FORM 1455 (REV. C) 3/00 INSTALLATION INSTRUCTIONS AND TECHNICAL INFORMATION ® RETURN LOG PART NO. 4302 FIGURE 1 DUAL FEED HOLLEY CARB (VACUUM SECONDARY, DOUBLE PUMPER, OR DOMINATOR) SEALING GASKET – 2 PLACES (NOT SUPPLIED) FUEL LINE FROM FUEL PUMP UP TO 550 HP: AN-8 OR 1/2" HARDLINE UP TO 800 HP: AN-10 OR 5/8" HARDLINE UP TO 1200 HP: AN-12 OR 3/4" HARDLINE HOLLEY TO AN-8 COUPLER – 2 PLACES RETURN LINE SIZE UP TO 180 GPH PUMP: AN-8 OR 1/2" HARDLINE UP TO 360 GPH PUMP: AN-10 OR 5/8" HARDLINE UP TO 720 GPH PUMP: AN-12 OR 3/4" HARDLINE AN-8 TO 3/8" NPT ADAPTER – 2 PLACES O-RING – 2 PLACES FUEL LOG EXTENSION REGULATOR ASSEMBLY FUEL LINE FROM FUEL PUMP RETURN LINE BACK TO FUEL TANK IN 1/8 NPT GAUGE PORT – 2 PLACES (PLUGS SUPPLIED) O-RINGS 1. Mallorys fuel return log features a built-in adjustable return regulator. The pressure can be adjusted while the engine is running. There are no shims to change and the fittings do not need to be loosened to adjust the pressure. The pressure is adjusted by loosening the jam nut and turning the adjustment screw. 2. Fuel pressure is adjustable between about 3 PSI and 12 PSI. Exact range depends on the size of the fuel pump and return line size. 3. All fittings are included. The center-to-center distance of the outlets is adjustable to allow use on most Holley carbs. PRESSURE ADJUSTMENT SCREW JAM NUT AN-10 FITTING – 2 PLACES 6. If AN-8 (or 1/2" hardline) fuel lines are used, the AN-10 fitting(s) can be replaced with AN-8 fittings (such as Earls PN 985081). 7. Assembly is shown with the inlet at the rear of the carb. Assembly can be flipped over so that the inlet is near the front. IMPORTANT NOTE This fuel log is assembled with o-rings for use with gasoline. O-rings are also included for use with alcohol fuel. If you use alcohol fuel, disassemble the Mallory Return Log and replace the installed o-rings with those supplied. 4. Thread sealant may be necessary on the 3/8" NPT fittings and on the 1/8" NPT gauge ports. 5. Repair kits are available and include all necessary O-rings. These kits can be used for repair, or to convert from gasoline to alcohol or from alcohol to gasoline. Use Kit #3173 for gasoline applications. Use Kit #3174 for alcohol applications. Lubricate O-rings prior to assembly. --OVER-- 9. Because Mallorys Return Log 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 or 500 pumps), place a plug in the bypass outlet. 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 Fuel Log (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. ® 70, 110, OR 140 PUMP BYPASS PLUNGER PAD BYPASS PLUNGER BYPASS SPRING (DISCARD) BYPASS SPACER BYPASS PLUG JAM NUT 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 1455 (REV. C) 3/00 Made in U.S.A. Printed in U.S.A.