5.3 Ignition settings 5 SETTING UP A BASIC CONFIGURATION
5.3.1 Basic Trigger
The distributor is the traditional method of timing spark and distributing the high-tension spark voltage to individual
spark plugs. Originally, this used a set of breaker points, a condenser and a single ignition coil. Most distributors
feature mechanical and vacuum advance systems to match spark timing somewhere close to optimal for different
operating conditions. Later systems were "breakerless" and replaced the high-maintenance points with VR, hall or
optical sensors, but there is still just one tooth for each cylinder. When combined with OEM fuel injection systems,
the distributor may be "locked" in that there is no advance mechanism and the timing is controlled by the computer.
Any engine predating fuel injection will have the tach pickup within the distributor. With most distributors there is
no cylinder identification so it is not possible to run sequential fuel; Ford Signature PIP TFI distributors, which used
one short vane and the others a different length, are the exception.
This mode also covers arrangements with a single crank wheel with one tooth for every two cylinders, where
there is no cam sensor used. This looks exactly the same to the ECU - other than that the signal is more accurate.
Ford TFI and GM computer controlled are specialized versions of the distributor system and will be covered
in their own sections. “Basic Trigger” does not cover “dual sync” distributors, which have two pickups and use
“Toothed Wheel” mode, or setups which have a distributor but use a more complicated trigger pattern than the
basic “one tooth, one cylinder.” There are covered in their own sections.
Examples of ignitions that use “Basic Trigger” include:
• Ford TFI
• GM HEI (both original and computer controlled)
• Chrysler Lean Burn
• MSD distributors and Flying Magnet
In all cases, you’d wire the Crankshaft Position In wire to the distributor pick-up, and Spark A Out to an ignition
module.
5.3.1.1 Input phasing In most cases you will be controlling timing with the MS3Pro; for this you need a trigger
that does not vary angle with rpm or load. This is called a "locked distributor".
Early distributors such as points, original HEI, Duraspark etc, all have advance mechanisms built in. Similar
distributors can be converted for use with MS3Pro:
• Remove ignition module (if present)
• Connect pickup sensor (VR, hall, optical, points) to MS3Pro.
• Remove and weld up mechanical advance mechanism.
• Remove vacuum canister.
• Use remnants of vacuum advance mechanism to achieve correct input:output phasing. You may be able to
set the rotor output phasing FIRST and then rotate the baseplate to achieve the correct input phasing.
Later engines may feature a distributor in conjunction with computer controlled timing - usually these distributor are
"locked" from the factory and should already have good input and output phasing. (e.g. Ford TFI, GM computer
controlled, Bosch hall effect.) Align as per the factory manuals and determine how it is phased before you modify
anything!
The crank angle at which the tach input triggers is of importance and needs to be configured in the MS3Pro. It
can be really helpful to install timing tape on your crank pulley or temporarily mark on a range of angles. For best
spark control, there are some optimal and some disallowed crank angles. A typical engine will have an operating
advance range of approximately 10-50° BTDC timing (depending on engine type.) If the trigger angle is within this
range of angles, you will not be able to get a full range of timing advance.
Some trigger angles work better than others. If you end up with an invalid trigger angle, adjust the distributor
(the engine will often run with an invalid angle set, but will not be able to get a full range of advance).
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 60
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