Gates 31670 Fuel Tank Cap

Locking Fuel Cap for Classic GM and Dodge Applications

The Gates 31670 Regular Locking Fuel Cap is built for vehicles that need a secure, emission-controlled fuel tank seal. It combines lockable protection with a two-way pressure relief and vacuum relief valve to let the tank breathe while helping contain fuel vapors.

Gates’ Regular Locking Fuel Cap line is focused on OE-style fuel system service for older domestic vehicles, including many Chevrolet, Dodge, Buick, Pontiac, Oldsmobile, Cadillac, GMC, Chrysler, Ford, Lincoln, and Mercury applications. This Gates 31670 fuel cap is a direct-fit option for a wide range of classic trucks, vans, and passenger cars that use a regular locking cap design.

Key Features

• Lockable regular fuel cap design for added fuel tank security
• Emission control venting to support Federal and State requirements
• Two-way pressure relief and vacuum relief valve
• Deep cam construction for proper engagement
• Thread diameter: 1.38 in.
• Shell diameter: 2.63 in.
• Depth: 1.88 in.
• OE-style replacement for many vintage fuel tank cap applications

Detailed Description

The Gates 31670 is a regular locking fuel tank cap engineered to meet OEM specifications while maintaining the fuel system’s required venting function. Its emission-control design helps the tank breathe during pressure changes and reduces the escape of fuel fumes. That makes it a practical choice for restoring proper sealing on older vehicles that rely on a locking cap with controlled venting.

Compatible With classic applications such as 1975-1978 Chevrolet C10, 1975-1980 Dodge D150, and 1971-1974 Pontiac Firebird, this cap also cross-references Wix 46338 and Hayden 292 for the same application. The Gates 31670 is a useful replacement when the original cap no longer seals correctly or the locking mechanism has worn over time.

What This Fuel Cap Helps Solve

• Fuel vapor odor from a cap that no longer seals properly
• Loose or worn locking fuel cap retention
• Check-engine or emissions-related issues tied to cap sealing on older systems
• Pressure buildup or vacuum-related tank breathing problems
• Fuel tank contamination from a damaged or missing cap

Installation Notes and Tips

Verify the cap style, thread diameter, shell diameter, and cam type before installation. This part uses a deep cam design and emission-control venting, so it should be matched to the vehicle’s original fuel filler neck and emissions setup. For best results, compare the existing cap to the listed dimensions and confirm the vehicle-specific notes, especially on models with cab tanks, California emissions equipment, or wagon exclusions.

Fits 1975-1978 Chevrolet C10, 1975-1980 Dodge D150, and 1971-1974 Pontiac Firebird applications as listed in the fitment data, along with many other classic GM and Chrysler vehicles.

Quality Assurance

Gates manufactures this locking fuel cap to meet OEM specifications and Federal and State emission requirements. The design includes a pressure relief and vacuum relief valve to support proper fuel system operation while maintaining a secure, emission-controlled seal.