Mallory Ignition 52000 User Manual

1

52000 SERIES MAGNETIC

BREAKERLESS DISTRIBUTORS

INSTALLATION INSTRUCTIONS

AND TECHNICAL INFORMATION

FORM 1638 (REV. B) 10/04

GENERAL INFORMATION

ACCEL 52000 distributors feature a magnetic triggering device
with an adjustable mechanical advance as well as a totally
independent adjustable vacuum advance. The electronic module
is designed for use with 12-volt negative ground systems only.

ACCEL 52000 distributors are smog legal for specific applications.
Contact the factory for applications that have been granted
C.A.R.B. exemptions.

ACCEL 52000 distributors utilize an internal module and therefore
do not require an external ignition box. However, the ACCEL 52000
series distributors are compatible with most ignition amplifier
boxes (including those from ACCEL and Mallory) if a hotter spark
is required.

Distributor Cap

ACCEL 52000 distributors are supplied with a male tower clip-on
cap with HEI style spark plug wire connections and a wire retainer
ring. If a more tradition style female tower distributor cap style is
desired or required, then the ACCEL 52000 distributors can be
fitted with an ACCEL tan cap and rotor kit p/n 8120. Please note
that when changing to the traditional style female tower cap, that
it is required that you change BOTH the cap (p/n 120124) and the
rotor (p/n 130117). If a black female cap and rotor kit is desired,
then use ACCEL p/n 8124.

Spark Plug Wires

Do NOT use solid metal core spark plug wires. Suppression type
spark plug wires must be used (either carbon/graphite core or
magnetic suppression spiral core). Solid core spark plug wires will
cause false triggering and eventual module failure.

Coils

When installing your new ACCEL 52000 distributor, it is important
to check the primary resistance of the coil. To do this, use an
ohmmeter. With the ignition switch off, check across both the (+)
and (–) terminals of the coil. The resistance value should be less
than 1 ohm. If the resistance is greater than 1 ohm, you have a
coil that was designed for a factory points style distributor. Using
a coil that was designed for a points style ignition will cause the
electronic module to overheat and fail. ACCEL recommends using
a coil designed for an electronic breakerless ignition system,
which ideally, has a primary resistance of less than 1 ohm. ACCEL
coil part numbers 140001, 140008, 8145, or 8145C will work
exceptionally well with the ACCEL 52000 distributors. Please note
that an ACCEL 52000 Distributors should never be run with a CD
Coil, without the use of a CD Control Box.

NOTE: Failure to use a coil with the proper primary resistance
(less than 1 ohm) will void your warranty.

Reluctor to Magnetic Pickup Air Gap

The reluctor to magnetic pick-up air gap is preset on the ACCEL
52000 Series Distributors for optimum performance and triggering
accuracy. It does not require any adjustment.

Distributor Drive Gear

ACCEL 52000 distributors are factory fitted with a steel alloy drive
gear that is compatible with most flat tappet cams, as well as
most factory type hydraulic roller cams. Some ACCEL 52000
distributors do not include a drive gear. If your application requires
a drive gear, instructions are included on how to install your stock
drive gear onto the ACCEL 52000 distributor.

If you are using a factory hydraulic roller camshaft, we suggest
that you check for gear wear after the first 100 miles. If you are
using an aftermarket roller camshaft, you may need to use a
bronze distributor gear. Check with your camshaft supplier for
additional information.

Welding

Disconnect the ACCEL 52000 distributor wire harness before
welding on the vehicle.

Mechanical Advance

The ACCEL 52000 distributors are factory set to provide
approximately 20° degree (crank) of mechanical advance, starting
at about 900 RPM all in by about 2100 RPM. This is a good
general-purpose curve and will work for most applications. If you
engine has a higher static compression ratio or higher cylinder
pressure from a super or turbo charger, or is used in a heavily
loaded application such as a two vehicle or is equipped with
racing type components, then the mechanical advance curve may
need to be custom tailored to the your particular engines needs.

NOTE: Check local smog laws before changing the advance
curve.

Selecting and Changing the Mechanical Advance

The cams, springs, stop bushings and weights all determine the
mechanical advance curve. The starting point, amount and rate of
the mechanical advance are adjustable. When the mechanical
advance starts is controlled by the tension of the springs and their

ACCEL www.mrgasket.com

www.mrgasket.com ACCEL2

assembly out of the distributor about two inches. If necessary,
push the pick up plate back down. Now you have better access
to remove the retainer clip on the bottom of the advance
assembly, see figure #5. Install a stop bushing and reinstall the
retainer clip. If you have disassembled the shaft and advance
assembly, reassemble them in the reverse order.

