A Guide to Spark Plug Wire Sets for the 1987 GMC R1500
Get your classic GMC truck running smoothly by choosing the right replacement spark plug wires for its V8 engine.
- Heat from the exhaust manifold is the #1 cause of wire failure on these trucks; choose a set with high-temperature silicone jackets for durability.
- For a stock daily driver, an OEM-equivalent brand like ACDelco or NGK is a reliable and cost-effective choice.
- For improved longevity, consider upgrading to a premium 8mm or 8.5mm set from brands like MSD or Taylor Cable.
- Always replace wires one at a time to maintain the correct firing order and use dielectric grease inside the boots.
Is Your Truck Telling You It Needs New Wires?
The spark plug wires on your 1987 GMC R1500 live in a harsh environment, surrounded by high engine heat. Over time, the insulation can crack and the internal conductor can break down. When this happens, you'll notice your truck isn't running like it used to. Watch for these common symptoms:
- Rough Idle: The engine may shake or vibrate more than usual when stopped.
- Engine Misfires: You might feel a stutter, hesitation, or jerking when you accelerate. This is often the most obvious sign.
- Reduced Power: The truck may feel sluggish and struggle to get up to speed.
- Worse Fuel Economy: If you're stopping for gas more often, inefficient spark could be the cause.
- Visible Damage: A visual check may reveal cracked, burnt, or melted insulation on the wires.
- Audible Ticking: In some cases, you might hear a ticking sound from the engine bay, which is the sound of electricity arcing from a cracked wire to a metal engine part.
Known Issue: Exhaust Manifold Heat
The primary known issue for these trucks is the rapid degradation of spark plug wires due to high heat from the V8 engine's exhaust manifolds. Wires routed too closely to the manifolds will become brittle and fail prematurely. Using wires with high-temperature silicone jackets and ensuring they are correctly routed through the factory wire looms is the best prevention.
Choosing the Best Aftermarket Wires for Your R1500
For a vehicle of this age, the aftermarket offers excellent, and often superior, options compared to original parts. Modern wires frequently use better materials, like silicone jackets, which offer greater heat resistance and durability. The best choice depends on your truck's condition and how you use it.
Brand Tiers
OEM-Equivalent Quality:
- ACDelco & NGK: For a stock truck used for daily driving or light work, an OEM-equivalent brand like ACDelco is a reliable and cost-effective choice. NGK is another top-tier option, known for its quality and is considered by many to be on par with original equipment.
Quality Standard Replacement:
- Delphi, Denso, Standard Wires (SMP): Brands like Delphi, Denso, and Standard offer dependable, budget-friendly options that are a good step up from generic parts-store wires. They are perfectly suitable for a standard work truck.
Premium / High-Performance:
- MSD, Taylor Cable, Accel: These brands are popular in the classic truck community. They often feature thicker 8mm or 8.5mm silicone jackets for superior heat resistance and lower electrical resistance for a hotter spark. Given the heat issues in the R1500 engine bay, upgrading to one of these sets is a smart choice for improved longevity, even on a stock engine.
Pro Tip: Silicone is Worth It
The engine bay of your R1500 generates a lot of heat. Wires with a high-temperature silicone jacket and boots will last much longer and resist damage from heat and oil better than cheaper EPDM rubber wires. This is the single best feature to look for when buying a new set.
Spark Plug Wire Set Cost for 1987 GMC R1500
| Part Type | Price Range | Notes |
|---|---|---|
| New Aftermarket | $34.69 - $196.37 | Price depends heavily on brand and features (e.g., standard vs. high-performance silicone). This range covers everything from standard replacements to premium performance sets. |
| Shop Labor | $75 - $150 | This is a relatively simple job, typically taking about an hour of labor. |
Frequently Asked Questions
What's the difference between 7mm, 8mm, and 8.5mm wires?
The measurement refers to the diameter of the wire's outer jacket. Thicker wires (like 8mm or 8.5mm) generally have better insulation, protecting against heat and preventing the spark from arcing to ground. They also often have a lower-resistance core which can deliver slightly more energy to the spark plug. For a stock R1500, a quality 8mm wire is an excellent all-around choice.
Do I need performance wires for my stock engine?
While you won't see a major horsepower gain on a stock engine, performance wires from brands like MSD or Taylor are still a good investment. Their main benefit for your truck is superior heat resistance from their silicone jackets, which helps them last much longer in the hot engine bay.
How do I make sure I don't mix up the wires during installation?
The best method is to replace the wires one at a time. Remove one old wire, match its length to a new wire from the box, and install the new wire in the same location. Then move on to the next one. This prevents mixing up the firing order, which would cause the engine to run poorly or not at all.
Should I use dielectric grease?
Yes. Applying a small amount of dielectric grease to the inside of the spark plug boots is highly recommended. It prevents the boots from getting stuck on the spark plugs, seals out moisture, and makes future replacements much easier.
Technical Specifications
The 1987 R1500 with a V8 engine uses a set of 8 spark plug wires plus one coil wire, for 9 wires total. Wires come in different diameters, typically 7mm, 8mm, or 8.5mm, with thicker wires offering better heat insulation. Most sets for this truck will feature a 90-degree boot for the spark plug end. Core materials vary from standard carbon to spiral wound stainless steel for lower resistance.
We Have This Part in Stock
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.
- GMC R1500: