Fargo W200 Pickup Spark Plug Replacement Guide: 1966-1972
Get your classic Fargo's Slant-6 or V8 engine running smoothly with the right set of new spark plugs.
- Stick with standard copper-core spark plugs from Autolite or Champion for best performance with the stock ignition system.
- The single most important step is to set the spark plug gap to 0.035 inches before installation.
- Know your engine (225 Slant-6 or 318 V8) to ensure you purchase the correct set of plugs.
- Replacing spark plugs is an easy DIY job that can be completed in under an hour with basic tools.
Symptoms of Failing Spark Plugs
Without modern computer diagnostics, Fargo owners need to rely on listening to and feeling how their truck runs. Worn or fouled spark plugs will cause noticeable issues. If you experience one or more of these symptoms, your plugs are a likely culprit.
- Rough Idle: The engine may shake or sound uneven when the truck is stopped and idling. You might feel vibrations that weren't there before.
- Engine Misfires: You may feel a hesitation, stumble, or jerk from the engine, especially when accelerating or pulling a load. This happens when a cylinder fails to fire correctly.
- Hard Starting: The engine may take longer than usual to crank and start, especially in cold weather. A weak spark struggles to ignite the fuel mixture.
- Reduced Power & Acceleration: The truck may feel sluggish or like it has lost its get-up-and-go. Incomplete combustion robs the engine of power.
- Worse Fuel Economy: If you find yourself visiting the gas station more often, failing spark plugs could be the cause. An inefficient spark leads to wasted fuel.
Choosing the Right Aftermarket Spark Plug
For a classic truck like the 1966-1972 Fargo W200, newer technology isn't always better. The original ignition systems were designed for traditional copper-core spark plugs. Sticking with this type is the best approach for reliability and performance.
Copper is King for Your Classic
Your W200's stock ignition system operates at a lower voltage than modern vehicles. It was designed for standard copper-core spark plugs. While expensive platinum and iridium plugs last longer, they require higher voltage to create a strong spark and may not perform as well in your truck's original setup. For the best results, use copper plugs and plan to change them as part of a regular tune-up every 10,000 to 20,000 miles.
Brand Quality: Autolite vs. Champion
For these vintage Mopar engines, the line between "OEM" and "aftermarket" is blurry. Champion was often the original equipment supplier for Chrysler during this era. However, many classic truck owners have personal preferences based on their experiences.
- Champion: The traditional choice for many Mopar enthusiasts. They were designed for these engines and are a reliable option.
- Autolite: A very popular alternative. Many owners report their engines run smoother and more reliably with Autolite plugs, citing good quality and performance.
Ultimately, both Autolite and Champion produce quality copper-core plugs that will work well in your Fargo. You can't go wrong with a fresh, properly gapped set from either brand.
Know Your Engine and Check the Gap!
Before buying, confirm if your truck has the 225 Slant-6 or the 318 V8 engine, as the exact plug part number may differ. The most critical step is to set the spark plug gap before installation. For a stock ignition system on either engine, the correct gap is 0.035 inches. Do not trust the plugs to be gapped correctly out of the box. Use a feeler gauge or gapping tool to check and adjust every single plug.
Aftermarket Spark Plug Cost for 1966-1972 Fargo W200
| Part Type | Price Range (Per Plug) |
|---|---|
| New Aftermarket (Copper Core) | $3.50 - $9.31 |
| Shop Labor | $60 - $120 |
Pricing is an estimate and may vary by location and retailer.
Frequently Asked Questions (FAQ)
What is the correct spark plug gap for my Fargo W200?
For a 1966-1972 Fargo W200 with a stock ignition system, the recommended spark plug gap is 0.035 inches for both the Slant-6 and V8 engines. Always verify this with a gapping tool before you install new plugs.
How often should I change the spark plugs?
For standard copper plugs, which are the correct type for your truck, a good interval is to inspect them every 10,000 miles and replace them every 10,000 to 20,000 miles as part of a regular tune-up.
Is Autolite or Champion better for my truck?
While Champion was often the original brand, many owners now prefer Autolite, reporting excellent, reliable performance. Both are solid choices. The best approach is to install a new set of properly gapped copper plugs from either brand and see how your engine responds.
Is replacing the spark plugs a difficult job?
No, this is a very easy job for a DIY mechanic. The engines in these trucks provide ample space to access the spark plugs with basic hand tools. The entire job can typically be done in under an hour.
Technical Specifications
Spark Plug Gap: 0.035 inches (for stock ignition systems) Plug Type: Standard Copper Core
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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.