with the engine running.
- Replace one lead at a time to preserve the correct connection order.
- Follow the original routing and reuse suitable clips. Keep leads clear of hot surfaces, sharp edges and moving parts.
- Seat boots and terminals fully. When removing a lead, grip the boot rather than pulling the cable.
- Check damaged insulation and loose connections. Use the specified resistance test and limits for the selected cable, rather than one universal limit.
Installation reference: NGK wire-set installation instructions.
Common buying questions
What temperature options do you offer?
Our EPDM option covers −40°C to +120°C; our silicone option is available up to +150°C. Confirm the model and exposure conditions when requesting a quote.
Is silicone always better than EPDM?
Choose the compound and complete cable specification that meet the application's heat and insulation requirements. The material label alone is not enough.
Can I replace a 7 mm cable with a 10 mm cable?
Only after confirming the assembly, boots, terminals, routing and ignition-system requirements. Do not choose by diameter alone.
What if my OE number is not listed?
Send it with your vehicle model, year and engine. We will check the reference and available construction options before quotation.
Choose options & request a quote