FORM 1548 (REV. A) 05/02 INSTALLATION INSTRUCTIONS ® INLINE RETURN REGULATOR PART NO. 4316 1. Mallorys Inline Return Regulator is an adjustable bypass style fuel pressure regulator designed to regulate pressure in a carbureted fuel system. FIGURE 1 2. The regulator must be mounted in the return line. For best results, the regulator should be mounted within 3 feet of the carburetor(s). See Figure 3 for typical installations. 3. Fuel pressure is adjusted by loosening the jam nut and turning the adjustment screw. The adjustment range is approximately 3-12 PSI. Exact range depends on the size of the fuel pump and return line (see Figure 1). 4. This regular is designed to work with pumps up to 300 GPH. 5. Fittings are included to connect the regulator to 8AN fuel lines. Alternate fittings may be used to connect the regulator to other sizes/types of fuel lines. 6. Repair kits are available and include all necessary o-rings. These kits can be used for repair, or to convert from gasoline to alcohol. FEED LINE SIZE Up to 500 HP: 6AN or 3/8" Hardline Up to 750 HP: 8AN or 1/2" Hardline Up to 1250 HP: 10AN or 5/8" Hardline RETURN LINE SIZE Up to 90 GPH: 6AN or 3/8" Hardline Up to 200 GPH: 8AN or 1/2" Hardline Up to 300 GPH: 10AN or 5/8" Hardline Use Kit #3173 for gasoline applications Use Kit #3174 for alcohol applications. Lubricate o-rings prior to assembly. 7. This regulator is assembled with o-rings for use with gasoline. O-rings are included for use with alcohol. If alcohol fuel is used, disassemble the regulator and replace the o-rings with those supplied. 8. Because this is a return style regulator, the bypass at the pump must be disabled. If you are using a pump with an external bypass (such as Mallory 250), place a plug in the bypass outlet. ® 70, 110, OR 140 PUMP FIGURE 2 If you are using a Mallory 70, 110, or 140 pump, the bypass spring must be replaced with the bypass spacer included with this regulator (see Figure 2). Replace the spring with the spacer. Apply thread sealant to the bypass plug and tighten the plug until snug. Do not overtighten. Replace and tighten the jam nut (see Figure 2). If you are using a non-Mallory pump, contact the manufacturer for information on how to disable the bypass. --OVER-- FIGURE 2 TYPICAL INSTALLATIONS MALLORY IS A DIVISION OF THE MR. GASKET PERFORMANCE GROUP 550 MALLORY WAY, CARSON CITY, NEVADA 89701 (775) 882-6600 FAX (775) 887-4326 www.mrgasket.com FORM 1548 (REV. A) 05/02 Made in U.S.A. Printed in U.S.A.