Choosing the Right Spark Plugs for Your 1971-1977 Dodge Colt
Keep your classic Colt running smoothly with the correct new spark plugs for its Mitsubishi-designed engine.
- For the Mitsubishi-built engine in your Colt, NGK or Denso brand spark plugs are highly recommended.
- Standard copper plugs are the best and most cost-effective choice; expensive platinum or iridium plugs are not necessary.
- Always check and set the spark plug gap to approximately 0.028-0.032 inches before installation.
- Replacing spark plugs is a simple, beginner-friendly maintenance task on this vehicle.
Signs of Failing Spark Plugs in Your Colt
An old car like the 1971-1977 Dodge Colt gives clear signs when its spark plugs are wearing out. Because these engines are simpler than modern ones, you might notice problems more quickly. Look for these common symptoms:
- Hard Starting: If your Colt takes longer to start or you have to crank the engine a lot, weak spark plugs could be the cause.
- Rough Idle: A vibrating or shaky feeling when the car is stopped but the engine is running often points to a spark plug not firing correctly.
- Poor Fuel Economy: Worn plugs can't burn the fuel mixture efficiently, which means you'll be stopping for gas more often.
- Engine Misfires: You might hear a sputtering or stumbling sound from the engine, especially when you accelerate. This happens when a plug fails to spark, leaving fuel unburnt.
- Sluggish Acceleration: If your Colt feels slow or hesitant when you press the gas pedal, it may not be getting the strong, consistent spark it needs.
Reading the Old Plugs
When you remove the old spark plugs, look at their tips. A healthy plug will look light brown or grey. If a plug is black and sooty, your engine might be running rich (too much fuel). If it's covered in oil, it could be a sign of engine wear, which is common in older vehicles.
Choosing the Right Aftermarket Spark Plugs
The 1971-1977 Dodge Colt was built by Mitsubishi, so its engine has Japanese roots. This is important when choosing spark plugs. While original OEM plugs may be hard to find, today's aftermarket brands offer excellent quality.
Brand Tiers for Your Dodge Colt
For a vintage, carbureted engine like the one in your Colt, you don't need expensive, fancy plugs. A reliable, standard copper plug is often the best choice.
- Tier 1 (Best Match): NGK & Denso
These Japanese brands are often the original equipment for Mitsubishi engines. Many mechanics and classic car owners trust NGK and Denso for their reliability and consistent performance, especially in Japanese vehicles. They are an excellent choice for a stock 1971-1977 Colt. - Tier 2 (Good Alternatives): Autolite & Champion
Champion was a very common American brand during the 1970s and may have even been installed by dealers. Autolite is another well-known aftermarket brand that has made plugs for decades. Both offer standard copper plugs that are affordable and work well in these simple engines. - Tier 3 (Consider if Available): Bosch
Bosch is a huge parts manufacturer, but some mechanics report mixed results when using their plugs in vintage Japanese engines that didn't come with them originally. They are a fine choice if other brands are not available, but NGK or Denso are generally preferred for your Colt.
What About Platinum or Iridium Plugs?
Modern platinum and iridium plugs are designed for high-energy ignition systems and long life (60,000+ miles) in newer cars. Your Colt's 1970s ignition system doesn't require these advanced plugs, and you won't see a performance benefit. Stick with the more affordable and appropriate standard copper plugs, which should be checked or changed more frequently.
| Part Type | Price Range (Per Plug) |
|---|---|
| New Aftermarket (Copper) | $3.23 - $7.00 |
| New Aftermarket (Platinum/Iridium) | $8.00 - $16.38 |
Frequently Asked Questions
Do I need to gap the new spark plugs?
Yes. Even if plugs say they are "pre-gapped," you should always double-check the gap with a feeler gauge or gapping tool before installation. The correct gap for the 1.6L and 2.0L engines in these Colts is typically between 0.028 and 0.032 inches. An incorrect gap can cause misfires and poor performance.
How often should I change the spark plugs on my Colt?
For a classic car with standard copper spark plugs, it's good practice to inspect them every 10,000-15,000 miles and replace them every 25,000-30,000 miles, or sooner if you notice any performance issues. Given the age of the vehicle, regular checks can also help you spot other engine problems.
Is replacing the spark plugs a difficult job?
No, this is a very easy job on a 1971-1977 Dodge Colt. The spark plugs are located on the top or side of the engine and are easy to access. You will need a ratchet, an extension, and a spark plug socket. Make sure to replace them one at a time to avoid mixing up the spark plug wires.
Should I use anti-seize on the new spark plug threads?
This is a debated topic. Some plug manufacturers, like NGK, advise against it because their plugs have a special plating that prevents seizing. If you do use it, apply only a very small amount to the threads, avoiding the electrode, to prevent over-tightening.
Technical Specifications
Spark Plug Gap: 0.028" - 0.032" (0.7mm - 0.8mm)
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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.