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