Spark Plugs for the 1979 Chrysler 300: A Complete Guide
Keep your classic 360 V8 running strong with the right set of spark plugs.
- This guide is for the 1979 Chrysler 300, which came with a 5.9L (360) V8 engine.
- Stick with standard copper spark plugs from brands like Champion or NGK; expensive platinum/iridium plugs are not necessary.
- Always set the spark plug gap to 0.035 inches before installation.
- If engine problems persist after replacement, investigate the vehicle's original 'Lean Burn' ignition system, which is a known failure point.
A Note on Vehicle Years
When shopping for parts, you may see this vehicle listed in a 1978-1982 range. However, this specific generation of the Chrysler 300, built on the R-body platform, was only produced for the 1979 model year. All information here is specific to the 1979 Chrysler 300 and its standard 5.9L (360 c.i.d.) V8 engine.
Symptoms of Failing Spark Plugs
Worn-out spark plugs can cause a number of noticeable issues. If you experience any of the following, your plugs might be the culprit:
- Rough Idle: The engine may shake or vibrate more than usual when stopped.
- Engine Misfires: You might feel a hesitation or stumble from the engine, especially under acceleration.
- Poor Fuel Economy: If you're filling up the gas tank more often, failing plugs could be wasting fuel.
- Hard Starting: The engine may take longer to crank and start, or it might not start at all.
- Reduced Power: The car may feel sluggish and slow to accelerate.
A Note on Chrysler's "Lean Burn" System
These cars came from the factory with an early electronic ignition system called "Lean Burn". This system was known to be unreliable and can cause issues like engine pinging, hesitation, and poor performance that mimic bad spark plugs. Many owners have since replaced the Lean Burn computer and distributor with a more reliable standard electronic ignition system. If you have persistent running problems after changing your plugs, the Lean Burn system could be the real issue.
Choosing the Right Aftermarket Spark Plugs
For your 1979 Chrysler 300, the original technology was a standard copper core spark plug. You do not need expensive, modern plugs to get great performance.
OEM vs. Aftermarket Quality: For this vehicle, there is no significant quality difference between an OEM "Mopar" plug and a quality aftermarket plug from a trusted brand. The original plugs were often made by companies like Champion, so buying a Champion plug is essentially buying the original part without the Mopar box.
Recommended Spark Plug Tiers
- Tier 1: Standard Copper (Recommended): These plugs are the best match for your engine's original design. They provide excellent performance and are very affordable. Brands like NGK (V-Power), Champion (Copper Plus), and Autolite are all excellent choices. They work perfectly with the stock ignition system or common aftermarket upgrades.
- Tier 2: Platinum or Iridium: While available, these long-life plugs are not necessary for your classic V8. They cost significantly more and offer no real performance benefit for this engine technology. Stick with standard copper plugs and change them at the recommended interval.
Check the Gap!
Always check the spark plug gap before installation, even if the box says they are "pre-gapped". The correct gap for the 5.9L V8 engine is 0.035 inches. An incorrect gap can cause misfires and poor performance. Use a spark plug gapping tool to ensure each plug is set correctly.
Estimated Replacement Costs
| Part/Service | Estimated Cost |
|---|---|
| Aftermarket Spark Plugs (Set of 8) | $25 - $50 |
| Shop Labor | $100 - $200 |
| Total Professional Replacement | $125 - $250 |
Note: The labor costs found in many online estimators are for modern V6 engines that require removing the intake manifold and do not apply to your vehicle. The cost for your 1979 V8 will be much lower due to easy access.
Frequently Asked Questions (FAQ)
How often should I change the spark plugs on my 1979 Chrysler 300?
For standard copper spark plugs, a good rule of thumb is to replace them every 20,000 to 30,000 miles or every 2-3 years to keep the engine in top condition.
Is replacing the spark plugs a good DIY job?
Yes, this is a great DIY job for beginners. The spark plugs on the 360 V8 are easy to access. You will need a ratchet, a spark plug socket, an extension, and a gapping tool. The difficulty is very low.
Do I need to replace the spark plug wires at the same time?
It is a good practice to replace the spark plug wires when you replace the plugs, especially if they are old. Old wires can crack and leak voltage, preventing the spark plug from getting the energy it needs. Inspect them for any cracks, brittleness, or damage.
Are there any recalls for the spark plugs on this car?
No. A search of the National Highway Traffic Safety Administration (NHTSA) database shows no recalls related to spark plugs for the 1979 Chrysler 300.
Technical Specifications
OEM Part Numbers: RN14YC
Engine: 5.9L (360 c.i.d.) V8 Number of Plugs: 8 Plug Type: Standard Copper Core Spark Plug Gap: 0.035 inches
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.