A Guide to Spark Plug Wire Sets for the 1981-1989 Chevrolet P20
Restore your P20's engine performance by choosing the right spark plug wire set.
- Symptoms of failure include rough idle, misfires, power loss, and poor fuel economy; diagnosis is based on these symptoms, not check engine codes.
- Aftermarket is the primary source; choose a quality brand like Taylor, NGK, or Denso for reliability in your P20's hot engine bay.
- Replacement is a simple, DIY-friendly job. Always replace wires one at a time to maintain the correct firing order.
- Consider upgrading to 8mm wires with 90-degree boots for better heat resistance and durability, which is beneficial for a work vehicle.
Signs of Failing Spark Plug Wires
Over time, the insulation on your P20's spark plug wires breaks down from heat and age. When this happens, the electrical energy can leak out before it reaches the spark plug, causing performance issues. Watch for these common symptoms:
- 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 properly.
- Difficulty Starting: Weak or inconsistent spark can make the engine hard to start.
- Poor Acceleration and Power Loss: The engine will feel sluggish and less powerful than usual.
- Reduced Fuel Economy: Inefficient combustion from weak spark means the engine uses more fuel.
- Visible Damage: Check the wires for cracks, melting, or burn marks, especially where they might touch hot engine parts.
A Note on Check Engine Lights
Vehicles from this era (1981-1989) have very basic or no onboard diagnostic systems (OBD-I). A check engine light is unlikely to illuminate for failing wires, and if it does, it will not specify which cylinder is misfiring. Diagnosis relies on observing these physical symptoms.
Choosing the Right Aftermarket Spark Plug Wires
For a vehicle like the P20, original equipment (OEM) AC Delco wires are largely unavailable as new old stock. The aftermarket is your primary source, offering a wide range of quality and performance. The key is to choose a set that can handle the heat and demands of your P20's engine bay.
Brand Quality Tiers
Here’s how the available brands generally stack up based on reputation for use in classic Chevy V8s:
Performance & Heavy-Duty Tier
These brands are known for robust construction, excellent heat resistance, and low electrical resistance for a stronger spark. They are a great choice for a hard-working P20 step van.
- Taylor Cable: A highly-regarded brand known for durable, thick (often 8mm) silicone wires that provide great performance and longevity.
- FAST / MSD: Top-tier performance brands offering very low resistance wires for maximum spark energy. MSD wires are frequently praised for quality and reliability in performance applications.
Standard / OEM-Quality Tier
These brands are the go-to for reliable, stock-level performance. They are a dependable choice for a daily driver or standard-duty vehicle.
- NGK: Known for making high-quality OEM parts, their wire sets are a solid, reliable, and affordable choice.
- Denso: Similar to NGK, Denso is a trusted OEM supplier with a reputation for quality and proper fit.
- Standard Wires (SMP): Standard Motor Products is a long-standing aftermarket manufacturer known for producing quality replacement parts that meet or exceed original specifications.
Economy & Mixed-Review Tier
These brands can be a budget-friendly option, but quality can be inconsistent. They may be suitable for a vehicle that sees light use.
- Accel: This brand has a mixed reputation. While they offer high-performance options with heat-resistant ceramic boots, some users report issues with poor build quality and premature failure.
- Prenco / Walker Products: These are standard aftermarket brands that offer a functional, budget-friendly replacement.
Pro Tip: Consider wires with 90-degree spark plug boots. On a V8 engine, this can help with clearance around the exhaust manifolds, reducing the risk of melting the boots. Also, using a small amount of dielectric grease inside each boot will prevent them from getting stuck on the spark plugs and make future replacement easier.
Estimated Replacement Costs
The cost to replace spark plug wires on a 1981-1989 P20 is reasonable due to the simple engine design and easy access.
| Item | Estimated Cost |
|---|---|
| Aftermarket Spark Plug Wire Set | $30 - $108 |
| Shop Labor | $65 - $125 |
| Total Estimated Cost (Installed) | $95 - $233 |
Note: Costs are estimates and can vary by location and the specific parts chosen.
Frequently Asked Questions
Should I choose 7mm or 8mm wires?
Stock wires are typically 7mm. Performance-oriented wires are often 8mm or larger. The thicker wire has more insulation, which can improve durability and heat resistance, and sometimes offers lower electrical resistance. For a P20, either will work, but an 8mm wire from a quality brand like Taylor can be a good upgrade for durability.
What are spiral core wires?
Most modern performance wires use a spiral core. A conductor is tightly wound around a central core (like Kevlar). This design provides low resistance for a strong spark while suppressing the radio frequency interference (RFI) that can cause static in your radio. This is superior to old carbon core wires which had higher resistance.
Do I need special tools to replace spark plug wires?
No special tools are required. A spark plug wire puller can be helpful to avoid damaging the wires, but you can usually remove them by twisting and pulling firmly on the boot. The most important rule is to replace one wire at a time to ensure you don't mix up the engine's firing order.
Can I replace just one broken wire?
While you can replace a single wire to fix an immediate problem, it's not recommended. Spark plug wires degrade at a similar rate. If one has failed, the others are likely near the end of their service life. Replacing the full set ensures reliable performance and prevents future misfires.
Technical Specifications
The Chevrolet P20 from this era was commonly equipped with a 5.7L (350ci) V8 or a 4.8L L6 engine. Spark plug wire sets are specific to the engine type. Most aftermarket sets feature a spiral-wound core for low resistance and RFI suppression. Wire diameters are typically 7mm (stock) or 8mm+ (performance). Sets come with pre-attached boots, often with 90-degree bends for the spark plug side to aid in clearance.
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.
- Chevrolet P20: