Add to Favorite Sellers. Holley 12-842 HP Billet Carbureted By Pass w/ Idle Bleed Fuel Pressure Regulator. Street/Strip Carbureted Applications Two Port Adjustable from 4.5 to 9 PSI with Idle bleed; 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. They feature a black bright dip anodized body and a clear bright dip anodized top for corrosion resistance and good looks. The Holley 12-842 fuel pressure regulator features 3/8 NPT in/out ports and a 3/8 NPT return port. Customer Service & Feedback. So we have a chance to make it right – we want your repeat business! Check out the official Holley Performance. For more great deals!!