Locking out the Mechanical Advance

You may also decide to run the ACCEL 52000 distributor with a
locked out mechanical advance. To do so, first remove the cap
and rotor. Remove the advance springs and weights from the
advance assembly. Remove the roll pin from the drive gear,
remove gear and thrust washer from the shaft (if so equipped).
Make sure not to misplace the roll pin and thrust washer. Lift the
shaft assembly out of the distributor about two inches. Remove
the retaining clip and the stop advance bushing, if any are
installed. Rotate the shaft assembly 180 degrees and
reposition the stop bushing pin into the small hole in the pickup
plate using a slight amount of pressure. This is a press fit to
maintain stable timing. See figure #6. Reinstall the thrust
washer, drive gear and roll pin.

Vacuum Advance

The vacuum advance operates independently from the
mechanical advance. The vacuum chamber is factory adjusted to

installed length. How quickly the mechanical advance comes in
(or the slope of the advance curve) is controlled by the stiffness of
the springs. The stiffer the springs used, the slower the rate of
the mechanical advance. The advance stop bushing controls the
total amount of mechanical advance. The larger the size of the
bushing used, the smaller the amount of total mechanical
advance. You can also lock out the mechanical advance
altogether if you wish.

The ACCEL 52000 distributors are equipped from the factory with
two heavy gold springs. The parts kit included contains three
addition pair of colored springs; black, silver and light weight
gold. See advance curve charts Figures 2A through 2D.

Selecting and Changing the Advance Stop Bushing

There are three different advance stop bushings are supplied in a
kit with the ACCEL 52000 distributor. No stop bushings are
factory installed which yields approximately 22° degrees of
advance. If a different amount of mechanical advance is desired,
see advance stop bushing chart figure #3 to select the stop
bushing that meets your requirements. To change the mechanical
advance stop bushing, first remove the cap and rotor. Although it
is not absolutely necessary, it is easier if you also remove the
advance springs and weights from the advance assembly, see
figure #4 and also remove the roll pin from the drive gear, remove
gear and thrust washer from the shaft (if so equipped). Make
sure not to misplace the roll pin and thrust washer. Lift the shaft

Curve w/2 Light Gold Springs­Set Initial Timing at 800 RPM

25

20

15

10

5

0

C
R
A
N
K
S
H
A
F
T

D
E
G
R
E
E
S

0 1,000 2,000 3,000 4,000 5,000

RPM

With No Stop Bushing

With Black Stop Bushing

With Silver Stop Bushing

With Gold Stop Bushing

FIGURE 2A

Curve w/2 Silver Springs­Set Initial Timing at 1,200 RPM

25

20

15

10

5

0

C
R
A
N
K
S
H
A
F
T

D
E
G
R
E
E
S

0 1,000 2,000 3,000 4,000 5,000

RPM

With No Stop Bushing

With Black Stop Bushing

With Silver Stop Bushing

With Gold Stop Bushing

FIGURE 2B

Curve w/2 Black Springs­Set Initial Timing at 1,600 RPM

25

20

15

10

5

0

C
R
A
N
K
S
H
A
F
T

D
E
G
R
E
E
S

0 1,000 2,000 3,000 4,000 5,000

RPM

With No Stop Bushing

With Black Stop Bushing

With Silver Stop Bushing

With Gold Stop Bushing

FIGURE 2C

Curve w/2 Heavy Gold Springs­Set Initial Timing at 1,400 RPM

25

20

15

10

5

0

C
R
A
N
K
S
H
A
F
T

D
E
G
R
E
E
S

0 1,000 2,000 3,000 4,000 5,000

RPM

With No Stop Bushing

With Black Stop Bushing

With Silver Stop Bushing

With Gold Stop Bushing

FIGURE 2D

3

ACCEL www.mrgasket.com

FIGURE 3

produce 10° advance (crank) at 10" of vacuum. The vacuum
advance can be adjusted by inserting a 3/32" Allen wrench into
the hose nipple on the vacuum chamber. Turn the wrench
clockwise to increase advance, counterclockwise to decrease.
See figure #7.

NOTE: Check local smog laws before adjusting the vacuum
advance.

In most cases, the vacuum advance hose should be connected to
a ported vacuum outlet on the carburetor. This is the same
location as stock. However, in some cases where a very large
camshaft is used, connecting the vacuum hose to full manifold
vacuum (near the bottom of the carburetor) will improve idle.

Vacuum Advance Lockout

If the vacuum advance is not going to be used (such as for
racing), the vacuum advance chamber can be removed and
replaced with the enclosed lockout. The lockout covers the hole

in

the distributor housing and prevents the pickup plate from rotating.

To remove the vacuum chamber, you must remove the distributor
gear (and lower collar if so equipped) and remove the shaft
assembly. Remove the clip holding the pickup mounting plate
assembly. Next, remove the 2 screws holding the vacuum
chamber and the clip on the control rod. Place the lockout plate
in the distributor, making sure the pin projects through the hole in
the pickup plate assembly. Secure the lockout with the 2 screws
and retaining clip. Re-assembly the distributor.

NOTE: Check local smog laws before removing the vacuum
advance chamber.

INSTALLATION

Installing an ACCEL 52000 distributor and setting the timing is
done in much the same way as a stock distributor (see a repair
manual for more information). If another distributor is already
installed (and correctly timed) note the direction the rotor is
pointing before removing the distributor. Transfer the plug wires
to the ACCEL cap in the same order and relative locations. Install

FIGURE 4

ADVANCE
WEIGHTS

ADVANCE

SPRINGS

FIGURE 6

REMOVE STOP

BUSHING IF

INSTALLED

ROTATE

SHAFT

180º

PULL

SHAFT

UP

STOP

BUSHING PIN

REMOVE

SPRINGS

REMOVE

CLIP

SMALL

HOLE

FIGURE 5

STOP BUSHING PIN

CLIP

STOP BUSHING

IF INSTALLED

BUSHING SIZE APPROXIMATE

CRANKSHAFT

DEGREES

Black- Smallest 16
Silver- Medium 12
Gold- Largest 8

C

▲

FIGURE 7

Advance Stop Bushing Chart

Changing the Advance Stop Bushing

Locking Out the Advance

ACCEL IS A DIVISION OF THE MR. GASKET PERFORMANCE GROUP
10601 MEMPHIS AVE #12, CLEVELAND, OH 44144

216.688.8300 FAX [phone]

FORM 1638

(REV. B) 10/04

Made in U.S.A.

Printed in U.S.A.

www.mrgasket.com

ACCEL4

the ACCEL 52000 distributor so that the rotor points to the same
plug wire as the previous distributor. This should make the
timing close enough to start the engine. Also make sure you
set and/or verify the initial timing advance at an engine speed
of 800 RPM.

WIRING

When you are using your distributor without an ignition amplifier
or CD type ignition unit, the 3-wire harness connects as follows:

Brown Wire Negative (-) Terminal on the Coil

Black Wire Engine Ground

Red Wire Switched 12 Volt Source

Note- Some older vehicles are equipped with a ballast
resistor or a resistance wire. These cannot be used with
this distributor. Bypass or eliminate the ballast resistor if
your vehicle is equipped with one. To check for a resistance
wire, use a voltmeter to verify that when the engine is
running that the COIL POSITIVE TERMINAL reads within 1 volt
of the battery voltage. If the voltage difference is more than
1 volt, the wire needs to be replaced. When bypassing a
ballast resistor or eliminating a resistance wire, use at least
a 14 gauge automotive grade copper wire from the COIL
POSITIVE ( + ) to the starter solenoid or a switch terminal in
the fuse box.

Make sure that your 12-Volt source supplies voltage with the
ignition key in both with the ON (run) and START positions, but
not in the ACCESSORY position.

Connecting to ACCEL 300+ Ignition

Or other CDI box, ignition amplifier, or multiple strike unit.

Your new distributor is designed as a stand-alone unit. It does not
require an external ignition/enhancer box to operate. To use the
ACCEL 300+ (or other) ignition system with this distributor, the
electronic module must be bypassed.

Step 1

Remove the cap and rotor.

Step 2

The breakerless electronic module is the green, half-circle
shaped piece with four wires attached to it. Remove the four wire
leads (one red, one green, one orange, one purple) from the
module. They are attached with spade connectors.

The module may be removed from the distributor, if desired.

Step 3

Connect the two leads from the magnetic pickup directly to the
ACCEL 300+. Connect the purple lead from the magnetic pickup
to the ACCEL 300+ purple lead (magnetic pickup positive +).
Connect the orange wire from the magnetic pickup to the ACCEL
300+ orange lead (magnetic pickup negative –).

Step 4
Other 300+ connections:

Red 12 volts key (ignition)
Black Engine Ground
Yellow 300+ Coil Positive (+)
Brown 300+ Coil Negative (–)

Step 5

Follow instructions in the ACCEL 300+ booklet regarding spark
plug gap and ignition timing under "Technical Tips and Hints"
section.

REPLACEMENT PARTS

Cap, Tan 120405
Rotor, Tan 130405

Cap and Rotor Kits:

Tan 8348
Blue 8348B
Red 8348R

Black 8348K
Electronic Module 35372
Vacuum Chamber 29332
Harness 29349
Blue & White Magnetic Pick-up 31086