® INSTALLATION INSTRUCTIONS 5-PORT RETURN STYLE FUEL PRESSURE REGULATOR SERIES 4300/4301 Mallory's 5-Port Return Style Fuel Pressure Regulator is Both regulators are adjustable from 5 to 18 PSI at a flow recommended for high volume applications (250-500 rate of 500 GPH. To adjust pressure, loosen the jam nut GPH). This regulator is available in two models: and turn the adjustment screw. Clockwise rotation increases pressure. • Series 4300, designed for gasoline applications • Series 4301, designed for alcohol applications NOTE: Adjusting fuel pressure higher than 7 PSI on carbureted engines may cause carburetor flooding and For best efficiency, the regulator should be mounted as possible fire. close as possible to the carburetor. PRESSURE ADJUSTMENT SCREW JAM NUT VACUUM/BOOST COMPENSATING PORT #8 AN (5-PLC'S) CAN BE USED AS INLET FROM PUMP OR OUTLET TO CARB. MOUNTING SCREWS (2) (#10 AN) CAN BE USED AS INLET FROM PUMP OR OUTLET TO CARB. USE AS INLET FROM PUMP WHEN USING HIGH VOLUME FUEL PUMPS (IN EXCESS OF 250 GPH) RETURN TO FUEL TANK (#10 AN) USE SAME SIZE RETURN LINE AS INLET LINE NOTE: A bypass at the fuel pump is not required for this regulator. When using this regulator with Mallory Series 5250 or 5500 fuel pumps, the fuel return port at the pump should be plugged. FORM 1077 (REV. A) 10/97