Denso 671-8040 Spark Plug Wire Set

Denso 7mm Spark Plug Wire Set for Classic GM Ignition

Denso 671-8040 is a 7mm spark plug wire set built to match factory-installed wire sets in form, fit, color, and performance. It is a direct replacement for classic Chevrolet and GMC ignition systems that use 7mm wires, including applications such as Chevrolet Corvette, Impala, Bel Air, and GMC vans.

Key Features

• 7mm insulation outside diameter for OE-style ignition wire routing and fitment
• Silicone spark plug boot material for heat resistance and flexibility
• 90-degree spark plug end boot for tight engine bay routing
• Female spark plug end terminal type with male distributor/coil end terminal
• Built to meet or exceed OE/OES standards for construction and performance
• Denso First Time Fit product line for factory-style replacement applications

Product Details

The Denso First Time Fit line is focused on direct replacement ignition components that mirror the original wire set specifications. Part number 671-8040 uses 7mm insulation and silicone boots to maintain consistent electrical routing and dependable connection points in older GM ignition systems. This makes it a practical choice for owners restoring or maintaining Chevrolet Corvette, Chevrolet Impala, Chevrolet Bel Air, and related GMC applications that call for a 7mm wire set.

This part cross-references NAPA Mileage Plus 6718040 for the same application.

What It Helps Address

• Misfires caused by worn or deteriorated spark plug wires
• Hard starting related to weak ignition transfer
• Intermittent spark loss from cracked insulation or damaged boots
• Routing issues in engines that require 90-degree spark plug boots
• Restoration needs for OE-style ignition appearance and fit

Installation Notes and Tips

Verify the vehicle uses a 7mm ignition wire set before ordering. Confirm distributor and spark plug terminal styles match the male distributor/coil end and female spark plug end configuration. On classic Chevrolet Corvette, Chevrolet Impala, and GMC applications, route each wire away from exhaust heat and moving components, and replace wires one at a time to preserve firing order.

Quality Assurance

Denso states that First Time Fit ignition wire sets are engineered to match factory-installed wire sets in form, fit, color, and performance, with construction that meets or exceeds OE/OES standards.