Mallory Ignition ACCEL 275, ACCEL 300 User Manual

©2007 by ACCEL

INST275/300

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275+ & 300+ STREET / STRIP

DIGITAL MULTI-STRIKE CD IGNITION CONTROLLER

GENERAL INFORMATION

The features of the 275+ and 300+ Ignitions are the same,
with one exception: the 300+ includes a single stage RPM
limiter.You can set various RPM limits using switches that
are accessible through the end plate. See page 4 of this
instruction book for more information about the rev
limiting features of the 300+.

Battery

The 275+ and 300+ Ignition Controls operate on any
n e g a t i ve ground, 12 volt electrical system with a distributor.
It will also work with 16 volt batteries and can withstand a
momentary spike of 24 volts in case of jump starts. This
system delivers full voltage with a supply of 10-18 volts,
and operates with a supply voltage as low as 8 volts.
If your application does not use an alternator, allow at least
15 amp/hour for every half hour of operation. If you crank
the engine with the same battery or other accessories,
such as an electric fuel or water pump, increase the
amp/hour rating.

Coils

For optimum performance with your 275+ or 300+ Ignition
Controls, we recommend ACCEL P/N 140019 Coil, as well
as most stock coils or aftermarket coils designed as
stock replacements or CD-type coils.

NOTE: Do not use ACCEL’s Drag Race Coil P/N 140010.

Tachometers

The green wire on the 275+ and 300+ Ignition Controls
provides a trigger signal for tachometers, shift lights, or
other add-on RPM activated devices. This wire produces a
12 volts square wave signal with a 20% duty cycle.

Some vehicles with factory tachometers may require a tach
adapter to work with the 275+ and 300+ Ignition Controls. If
your GM vehicle uses an inline filter, it may cause the tach
to drop to zero on acceleration. If this occurs, bypass the
filter. For more information on tachometers, see page 3.

Spark Plugs

Using the correct spark plug and heat range is important
for optimum performance. Because there are so many
variables to consider, we suggest starting with your engine
manufacturer’s spark plug recommendation. From there,
you can experiment with small changes in plug gap
and heat range to obtain the best performance from
your engine.

Foreign Vehicles

Because of modern fuel injection systems, some foreign
vehicles may require a tachometer/fuel injection adapter to
work with the 275+ or 300+ Ignition Controls.

NOTE: Do not install the 275+ or 300+ Ignition Controls

in any vehicle that is originally equipped with a
CD ignition control.

Spark Plug Wires

High quality, spiral wound wire and proper routing are
essential to the operation of the 275+ and 300+ Ignition
Controls. This type of wire provides a good path for
the spark to follow while minimizing electromagnetic
interference (EMI).

NOTE: Do not use solid core spark plug wires with the

275+ or 300+ Ignition Controls.

Routing

Wires should be routed away from sharp edges, moving
objects, and heat sources. Wires that are next to each other
in the engine’s firing order should be separated. For
example, in a Chevy V8 with a firing order of 1- 8 - 4 - 3 - 6 - 5 - 7-2,
the #5 and #7 cylinders are positioned next to each other
on the engine as well as in the firing order. Voltage from
the #5 wire could jump to the #7 wire. This could cause
detonation and engine damage.

For added protection against cross-fire, ACCEL offers
PRO SLEEVE insulated sleeving. PRO SLEEVE is a glass
woven, silicone coated protective sleeve that slides over
your plug wires. It also helps reduce damage from heat
and sharp objects.

MISCELLANEOUS INFORMATION

Sealing

Do not attempt to seal the 275+ or 300+ Ignition Controls.
All of the circuits of a 275+ and 30 0+ receive a conformal
coating of sealant that protects the electronics from
moisture. Sealing the 275+ and 300+ will not allow any
moisture that seeps in through the grommets to drain and
may result in corrosion.

Welding

To avoid any damage to the 275+ or 300+ Ignition Controls
when welding on the vehicle, disconnect both the 4-pin flat
and 4-pin square connectors. It is also a good idea to
disconnect the tachometer ground wire as well.

Distributor Cap and Rotor

We recommend installing a new distributor cap and rotor
when installing the 275+ or 300+ Ignition Controls. Be sure
the cap is clean inside and out, especially the terminals and
rotor tip. On vehicles with smaller caps, it is possible for
the air inside the cap to become electrically charged
causing crossfire which can result in misfire. You can
prevent this by drilling a couple of vent holes in the cap.

INSTALLATION INSTRUCTIONS

Drill the holes between terminals at rotor height, facing away
from the intake. If needed, place a small piece of screen over
the holes to act as a filter.

275+ Diagnostic LED

Behind the end panel of your 275+ ignition there is a red LED
indicator.This serves two purposes: when you first turn on
the ignition switch, the LED will flash rapidly 2 times. This
indicates that the ignition system has power, and that the
microprocessor is running properly. In addition, the LED will
flash when receiving a proper trigger signal from the vehicle.
If, after a normal power-up, the LED doesn’t flash when
cranking the engine, you should check your triggering circuit
for problems. If the LED flashes when the engine
is cranked, but there is still no spark, the problem lies
somewhere else.

275+ Cylinder Selection Only

Your 275+ Ignition comes from the factory set up for
8 cylinder operation. If you want to use this ignition with a
4 or 6 cylinder engine, you must first remove the three
screws that hold the endplate opposite the wire harness end.
Once the endplate is removed, you’ll see the end of the
circuit board. Look for the two-section switch. To select 4
cylinder mode, move the switch marked "1" to the "ON"
position. To select 6 cylinder mode, move the switch marked
"2" to the "ON" position. If both switches are "OFF", or both
are "ON", the ignition will run in the 8 cylinder mode.
See Figure 1. For operation of the 300+ cylinder selection,
see page 4.

MOUNTING

The 275+ or 300+ Ignition Controls can be mounted in any
position. If you mount it in the engine compartment, keep it
away from moving objects and heat sources. The most
convenient method for mounting is with the wire harness
end down. This ensures easy access to the cylinder selection,
and on the 300+ the rev limiter selection switches. Do not
mount the unit in a closed area, such as the glovebox.
Also, do not mount the control box next to the distributor
or spark plug wire. This will eliminate any possibility of false
trigger signals.

When you find a suitable location to mount the unit, make
sure all wires of the ignition reach their connections. Hold
the ignition in place and mark the location of the mounting
holes. Mount the 275+ or 300+ using the mounting
hardware included in the kit.

WIRING

Wire Length

All of the wires of the 275+ or 300+ Ignition Controls may be
shortened as long as quality connectors are used or soldered
in place. To lengthen the wires, use one size larger gauge
wire (16 gauge). Use the proper connectors to terminate all
wires. All connections must be soldered and sealed.

Grounds

A poor ground connection can cause many frustrating
problems. When a wire is specified to go to ground, connect
it to the chassis or engine. Always connect a ground strap
between the engine and chassis. Connect any ground wires
to a clean, paint-free metal surface.

Ballast Resistor

Remove or bypass any ballast resistor or resistor lead if
so equipped.

WIRE FUNCTIONS

Trigger and Coil Leads

Red Connects to a switched 12 volt source, such

as the ignition key.

Yellow Connects to the positive (+) terminal of

the coil.
NOTE:This is the only wire that makes
electrical contact with the coil
positive (+) terminal.

Brown Connects to the negative (–) terminal

of the coil.
NOTE:This is the only wire that makes
electrical contact with the coil
negative (-) terminal.

Trigger Wires Either of two circuits will trigger the 275+

or 300+ Ignition Controls: a points or OE
trigger circuit (white wire) or a magnetic
pickup circuit (violet and orange wires).
NOTE: The two circuits will never be
used together.

White Connects to points, electronic ignition

amplifier output or to the OE module
trigger circuit. When this wire is used, the
magnetic pickup connector is not used.

Violet/Orange Connect to factory magnetic pickups or

other aftermarket pickups. The orange wire
is positive (+) and the violet is negative (–).
When these wires are used, the white
wire is not used. Consult the chart that
shows the polarity of other common
magnetic pickups.

Green Connects to an aftermarket tachometer.

ROUTING WIRES

Route all wires away from heat sources, sharp edges, and
moving objects. Route the trigger wires separate from the
other wires and spark plug wires and direct away from the
distributor. If possible, route them along a ground plane,
such as the block or firewall, which creates an electrical
shield. The magnetic pickup wires should be routed
separately and twisted together to help reduce extraneous
interference.

FIGURE 1

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WARNING:The 275+ and 300+ Ignition Controls are
capacitive discharge ignitions. High voltage is present at
the coil primary terminals. Do not touch these terminals
or connect test equipment to them.

COMMON COLORS FOR MAG PICKUP WIRES

Distributor Mag + Mag –

Mallory Crank Trigger Purple Green
Mallory Billet Competition Distributor,
Series Nos. 81 and 84 Orange Purple
Mallory COMP® 900 0 Series Nos. 96-99 Orange Purple
Mallory Harness P/N 29040 Red Black
MSD Orange/Black Violet/Black
MSD Crank Trigger Orange/Black Violet/Black
Ford Orange Purple
Accel 46/48000 Series Orange/Black Violet/Black
Accel 51/61/71000 Series Red Green
Chrysler Orange/White Black

PRE-START CHECKLIST

• The only wires connected to the coil terminals should be
the yellow connected to coil positive (+) and brown
connected to coil negative (–).

• The red wire is connected to a switched 12 volts source,
such as the ignition key.

• If you’re not using an alternator, the battery should be
connected and fully charged.

• The engine is equipped with at least one ground strap to
the chassis.

TROUBLESHOOTING

This section offers several tests and checks you can perform
to ensure proper installation and operation of the 275+ or
300+ Ignition Controls. If you experience a problem with
your 275+ or 300+, first check for proper installation and poor
connections. You can eliminate many problems by checking
these items. If you have any questions concerning your 275+
or 300+ Ignition Controls, contact the ACCEL Technical
Service Department at 216.688.8300 ext. 5, Monday through
Friday, 8:30 am to 5:00 pm Eastern Standard time.

Tach/Fuel Adapters

If your tachometer does not operate correctly, you probably
need an ACCEL or Mallory tach adapter. Consult the
Tachometer Compatibility List at right for common
tachometers and compatible tach adapters.

No-Run on Foreign Vehicles

Some foreign vehicles with fuel injection systems may
require a tachometer/fuel injection adapter to run with the
275+ or 300+ Ignition Controls. Often, the same trigger
source is used to operate an ignition, tachometer, and fuel
injection. This results in a voltage signal that is too low to
trigger the fuel injection. A tach/fuel injection adapter will
usually solve this problem.

InoperativeTachometers

If your tachometer fails to operate with the 275+ or 300+
installed, you may need an ACCEL or Mallory tach adapter.
Before purchasing a tach adapter, try connecting your
tachometer trigger wire to the green wire of the 275+ or 30 0+
Ignition Controls. This output produces a 12 volt, square
wave. If the tach still does not operate, you will need a tach
adapter.

Two different tach adapters are available:

Mallory If you are using the magnetic pickup
P/N 29078 connector (green and violet wires) to trigger

the 275+ or 300+, you will need this adapter.

ACCEL If your tach was triggered from the coil
P/N 49365 negative terminal (voltage trigger) and you

are using the white wire to trigger the 275+
or 300+, you will need this adapter.

TACHOMETER COMPATIBILITY LIST
Aftermarket White Wire Magnetic Trigger
Tachometer Trigger Connector

Autogage 49365 29078
Autometer — —
Ford Motorsport — —
Moroso — —
Stewart 49365 29078
S.W. & Bi Torx — —
Sun 49365 29078
VDO N/A 29078
AMC (Jeep) 49365 29078
Chrysler 49365 29078
Ford (Before 1976) 49365 29078
Ford (After 1976) 49365 29078
GM Bypass in-line Bypass in-line

filter filter

Imports 49365 29078

Misses and Intermittent Problems

Experience has shown that if your engine is misfiring or
hesitating at higher RPM, it is usually not an ignition controller
problem. Most common causes include a coil or plug wire
failure, arcing from the cap or boot plug to ground or spark
ionization inside the cap. Perform the following checks:

• Inspect the plug wires at the cap and at the spark plug for a
tight connection. Visually inspect for cuts, abrasions, or burns.

• Inspect the primary coil wire connections. Because the 275+
and 300+ Ignition Controls receive a direct 12 volt source
from the battery, there will not be any voltage at the coil
positive (+) terminal, even with the key turned on. During
cranking, or while the engine is running, very high voltage
will be present and no test equipment should be connected.

WARNING: Do not touch the coil terminals during cranking
or while the engine is running.

• Make sure that the battery is fully charged and the
connections are clean and tight. If you are not running an
alternator, this is an imperative check. If the battery voltage
drops below 10 volts during a race, the 275+ or 300+
Ignition Controls output voltage will drop.

• Is the engine running lean? Inspect the spark plugs and the
entire fuel system.

• Check all wiring connections for corrosion or damage.
Remember to use proper connections followed by
soldering, then seal the connections completely.

If everything checks positive, use the procedure below to test
the ignition for spark. Mallory offers an Ignition Tester (P/N

28357) that allows you to check the entire ignition

system while it is installed in the vehicle. This tool also
checks operation of RPM limits, activated switches, and
shift lights.

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