MSD Ignition 8485 User Manual

AUTOTRONIC CONTROLS CORPORATION • 1490 HENRY BRENNAN DR., EL PASO, TEXAS 79936 • (915) 857-5200 • FAX (915) 857-3344
Installation Instructions
MSD Billet VW Distributor
PN 8485
Important: Read these Instructions before attempting the installation.
Contents
Timing Functions
Choosing an Advance Curve
Setting or Locking Out the Centrifugal Advance
Installing the Distributor
Wiring the Distributor
Parts Included In This Kit
1 Billet Distributor
2 #10 Disc Washers
3 Advance Stops
1 Retaining Nut
7 Shims
1 Clamp Stud
4 Advance Springs
1 Hold Down Bracket
2 O-Rings
TIMING FUNCTIONS
Before continuing with the installation, here are a few definitions you should be
aware of:
Initial Timing: This is the base timing of the engine before centrifugal advance
begins.
Centrifugal Advance: The centrifugal advance mechanism is made up of weights,
springs, advance cam, and an advance stop bushing. The amount and rate of
advance that your distributor is capable of is determined by the centrifugal timing.
If you ever wish to lock out the centrifugal advance, refer to the centrifugal advance
section.
Total Timing: This is the total of the initial timing plus the centrifugal advance added
together. Example: 10° Initial + 25° centrifugal = 35° Total Timing.
CHOOSING AN ADVANCE CURVE
The function of the advance curve is to match the ignition timing to the burning rate
of the fuel and speed (rpm) of the engine. Any factor that changes the burning rate
of the fuel or the engine speed can cause a need for an ignition timing change.
Figure 1 shows some of the factors that will affect engine timing.

MSD Ignition 8485 Specifications

General

Brand	MSD Ignition
Model	8485
Category	Automobile Accessories
Language	English

Summary

Installation Instructions

Timing Functions

Defines initial, centrifugal, and total timing concepts for engine performance.

Choosing an Advance Curve

Explains how engine factors influence ignition timing curves and performance.

Tips on Selecting an Advance Curve

Provides practical guidance for setting optimal initial and centrifugal ignition advance.

Centrifugal Advance Curve

Details the mechanism and customization options for centrifugal advance.

Selecting the Advance Springs

Explains how springs affect advance rate and customization of the curve.

Installing the Advance Springs

Step-by-step guide for removing and installing distributor advance springs.

Selecting the Advance Stop Bushing

How to choose bushings for desired centrifugal advance degrees based on charts.

Changing the Advance Stop Bushings

Step-by-step instructions for replacing the distributor's advance stop bushing.

Locking Out the Centrifugal Advance

Procedure to disable or prevent centrifugal advance from functioning.

Installing the Distributor

Detailed steps for physically mounting the distributor into the engine.

Wiring

Instructions for correctly connecting the distributor to the ignition system.

Service

Details product service, warranty claims, and return procedures.

Limited Warranty

Outlines the product's one-year warranty terms and limitations.