OVERVIEW
This kit permits all previous Radium Engineering adjustable fuel pressure regulators to be converted to an RA-Series FPR. This will add all of the newest features as well as performance enhancements to older regulators. 

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FUEL PRESSURE ADJUSTMENT

RA-series regulators feature the first tool-less pressure adjustment. A jam nut and set screw are no longer required. With a simple turn of the knob, pressure will be increased or decreased. 

To aid in adjusting pressure, there are incremental detents that provide haptic feedback to the user. Every detent permits 1psi (+/-0.5psi) of adjustment depending on current fuel pressure.

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FUEL PRESSURE STABILITY
With years of track and bench testing data, the RA-series regulators have been refined to optimize pressure management. A newly designed single stainless steel return orifice generates laminar flow that enhances stability control.

Minimum Pressure: 18.5psi (1.3bar)
Maximum Pressure: *N/A
*This is rhetorical. The maximum pressure is dependent on the relief valve inside the pump or the maximum current the fuel pump controller allows. 

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ABOUT FUEL PRESSURE DROP AFTER SHUTOFF
Some installations may experience a rapid fall of fuel pressure when the engine and/or fuel pump shuts off. This is considered normal operation for aftermarket fuel pressure regulators, regardless of brand. 

This can occur due to the diaphragm seat and the return orifice not fully sealing when fuel flow is stopped. For regulators to have the ability to regulate high fuel flow rates, the size of these components must be increased. This creates larger sealing surfaces between the components, preventing them from forming a perfect seal, even with high spring rates. This is not an indication of an issue or defect and it is not a cause for concern on its own. You do NOT need to contact technical support about this issue. Fuel pressure will reset immediately when the fuel pump is activated again.

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1:1 RISING RATE VACUUM REFERENCE
RA-series regulators feature a 360 degree swiveling vacuum reference port that is double O-ring sealed. This is the first in the industry. It permits the installer to quickly point the vacuum fitting in any direction with no tools required.

There are 4 interchangeable #10-32 threaded vacuum port fittings provided to cover all scenarios. 

1. Barbed Fitting: A black zinc-plated 3/16" (5mm) barb machined from high strength steel that is compatible with the following vacuum hoses: 5/32" (4mm), 3/16" (5mm), and 7/32" (6mm).
2. 3AN Male Fitting: A black zinc-plated adapter machined from high strength steel that is compatible with 3AN hose ends.
3. Push-To-Connect: A nickel-plated brass fitting with Buna-N O-rings that is compatible with hard plastic 1/4" OD tubing.
4. Vacuum Plug: A black oxide stainless steel screw that is used to maintain a constant (non dynamic) fuel pressure. Beginning in the mid 1990s, vehicle manufacturers started transitioning to returnless fuel systems to lower EVAP emissions. To keep temperatures lower, these regulators are mounted inside the tank and do NOT have the ability to be vacuum referenced. This plug would be required in this scenario.

NOTE: When installing the vacuum fitting, it is recommended to use a wicking medium-strength threadlocker.

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FUEL COMPATIBILITY
This RA-series conversion kit is suitable with all gasoline types including unleaded, leaded, oxygenated, and pre-mixes. Furthermore, they are compatible with alcohol blends of fuel including methanol, ethanol, and E85. 

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INCLUDED
-Upper Rotating Assembly
-5mm Barbed Vacuum Fitting
-Vacuum Plug Fitting (Returnless)
-1/4' Push-To-Connect Vacuum Fitting
-3AN Male Vacuum Fitting
-Anodized Half Moon Retainers (x2)
-Stainless Steel Return Orifice
-Stainless Button Head Screws (x5)
-Stainless Steel Spring
-Fluorosilicone Diaphragm