Choosing the Right Spark Plugs for Your 1984-1986 Dodge Conquest
Get the correct spark plugs for your Conquest's 2.6L turbo engine to restore power and prevent misfires.
- NGK is the most recommended brand for the Conquest's 2.6L turbo engine; the BPR6ES is a popular choice.
- Checking and setting the spark plug gap is critical; start at 0.044" for a stock engine and reduce if you have misfires.
- Due to the turbocharged engine, using a quality plug is more important than on a non-turbo car.
- This is an easy and inexpensive DIY maintenance item that can significantly improve engine performance.
Signs of Failing Spark Plugs in a Conquest
Worn-out spark plugs can cause several noticeable problems in your 1984-1986 Dodge Conquest. Because the ignition system is less powerful than modern designs, it is sensitive to plug wear. You might notice a rough idle, where the engine shakes or vibrates more than usual. During acceleration, the car may hesitate or feel sluggish. A common and serious symptom is engine misfiring, especially under boost, which can feel like a sudden stumble or loss of power. Reduced fuel economy is another sign that your plugs are no longer firing efficiently.
Choosing the Right Aftermarket Spark Plug
For a classic turbocharged vehicle like the Dodge Conquest (and its twin, the Mitsubishi Starion), the quality of your spark plug matters. While many brands are available, owner experiences consistently point to Japanese brands as the top choice for reliability and performance in the G54B engine. Original equipment plugs were likely made by NGK, so choosing a high-quality aftermarket equivalent is a safe bet.
Brand Quality Tiers
- Best (Highly Recommended): NGK and Denso are the preferred brands for the Conquest. NGK is the most frequently recommended brand in owner forums, with specific part numbers like BPR6ES often cited for stock or lightly modified engines. These brands are known for their quality construction and reliability in Japanese engines.
- Good (Reliable Alternatives): Bosch and Autolite offer quality spark plugs that will work well in the Conquest. Bosch offers modern plug designs like iridium and platinum that can provide a long service life. Autolite is a well-regarded American brand with a solid reputation.
- Standard (Budget-Friendly): Champion is another available brand. While they can perform adequately, most owners of these specific vehicles prefer to use NGK or Denso for best results with the turbocharged engine.
Aftermarket Spark Plug Cost
| Tier | Brand Examples | Price Range (per plug) |
|---|---|---|
| Best | NGK, Denso | $4.00 - $16.38 |
| Good | Bosch, Autolite | $3.50 - $12.00 |
| Standard | Champion | $2.84 - $8.00 |
Check the Gap!
The single most important step when installing new spark plugs is to check the gap. The recommended gap for a stock Conquest is typically 0.044 inches. However, if your engine is modified for higher boost, you will likely need a smaller gap to prevent the spark from being "blown out" under pressure, which causes misfires. Always use a gapping tool to verify the measurement before installation.
Frequently Asked Questions (FAQ)
What is the best spark plug for my Conquest?
Based on extensive owner feedback, NGK spark plugs are the top recommendation. The NGK V-Power BPR6ES is a very common choice for stock engines. If your engine is modified to produce more power and heat, a "colder" plug like the BPR7ES may be necessary to prevent detonation.
What spark plug gap should I use?
For a stock 1984-1986 Conquest, the standard gap is 0.044 inches (1.1mm). Some NGK plugs have this preset, designated by a "-11" at the end of the part number. If you experience a misfire under acceleration, especially with increased boost, you should reduce the gap in small increments (e.g., to 0.040" or 0.035") until the misfire is gone.
Should I use copper, platinum, or iridium plugs?
For the 1980s ignition system in the Conquest, standard copper plugs (like the NGK BPR6ES) work exceptionally well and are cost-effective. Platinum and iridium plugs offer a much longer service life but may not provide a noticeable performance benefit on this specific engine unless the rest of the ignition system is upgraded. Given the low cost, many owners prefer to stick with copper plugs and change them more frequently.
Are there any recalls or TSBs for Conquest spark plugs?
No, there are no known recalls or Technical Service Bulletins (TSBs) from Dodge or Mitsubishi related to spark plugs for the 1984-1986 Conquest. Any issues you encounter will likely be due to normal wear, incorrect plug choice, or improper gapping.
Technical Specifications
Thread Size: 14mm Hex Size: 13/16" (20.6mm) Seat Type: Gasket Standard Gap: 0.044" (1.1mm)
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Dodge Conquest: