Mallory Ignition 4305M User Manual

FORM 1527 (REV. D) 01/12

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 by pass 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

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® 60FI, 110FI, or any fuel injection pump designed
to produce 30-100 PSI.

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

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.

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)

MALLORY IGNITION www.mallory-ignition.com

REGULATOR HOUSING

INLET PORT FROM PUMP (AN-8)

FUEL BYPASS PORT (AN-8)

1

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
thread 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): 5/16” or –4AN

Up to *45 gal/hr (170 liter/hr): 3/8” or –6AN

Up to *90 gal/hr (340 liter/hr): 1/2” or –8AN

Up to *180 gal/hr (680 liter/hr): 5/8” or –10AN

*Pump output at 40 psi.

PUMP SIZE

Pump size is determined by horsepower.

Multiply horsepower by .083 to determine pump size in
gallons 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 TRADEMARK OF PRESTOLITE PERFORMANCE
10601 MEMPHIS AVE. #12, CLEVELAND, OH 44144

216.688.8300 FAX [phone]

2 www.mallory-ignition.com

FORM 1527

(REV. D) 01/12

Made in U.S.A.

Printed in U.S.A.