A Guide to Choosing Spark Plugs for the 1978-1985 Dodge Magnum
Keep your classic Mopar V8 firing on all cylinders with the correct set of new aftermarket spark plugs.
- Your 1978-1985 Magnum requires eight spark plugs, and you must choose a set that is compatible with your specific V8 engine (e.g., 5.2L/318, 5.9L/360).
- Standard copper plugs from Champion or Autolite are a cost-effective choice that works well but requires more frequent replacement.
- Upgrading to platinum or iridium plugs from brands like NGK or Denso provides a longer lifespan and more consistent performance.
- Always check and set the spark plug gap to your vehicle's specification (typically 0.035") before installation.
Signs of Failing Spark Plugs
Worn-out spark plugs can cause several noticeable problems. If your Magnum is experiencing a rough idle, hesitates when you accelerate, or you notice a drop in fuel mileage, it might be time for a new set of plugs. A check engine light for a misfire (codes P0300-P0308) is a definite sign, though these lights are less common on older models. You might feel the engine stutter or shake, especially under load.
Choosing the Right Aftermarket Spark Plug
For a vehicle like the 1978-1985 Dodge Magnum, aftermarket spark plugs from reputable brands often meet or exceed the quality of the original parts from the 1970s. The key is to choose the right material and brand for your needs. Your Magnum has a V8 engine, so you will need a set of eight plugs.
Brand & Material Tiers
Good: Standard Copper Plugs
Brands like Champion and Autolite offer traditional copper spark plugs. Champion was often the original equipment for Chrysler vehicles, so they are a tried-and-true choice. Copper plugs provide excellent performance and are very budget-friendly. Their main drawback is a shorter lifespan; they should typically be replaced every 15,000 to 20,000 miles. For a stock engine and owners who don't mind regular maintenance, copper plugs are a great value.
Better: Platinum Plugs
Brands like NGK and Denso offer single or double platinum plugs. These are a good upgrade from copper, featuring a platinum disc on the electrode that resists wear. This allows them to last much longer, often up to 60,000 miles. They provide a consistent spark over their lifespan and are a great “set it and forget it” option for daily drivers.
Best: Iridium Plugs
For the best performance and longest life, look to iridium plugs from brands like NGK, Denso, and Accel. Iridium is an extremely hard material that allows for a very fine center electrode, which creates a more focused and powerful spark. This can lead to improved throttle response and maximum engine efficiency. They have the longest service interval, often exceeding 80,000 miles, making them ideal for performance-modified engines or for owners who want the absolute best available.
Aftermarket Spark Plug Cost
| Tier | Typical Price (per plug) | Typical Price (set of 8) |
|---|---|---|
| Standard Copper (Autolite, Champion) | $3.50 - $5.00 | $28 - $40 |
| Platinum (NGK, Denso) | $5.00 - $10.00 | $40 - $80 |
| Iridium (NGK, Denso, Accel) | $9.00 - $15.00 | $72 - $120+ |
A Note on Brands
While Champion was the original supplier for many Mopars, many enthusiasts in online forums prefer NGK plugs, citing better reliability and resistance to fouling. Autolite is also a popular and affordable choice. Ultimately, any of the listed brands will perform well if you choose the correct plug for your engine.
Known Issues, Recalls, or TSBs
For the 1978-1985 Dodge Magnum, there are no active recalls or Technical Service Bulletins (TSBs) specifically related to spark plugs. Any issues you encounter will likely be due to normal wear and tear from age and mileage, not a manufacturing defect.
🎬 Watch this video to learn more about common Magnum issues.Frequently Asked Questions (FAQ)
What is the correct spark plug gap for my Dodge Magnum?
The most common spark plug gap for the V8 engines in this era (318, 360, 400) is 0.035 inches. However, you should always verify this by checking the emissions sticker under the hood of your vehicle or consulting a factory service manual. Always use a gap tool to check and adjust the gap on each new plug before installation.
How often should I change my spark plugs?
This depends on the type of plug you use. Standard copper plugs should be changed every 15,000-20,000 miles. Platinum and iridium plugs can last much longer, typically between 50,000 and 80,000 miles or more.
Do I need special tools to change the spark plugs?
No, this is a very DIY-friendly job. You will need a basic socket set with a ratchet, an extension, a dedicated spark plug socket (usually 13/16" for these vehicles), and a spark plug gap tool. The spark plugs are easily accessible on top of the engine.
Should I use anti-seize on the spark plug threads?
Yes, it is a good practice on these older engines with iron heads. Apply a very small amount of anti-seize compound to the threads of the new plugs, being careful not to get any on the electrode or porcelain insulator. This will help prevent the plugs from getting stuck, making future changes easier.
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Technical Specifications
OEM Part Numbers: RJ12YC XR5
Number of Cylinders: 8. Common Engines: 5.2L (318ci), 5.9L (360ci), 6.6L (400ci) V8. Spark Plug Socket Size: 13/16 inch. Standard Spark Plug Gap: 0.035 inches (always verify).
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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.