Radium Engineering Remote Mount SVF Swing Valve Filler Cap

OEM-Style Capless Filler for Radium Silver Cup Fuel Filler Receptacles

The Radium Engineering RAD20-1548 SVF Swing Valve Filler Cap threads directly into any Radium "silver cup" fuel filler receptacle and converts it to capless OEM-style operation. The spring-loaded swing valve door, sealed by an O-ring, stays positively closed when no nozzle is present and opens automatically under standard nozzle pressure, keeping vapor in and debris out. An optional dust cap and tether are included. This filler is NOT compatible with Radium Dry-Break fuel fillers.

Key Features

• Threads directly into any Radium "silver cup" fuel filler receptacle for capless operation
• Spring-loaded swing valve door with O-ring seal stays closed when no nozzle is inserted
• Opens automatically under standard pump nozzle pressure, no manual operation required
• Modeled after OEM capless fuel filler designs for familiar, reliable operation
• CNC machined billet aluminum construction for long-term durability
• Optional dust cap and tether included for added protection during race storage and transport
• Universal compatibility with all Radium silver cup filler receptacles
• NOT compatible with Radium Dry-Break fuel fillers

Specifications

What's Included

• Radium Engineering RAD20-1548 SVF Swing Valve Filler Cap
• Optional dust cap
• Dust cap tether

Frequently Asked Questions

This cap threads into any Radium "silver cup" fuel filler receptacle. The silver cup design is Radium's standard screw-in filler cup used across their fuel cell, surge tank, and remote filler builds. If your Radium filler setup uses the silver cup receptacle format, this cap will thread in and convert it to capless operation.

No. This cap is not compatible with Radium Dry-Break fuel filler systems. Dry-Break applications require their own dedicated Dry-Break cap. If you are unsure which filler receptacle your system uses, check the Radium Engineering product listing for your filler kit before ordering this cap.

The spring-loaded swing valve door is held closed by constant spring tension against an O-ring seat. This creates a positive seal that keeps fuel vapor inside the tank and prevents dirt, moisture, and debris from entering the filler neck between fuel stops. The door opens automatically when a standard fuel nozzle is pressed against it and snaps back closed when the nozzle is removed.

Yes. The swing valve is sized and spring-rated to open cleanly under standard fuel pump nozzle pressure, both full-size and small-bore nozzles. No special nozzle or adapter is required. It operates exactly like the OEM capless fillers found on many late-model vehicles.

The included dust cap provides an additional physical barrier against dirt and debris during race transport, track storage, or off-road use where the filler opening may be exposed to heavy contamination. The tether keeps the cap attached to the filler neck so it is not misplaced during a fuel stop. Using the dust cap is optional but recommended for any application where the filler is not sheltered from the environment.

Yes. If your existing Radium filler receptacle currently uses a traditional screw-on cap, this cap threads directly in as a drop-in upgrade to capless operation. No modification to the receptacle is required. This is a straightforward way to upgrade the fill experience on an existing fuel system without replacing the entire filler neck assembly.

Yes. The billet aluminum construction and O-ring materials used in this cap are compatible with gasoline and E85. For dedicated methanol or fuel blends beyond E85, confirm compatibility with Radium Engineering directly before installation, as material ratings can vary with more aggressive solvents.

This filler cap is sold as an individual filler cap unit, including the optional dust cap and tether. The Radium silver cup filler receptacle it threads into is a separate component. If you are building a new filler system from scratch, you will need to purchase the appropriate Radium silver cup receptacle and filler neck separately.

Installation Overview

1. Confirm that your existing Radium filler receptacle is the silver cup style and is not a Dry-Break compatible receptacle before proceeding.
2. Remove any existing cap from the silver cup receptacle by unscrewing counterclockwise.
3. Thread the cap clockwise into the silver cup receptacle by hand until snug, then tighten to a firm fit. Do not overtighten.
4. Attach the dust cap tether to the filler neck body at a convenient anchor point.
5. Test the swing valve operation by pressing a fuel nozzle against the door to confirm it opens cleanly and snaps shut when released.
6. Perform a fill test to verify no leaks at the threaded connection before returning the vehicle to service.

WARNING: This product can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.