Mallory 4305M Instruction Manual

FORM 1527 (REV. B) 06/01

INSTALLATION INSTRUCTIONS

®

COMPETITION

FUEL PRESSURE REGULATOR

FOR FUEL INJECTION

PART NO. 4305M

IMPORTANT: This regulator must use a fuel return line. The fuel return line runs between the fuel
bypass port of the regulator and the fuel tank. Fuel pressures cannot be adjusted if the fuel return
line is absent.

PARTS INCLUDED IN THIS KIT

1 Fuel Pressure Regulator
1 Bracket
2 Bracket Mounting Screws
2 3/8" NPT Pipe Plugs
2 AN-8 Fittings
2 O-rings for Fittings

SPECIFICATIONS:

Port thread sizes: 3/8" NPT and AN-8

Adjustment range: 30-100 PSI

Fuel Application: Gasoline and Alcohol/Methanol

VACUUM/BOOST
COMPENSATION PORT (3/16"
O.D. BRASS BARB FITTING)

GENERAL INFORMATION

Mallorys 4305M regulator regulates fuel pressure between high pressure
fuel pumps and fuel injection systems. The regulator is recommended for
Mallory COMP PUMP
produce 30-100 PSI.

The 4305M regulator is a return style fuel pressure regulator. The excess
fuel and fuel pressure is sent back to the fuel tank through the fuel return
line. The fuel return line runs between the fuel bypass port of the regulator
and the top of the fuel tank. The fuel tank must have provisions for a fuel
return line.

This regulator is equipped with a vacuum/boost compensation port (brass
barb fitting) that can be used to momentarily decrease fuel pressure
(vacuum compensation) at idle and part throttle, or increase fuel pressure
under blower boost (boost compensation). While it is not necessary to
connect a hose to the vacuum/boost compensation port, it may be
beneficial in some cases. However, the small plug on the barb must be
removed before use.

You can mount the 4305M regulator at any angle. For maximum
efficiency, mount it as close as possible to the fuel injection system. DO
NOT mount the regulator on or near exhaust manifolds. A bracket is
provided for convenient mounting.

®

60FI, 110FI, or any fuel injection pump designed to

ADJUSTMENT SCREW

JAM NUT

REGULATOR CAP

OUTLETS TO INJECTION
(3 PLACES, 3/8" NPT)
UNUSED PORTS MAY BE
PLUGGED OR USED AS
GAUGE PORTS

BRACKET MOUNTING HOLES (2)

REGULATOR HOUSING

INLET PORT FROM PUMP (AN-8)

FUEL BYPASS PORT (AN-8)

INSTALLING THE 4305M REGULATOR

1. Connect the fuel line and the return line. The return line
must be attached to the bottom port on the regulator. The
fuel line must be attached to the upper -8AN port on the
regulator. Fittings must be purchased to adapt the fuel
line and the return line to the regulator. The unused port(s)
in the regulator can be plugged or used as gauge port(s).

2. Turn the fuel pump on and check for leaks. If leaks are
found on the NPT (tapered) fittings, make sure the threads
are covered properly with Teflon sealer.

NOTE: If the fuel system will not prime properly, back
the adjustment screw all the way out of the regulator
until the system is primed. Then reinstall the adjust­ment screw.

3. Connect the vacuum hose that was originally connected
to the stock regulator to the small nipple on the Mallory
regulator. This will reduce fuel pressure at idle and during
light-throttle cruise.

4. Set the fuel pressure. Loosen the jam nut on the top of
the regulator and turn the brass adjustment screw to ad­just the pressure. Clockwise increases pressure.

FUEL LINE SIZE (FROM PUMP TO REGULATOR)

Fuel line size is determined by the horsepower of the en­gine.

Up to 350 HP: 5/16" or 4AN
Up to 500 HP: 3/8" or 6AN
Up to 700 HP: 1/2" or 8AN
Up to 1200 HP: 5/8" or 10AN

RETURN LINE SIZE

The size of the return line is determined by the output of
the fuel pump.

Up to *29 gal/hr (110 liter/hr): 1/4" or 3AN
Up to *45 gal/hr (170 liter/hr): 5/16" or 4AN
Up to *90 gal/hr (340 liter/hr): 3/8" or 6AN
Up to *180 gal/hr (680 liter/hr): 1/2" or 8AN

* Pump output at 40 psi.

PUMP SIZE

Pump size is determined by horsepower.
Multiply horsepower by .083 to determine pump size in gal-

lons per hour.

Example: 500 HP x .083 = *42 gal/hr

Multiply horsepower by .314 to determine pump size in li­ters per hour.

Example: 500 HP x .314 = *157 liters/hr

*Pump output at 40 psi.

NOTE: Add 25% larger pump for supercharged
applications.

MALLORY IS A DIVISION OF THE MR. GASKET PERFORMANCE GROUP
550 MALLORY WAY, CARSON CITY, NEVADA 89701
[phone] FAX [phone]
www.mrgasket.com

FORM 1527

(REV. B) 06/01

Made in U.S.A.

Printed in U.S.A.