Denso 3075 Spark Plug

Denso 3075 U-Groove Spark Plug Overview

The Denso 3075 is a conventional spark plug built for dependable secondary ignition performance in older Chevrolet, GMC, and Jeep applications. Its U-groove ground electrode design is engineered to improve ignitability, helping support more efficient combustion in engines that call for a standard copper-core plug.

The Denso U-Groove Conventional line focuses on practical OE-style ignition performance with a design that promotes a stronger spark path. For drivers servicing classic Chevrolet Corvette, El Camino, Bel Air, and Impala applications, this plug offers a straightforward replacement option with the correct thread, reach, and seat style.

Key Features

• U-groove ground electrode tip design for improved ignitability
• Conventional spark plug construction for standard ignition systems
• Copper center electrode core material for reliable heat transfer
• Nickel center and ground electrode tip materials
• Pre-gapped to 0.7 for specified applications
• 14.00 mm thread diameter with flat seat design
• 20.6 hex size and 09.50 reach
• Manufacturer heat range 20

Product Details

Denso 3075 is part of the U-Groove Conventional product line, a spark plug family built around a ground electrode shape that helps expose the spark to the air-fuel mixture more effectively. That design can improve ignitability in engines that rely on a traditional plug layout, making it a practical choice for maintenance on vintage trucks, vans, and passenger cars. This part cross-references DENSO Auto Parts (e.g., W20S-U) for the same application.

Compatible With 1957-1961 Chevrolet Corvette, 1957-1959 Chevrolet Bel Air, 1959 Chevrolet Impala, 1959-1960 Chevrolet El Camino, 1964-1967 Chevrolet El Camino, 1967-1971 GMC G15/G1500 Van, 1967-1970 GMC G25/G2500 Van, 1971 GMC G35/G3500 Van, 1968-1970 Chevrolet Blazer, 1968-1970 Chevrolet C10 Suburban, 1968-1970 Chevrolet C20 Suburban, 1968-1970 Chevrolet K10 Suburban, 1968-1970 Chevrolet K20 Suburban, 1968-1971 Jeep CJ5, and 1970-1971 GMC Jimmy.

Common Issues This Spark Plug Can Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from inconsistent ignition at the plug gap
• Misfire complaints in older carbureted engines
• Reduced throttle response from weak spark delivery
• Maintenance replacement for aged conventional ignition components

Installation Notes and Tips

Verify the thread diameter, reach, seat type, and heat range against the engine specification before installation. The Denso 3075 uses a flat seat and 14.00 mm thread, so it should be matched to the correct cylinder head design. Check the gap against the engine requirement during service, and inspect ignition wires, distributor components, and coil condition at the same time for consistent results.

Quality Assurance

Denso is known for OE-level ignition component engineering, and the U-Groove Conventional line is built to meet the needs of standard replacement service on classic applications. The Denso 3075 is specified for direct-fit use in listed Chevrolet, GMC, and Jeep models when the engine calls for this plug configuration.