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Choosing the Best Spark Plugs for Your 1987-1991 GMC V3500

For your classic GMC V3500, the best spark plug isn't the most expensive one—it's the one that matches the original engine design.

4 minutes to read 1987-1991 GMC V3500
Difficulty
2/5
Est. Time
1.5 hrs
DIY Doable?
✅ Yes
Shop Labor
$100-$200
⚠️ Drivable, but... — You can drive with worn spark plugs, but you will experience poor performance and fuel economy, and prolonged misfiring can damage other ignition components.
Key Takeaways
  • Stick with standard copper core spark plugs from ACDelco (Part No. CR43TS) or NGK for the best performance and value.
  • Avoid expensive platinum and iridium spark plugs, as they are not designed for this truck's ignition system and can cause issues.
  • Always verify the correct spark plug gap on the emissions sticker under the hood; it is likely 0.035 inches.
  • While you are replacing the plugs, it is a good time to inspect the distributor cap, rotor, and plug wires for wear.
The spark plugs in your GMC V3500 are the final, critical step in the ignition process. They receive a high-voltage electrical charge from the distributor and ignition coil and create a precisely timed spark inside each engine cylinder. This spark ignites the compressed air-fuel mixture, forcing the piston down and creating the power that turns the crankshaft. For the robust 5.7L and 7.4L TBI engines in these trucks, a strong, consistent spark is essential for smooth idling, reliable power, and efficient combustion.

Symptoms of Failing Spark Plugs

Worn-out spark plugs can cause noticeable issues in your V3500. Because these trucks have a simple and robust ignition system, they are very sensitive to plug condition. Look out for these common signs:

  • Rough Idle: The engine may shake or run unevenly when stopped.
  • Engine Misfires: You might feel a stumble or hesitation during acceleration as a cylinder fails to fire correctly.
  • Reduced Power: The truck may feel sluggish and less responsive, especially under load.
  • Poor Fuel Economy: Inefficient combustion from a weak spark forces the engine to use more fuel.
  • Difficulty Starting: Worn plugs can make it harder for the engine to fire up, especially when cold.

Is It Just the Plugs?

A "no spark" condition can also be caused by other failing ignition parts like the distributor cap, rotor, ignition coil, or the ignition control module (ICM). If new plugs don't solve the problem, these components should be inspected next.

Choosing the Right Aftermarket Spark Plug

For the Throttle Body Injection (TBI) engines in the 1987-1991 V3500, newer does not mean better. These engines were designed to run on standard copper core spark plugs. The ignition systems are not optimized for precious metal plugs like platinum or iridium, and using them can be a waste of money or even cause performance problems.

Tier 1: Recommended OEM-Style Copper Plugs

This is the best choice for the vast majority of V3500 owners. These plugs provide reliable performance and are what your engine was designed for.

  • ACDelco: As the original equipment manufacturer, the standard ACDelco copper plug is the go-to choice. The CR43TS is the most commonly cited part number and is highly recommended by owners for its reliability and correct performance.
  • NGK: NGK's V-Power copper plugs are an excellent alternative and are praised for their quality. In fact, NGK is known to manufacture some plugs for ACDelco.

Tier 2: Performance & Specialty Plugs

For modified engines or specific uses, some owners opt for different brands, but for a stock truck, these are generally not necessary.

  • Accel & MSD: These brands are known for performance ignition components and offer copper plugs that can work well, but they typically cost more than ACDelco or NGK without offering significant benefits for a daily driver.

Tier 3: Not Recommended for This Vehicle

While these are premium plugs for modern vehicles, they are not a good match for the V3500's original ignition system.

  • Bosch, Denso, Autolite (Platinum or Iridium): Owners and mechanics widely advise against using platinum or iridium plugs in these TBI engines. They offer no performance gain and can sometimes lead to a rough idle or misfires. Standard copper plugs provide a better spark in this specific application.

Check The Gap!

Always check the spark plug gap before installation, even if the box says they are pre-gapped. The correct specification for your engine is usually printed on the Vehicle Emissions Control Information (VECI) sticker under the hood. For most 5.7L TBI engines, the correct gap is 0.035 inches.

Cost of New Spark Plugs (1987-1991 GMC V3500)

Category Price Range (Set of 8) Notes
Aftermarket Copper (Recommended) $28 - $45 Includes trusted brands like ACDelco and NGK. This is the best value and performance choice.
Aftermarket Performance $50 - $175+ Includes brands like Accel and MSD. Unnecessary for a stock engine.
Aftermarket Platinum/Iridium $45 - $80+ Not recommended for this vehicle. Offers no performance benefit and may cause issues.
Shop Labor $100 - $200 Replacement is straightforward, typically taking 1-1.5 hours.

Frequently Asked Questions (FAQ)

What is the correct spark plug gap for my V3500?

The most common gap is 0.035 inches for the 5.7L V8. However, you must always verify by checking the emissions sticker under your truck's hood, as it is the most accurate source for your specific engine and year.

Why shouldn't I use expensive iridium or platinum plugs?

The ignition system in the 1987-1991 V3500 was engineered for the strong, wide spark of a copper core plug. Precious metal plugs have a fine-wire electrode that works great with modern high-energy, coil-on-plug systems, but they can provide a less effective spark in your truck's older system, leading to no benefit or even a rough run condition.

Should I use anti-seize on the spark plug threads?

This is debated. Some plug manufacturers, like NGK, plate their plugs with a material that prevents seizing and recommend NOT using anti-seize because it can act as a lubricant and cause you to over-torque the plug. If you do use it, use only a tiny amount on the threads and reduce the torque setting by about 10-15%.

How often should I change the spark plugs?

For standard copper plugs in these engines, a good interval is every 30,000 miles or every 3-4 years. Since they are inexpensive and easy to change, regular replacement is good preventative maintenance.

Are there any recalls for V3500 spark plugs?

No, there are no active or historical recalls or Technical Service Bulletins (TSBs) from GM or the NHTSA specifically related to spark plugs for the 1987-1991 GMC V3500.

Technical Specifications

OEM Part Numbers: CR43TS

Spark Plug Gap: 0.035 inches (Verify on under-hood sticker) Socket Size: 5/8 inch (16mm) 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.

Year Coverage
This article covers the Spark Plug for:
  • GMC V3500: 19871988198919901991
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