Spark Plug Wire Set Guide for the 1970-1978 American Motors Gremlin
Get the right spark plug wires for your Gremlin's inline-6 or V8 engine.
- For a stock 1970-1978 Gremlin, a quality OE-style wire set from Standard, NGK, or Walker is a reliable and cost-effective choice.
- If your Gremlin has performance upgrades like headers or a high-energy ignition, consider low-resistance wires from MSD, Accel, or Taylor for maximum spark.
- Always buy the correct wire set for your engine (I6 or V8) to ensure proper fit and wire count.
- Replacing spark plug wires is a simple DIY job that can be done in under an hour with basic tools.
Signs of Failing Spark Plug Wires
Old spark plug wires can cause a number of noticeable engine problems. Because the materials degrade from heat, vibration, and time, the electrical current can weaken or escape before it reaches the spark plug. If you notice any of these issues, your wires might be the culprit.
- Rough Idle: The engine may shake or vibrate more than usual when stopped.
- Engine Misfires: You might feel the engine stutter or hesitate while driving. This happens when a cylinder fails to fire correctly.
- Engine Hesitation: The car may feel sluggish or slow to respond when you press the gas pedal.
- Difficulty Starting: Weak spark can make it harder for the engine to turn over, especially in cold or damp weather.
- Visible Damage: Check the wires for cracks, burns, or melting insulation. Sometimes you can see a blue spark jump from a bad wire to a metal engine part in the dark.
Choosing the Right Aftermarket Wires
For a classic car like the 1970-1978 Gremlin, original OEM spark plug wires are no longer available. Aftermarket parts are your only option, but the good news is that modern technology often makes them better than the originals. Wires today have better insulation and conductivity than what was available in the 1970s. The choice comes down to what you want for your Gremlin: a stock-style replacement or a performance upgrade.
Brand Quality Tiers
The brands available can be grouped into two main categories based on their design and purpose.
| Tier | Brands | Best For |
|---|---|---|
| Performance | MSD, Accel, Taylor Cable | Owners looking for maximum spark energy for modified engines or high performance. These wires have very low resistance. |
| OE-Style Replacement | Standard Motor Products, NGK, ACDelco, Denso, Walker Products | Daily drivers and classic restorations. These wires are designed to meet or exceed original specifications and provide reliable performance with excellent radio noise suppression. |
A Note on Performance Wires
Performance wires from brands like MSD and Accel have very low electrical resistance to deliver the hottest spark possible. While this is great for power, it can sometimes cause electromagnetic interference (EMI), which you might hear as static or buzzing on an AM/FM radio. OE-style wires are designed specifically to suppress this interference.
Brand Details
- MSD & Accel: These are top names in performance ignition. They offer low-resistance wires that deliver a strong spark, which is ideal for engines with other performance upgrades. Accel also offers wires with ceramic boots that can withstand very high temperatures, perfect for cars with aftermarket headers.
- Taylor Cable: Known for making quality wires for race cars and street machines, Taylor offers durable, high-performance options. Some users have had great success, while others have reported issues, so inspect them carefully.
- Standard Motor Products (SMP): A highly recommended brand for OE-style replacements. Forum users suggest buying their standard line (often in a red box) and avoiding the budget "T-Series."
- NGK: A top-quality Japanese brand that makes excellent OE-replacement wires. They are known for their durability and excellent noise suppression. They offer universal "cut-to-fit" sets that are great for vintage cars.
- Walker Products: This brand offers a direct, specific-fit set for the Gremlin, ensuring an easy installation without cutting.
Direct-Fit vs. Cut-to-Length
Some wire sets, especially performance ones from MSD or universal sets from NGK, are "cut-to-length." This means you get a roll of wire and the ends, and you assemble them yourself for a perfect custom fit. Other sets are "direct-fit," meaning they are pre-cut and ready to install right out of the box. If you want a simple installation, choose a direct-fit set made for your Gremlin's specific engine.
Frequently Asked Questions
Do I need special wires for my Gremlin's V8 engine?
Yes. The V8 engine requires a set with 8 spark plug wires plus a coil wire. The inline-6 engines need a set with 6 spark plug wires plus a coil wire. The lengths will also be different. Always verify the engine in your Gremlin before ordering.
Are more expensive spark plug wires better?
Not necessarily. More expensive performance wires (like MSD or Accel) are better for high-performance engines but may be overkill for a stock daily driver. A quality OE-style set from a brand like Standard or NGK will provide excellent, reliable performance for most owners.
How often should I replace my spark plug wires?
There is no exact interval, but many manufacturers suggest replacement every 60,000 to 100,000 miles. For a classic car like the Gremlin, it's best to inspect them regularly for any signs of wear, cracking, or melting insulation and replace them if they look damaged or if you're experiencing symptoms of failure.
What does the wire diameter (e.g., 7mm, 8.5mm) mean?
The diameter refers to the thickness of the outer insulation jacket. A thicker wire (like 8.5mm) offers more insulation to prevent voltage leaks and can be more durable, especially in high-heat engine bays with aftermarket headers. For a stock Gremlin, a standard 7mm or 8mm wire is perfectly adequate.
Technical Specifications
Varies by engine (Inline-6 or V8) and brand. Wires can be direct-fit or cut-to-length. Diameter typically ranges from 7mm to 8.5mm. Core can be carbon fiber (for RFI suppression) or spiral wound (for low resistance).
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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.