Spark Plug Wire Set Guide for the 1979 Chrysler 300
Keep the high-performance 360 V8 in your classic 300 firing on all cylinders with the right set of spark plug wires.
- This guide is specifically for the one-year-only 1979 Chrysler 300 with the 5.9L/360ci V8.
- Choose a direct-fit set for the Mopar 360 V8 to avoid length issues common with universal kits.
- Symptoms of failure include rough idle, misfires, and reduced power.
- Upgrading from a standard 7mm wire to a performance 8mm or 8.5mm wire is a cost-effective improvement.
About Your 1979 Chrysler 300
While the prompt mentioned 1978-1982, the special performance model known as the Chrysler 300 was produced for one year only in 1979. It was based on the Chrysler Cordoba platform but came standard with the potent E58 police-spec 5.9L (360ci) V8 engine. This makes your vehicle a rare, single-year model. Maintaining its unique ignition system is key to preserving its performance heritage.
Symptoms of Failing Spark Plug Wires
Worn-out spark plug wires can cause a range of problems. Because they fail gradually, you might not notice the slow loss of performance. Common signs include:
- Rough Idling: The engine may shake or vibrate more than usual when stopped.
- Engine Misfires: You may feel a stutter or hesitation from the engine, especially under acceleration. This can sometimes trigger a check engine light on later models, with codes like P0300 for random misfires.
- Reduced Power and Acceleration: The car may feel sluggish or slow to respond when you press the gas pedal.
- Difficulty Starting: A weak spark makes it harder for the engine to fire up, especially when cold.
- Decreased Fuel Economy: An inefficient spark means wasted fuel, leading to more trips to the gas station.
- Visible Damage: A visual inspection may reveal cracks, burns, or melting on the wire insulation or boots.
A Note on the Lean Burn System
Some 1979 models were equipped with Chrysler's electronic "Lean Burn" system, which can be a source of ignition problems. While the spark plug wires are a common failure point, if you continue to have issues after replacing them, the Lean Burn computer or its sensors could be at fault. Many owners in classic Mopar forums discuss bypassing this system.
Choosing the Right Aftermarket Spark Plug Wires
Original Equipment (OEM) wire sets for this vehicle are no longer produced by Chrysler. However, the aftermarket offers a wide range of excellent options. Fitment is important; some universal sets may have wires that are too long or too short for the 360 V8's layout, a common complaint among classic Mopar owners.
Brand Tiers
- Restoration-Correct: For owners seeking a factory-original look, brands like Lectric Limited or specialty Mopar parts suppliers like Herb's Parts offer date-coded wires that replicate the appearance of the originals. These are the most expensive but are essential for a concours-level restoration.
- Performance Aftermarket: Brands like MSD, Taylor Cable, and Accel are popular choices for improved performance. They often feature thicker 8mm or 8.5mm silicone jackets for better heat resistance and lower-resistance spiral cores for a hotter, more reliable spark. These are a great upgrade for any driver.
- Standard Replacement: Brands such as Standard Motor Products (SMP), NGK, and Denso offer quality, direct-fit replacement wire sets that meet or exceed original specifications. These are a reliable and affordable choice for daily drivers.
Pro Tip: Check the Diameter
When ordering, you'll see different wire diameters, like 7mm, 8mm, or 8.5mm. Stock wires were typically 7mm. Upgrading to a wider 8mm or 8.5mm wire provides better insulation and can help deliver a stronger spark, making it a worthwhile improvement for minimal extra cost.
Estimated Costs
| Part Type | Estimated Cost |
|---|---|
| Standard Aftermarket Set | $30 - $60 |
| Performance Aftermarket Set (MSD, Taylor) | $70 - $120 |
| Restoration-Correct Set | $100 - $200+ |
| Shop Labor for Installation | $75 - $150 |
Frequently Asked Questions (FAQ)
Do I need to replace the wires one by one?
Yes. To avoid mixing up the firing order, it is highly recommended to replace one wire at a time. Remove an old wire, match its length to a new one from the set, and install the new wire before moving to the next cylinder.
Should I use dielectric grease?
Yes, applying a small amount of dielectric grease to the inside of each boot is a good practice. It prevents the boots from sticking to the spark plugs and distributor cap, seals out moisture, and makes future removal easier.
Are more expensive wires always better?
Not necessarily. For a stock engine, a quality standard replacement set from a brand like NGK or SMP will perform perfectly well. Performance wires from MSD or Taylor offer better heat protection and may provide a slightly stronger spark, which is beneficial but not strictly necessary for a stock vehicle.
Can I use a universal wire set?
You can, but it's not recommended for beginners. Universal sets require you to cut the wires to the correct length and crimp the terminals yourself. A direct-fit set designed for the Mopar 360 V8 is much easier to install and avoids potential fitment problems.
Technical Specifications
Engine Application: 5.9L (360ci) V8 Distributor Type: Electronic Ignition (some with Lean Burn computer) Number of Wires: 9 (8 for spark plugs, 1 for coil)
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.