Spark Plugs for the 1966-1972 Fargo D110 Pickup: A Complete Guide
Keep your classic Fargo running strong by choosing the right spark plugs for its specific engine.
- For the 1966-1972 Fargo D110, standard copper spark plugs from Champion or Autolite are the best choice.
- The most common engines are the 225 Slant-Six and 318 V8; ensure you buy the correct plugs for your engine.
- A rough idle, hard starting, and poor acceleration are key symptoms of failing spark plugs.
- Changing spark plugs is a simple DIY job on these trucks that requires only basic tools.
Signs of Failing Spark Plugs
Worn or fouled spark plugs can cause several noticeable problems in your 1966-1972 Fargo D110. Because these trucks have simple ignition systems, they are very sensitive to spark plug condition.
- Rough Idle: The engine may shake or sound uneven when you're stopped.
- Hard Starting: The engine cranks for a long time before it finally starts, or it may not start at all.
- Engine Misfires: You might feel a hesitation or stumble from the engine, especially under acceleration. This is often due to a plug failing to fire correctly.
- Reduced Power: Your truck may feel sluggish and slow to accelerate.
- Worse Fuel Economy: When plugs don't fire efficiently, your engine uses more fuel to do the same amount of work.
Choosing the Right Aftermarket Spark Plugs
For a vintage truck like the Fargo D110, you don't need expensive, fancy spark plugs. Standard copper-core plugs work perfectly and are what the engines were designed for. Both Autolite and Champion offer excellent, affordable options.
Brand Tiers: Champion vs. Autolite
Historically, Chrysler vehicles, including Dodge and Fargo trucks, came from the factory with Champion spark plugs. Many purists and long-time mechanics stick with Champion, believing they are best suited for Mopar engines. They are a reliable, OEM-style choice that will restore original performance.
Autolite is another trusted American brand that offers a high-quality, value-priced alternative. Their standard copper plugs provide excellent performance and are a popular choice for classic vehicles. Some owners and mechanics prefer Autolite, citing consistent quality right out of the box. You can't go wrong with either brand for your Fargo truck.
Pro Tip: Check the Engine
Before you buy, confirm which engine your truck has. The most common were the 225 cubic inch "Slant-Six" and the 318 cubic inch V8. Both engines use different spark plugs, so it's important to order the correct part for your specific engine to ensure proper fit and performance.
Known Issues for This Vehicle
There are no official recalls or Technical Service Bulletins (TSBs) from NHTSA for spark plugs on the 1966-1972 Fargo D110. This is normal for a vehicle of this age. However, owners have reported a few common issues:
- Oil Fouling on Slant-Six: The Slant-Six engine is known for its valve cover gasket leaking oil directly into the spark plug wells, which can foul the plugs and cause misfires. When changing your plugs, it's a good time to check for oil leaks in that area.
- Incorrect Plug Reach: Using a spark plug with threads that are too long can cause serious problems. The exposed threads can accumulate carbon, making the plug difficult to remove later, or in the worst case, the plug could contact the piston. Always double-check that you have the correct part number for your engine.
Aftermarket Spark Plug Cost (1966-1972 Fargo D110)
| Part Type | Price Range (Per Plug) | Notes |
|---|---|---|
| Aftermarket Spark Plug | $3.50 - $9.31 | Standard copper plugs from brands like Autolite and Champion are in this range. |
Frequently Asked Questions (FAQ)
How often should I change the spark plugs on my Fargo D110?
For these classic engines using standard copper spark plugs, a good rule of thumb is to inspect them every 15,000 miles and replace them every 30,000 miles or every 2-3 years, whichever comes first. Given the age of the vehicle, regular checks are more important than just mileage.
Do I need to gap the spark plugs?
Yes. Even if the plugs say they are "pre-gapped," you should always check the gap with a feeler gauge and adjust it to your truck's specifications. The correct gap for most of these engines is 0.035 inches, but always verify with a service manual if possible.
Should I use anti-seize on the threads?
This is a debated topic. If you choose to use it, apply only a very small amount to the middle of the threads, ensuring none gets on the electrode. Many modern plugs have a special coating that prevents seizing, making anti-seize unnecessary. Over-torquing is a bigger risk when using anti-seize.
What tools do I need to change the spark plugs?
You will need a ratchet, a spark plug socket (typically 13/16-inch for these trucks), an extension, and a spark plug gap tool. A can of compressed air is also helpful to clean out debris from around the old plugs before you remove them.
Technical Specifications
Engine compatibility: 225 cu. in. Slant-Six, 318 cu. in. V8. Common Aftermarket Part Numbers: Autolite 65, Autolite 85, Champion 404. Socket Size: Typically 13/16 inch. Standard Gap: 0.035 inches.
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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.