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Adjustable Billet By-Pass Regulator-3/8" NPT

Adjustable billet by-pass return style fuel pressure regulator 3/8" NPT Boost Reference - 1:1

PART# 12-879

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$166.00   Suggested Retail
$148.95   Your Price
Estimated shipping date: 05/14/2021
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Holley Billet Fuel Pressure Regulators are part of a complete line of fuel system products from Holley. They are precision machined from 6061-T6 billet aluminum for strength and durability. These regulators are adjustable from 4-65 psi and will handle both carbureted and EFI applications. A second pressure spring is included allowing you to increase the fuel pressure range up to 65 psi for EFI systems. They are offered with two port sizes, 3/8" NPT or 6AN to adapt to your new or existing fuel lines. So, if you are currently running a carbureted system but plan to upgrade to EFI in the future, these regulators will have you covered either way.


  • Adjustable from 4-65 psi for precise fuel pressure adjustments
  • Constructed of billet aluminum with a black anodized base and a clear anodized top for good looks
  • Used in systems with a return line back to the tank
  • (1) 3/8” NPT Inlet; (1) 3/8” NPT Outlet; and (1) 3/8” NPT Return Port
  • Includes fitting for manifold reference
  • Includes an 1/8 NPT gauge port
  • Boost Reference - 1:1
  • The 4-15 psi carbureted spring comes installed in the regulator
  • Compatible with diesel fuel and E85


Emission Code5
Fuel SystemEFI/Carb
Fuel TypeGasoline
Inlet Size3/8 inch NPT
Outlet Size3/8 inch NPT
Product TypeFuel Pressure Regulator
Return Size3/8 inch NPT
WarrantyLimited 90 Day
Part Number12-879



This part is legal for sale or use on Emissions Controlled Vehicles, Uncontrolled (Non-Emissions Controlled) Vehicles, and Racing Use Only Vehicles because it does not affect vehicle emissions and is not covered by emissions regulations.

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