Home | 1.Tecumseh Ignitions-Part 1, SSI Replacement | Part 2 Tecumseh SSI Repair | Part 3, Point Condenser Magnetos | Part 4, ESKA Twin | Att 1, How a it Works / Schematics | Att 2, Autopsies | Att 3 SSI Charge Coil and Stator Test | Att 4 Flywheel Magnets | Att 5. Replacing 610759 SSI | 2,Other Ignitions | 3. Antique Engines | 4. Vintage Generators | 5. Vintage Tractors | 6. Gaussmeter / Hall Effect | 7. Ed's Trading Post | 8. Miscellaneous
Engines&Magnets

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Update 08-Mar-2020

New Replacement Ignition, Part1, General

Background:

Dave Cave has an article “Buzz Coil-How To” in February/ March issue of Gas Engine Magazine, see

https://www.gasenginemagazine.com/restoration/gas-engines-restoration/gas-engine-buzz-coil-zm0z20fmzhur.

He uses a GM LS2 Ignition Coil, and a simple trigger circuit suitable for the low and constant RPM hit miss type engines. The spark timing would be fixed and after TDC, but instead of just one spark, it puts out a burst of sparks. The LS2 is very small, includes the electronics that was in earlier decades in a separate box and costs only $18. I got to thinking about trying the LS2 Ignition Coil triggered by the induction type of trigger that I have used for many years with the Chrysler Control Module. See GM LS2.jpg.


GM LS2.jpg

Introduction
Most small engines have only two levels of spark advance; no spark from zero to a few hundreds RPM and then an advance spark starting at a RPM where the engine won't kick back. This is simple, least expensive, but makes a compromise on timing. With the induction type trigger we have an added level of spark advance for much easier starting. It provides a spark starting at about 100 RPM that is timed at Top Dead Center, TDC for no kickback and is easier on the battery and starter motor. I chose to try the GM PC2 Crank Sensor for the trigger because I had them, but some signal conditioning is required to have them work with the LS2 Ignition Coil.

GM PC2 Modification:
The LS2 Ignition Coil is triggered by a signal form a computer. This signal is at Zero Volts until a 5 Volt pulse comes along and triggers the spark. The PC2 Crank Trigger puts out more like an AC type signal with a negative and a positive pulse. The LS2 won't like this negative pulse. This is easily fixed by routing the PC2 output thru a bridge rectifier like those used for converting the AC from the Stater to DC for charging the battery. This gives us a trigger pulse that is a doublet of two pulses.

The induction coil, PC2, has an output voltage that increases with RPM which we need for RPM control of spark timing. Voltages much higher than 5 Volts would not compatible with the LS2. So we just clip the top off the trigger signal at 5.1 Volts which is above the trigger level of the LS2. This requires a 5.1 Volt Zener diode . I am using small components so I can fit them in the PC2 connector, but have an alternative of a small box. See GMPC2Mod.jpg

GMPC2Mod.jpg

The result wave form looks like this:

WaveForm.jpg

Note that both the Advanced and the TDC trigger pulses are firing sparks at this RPM.

Installation:

The complete ignition is shown in PC2LS2Sys.jpg.

PC2LS2Sys.jpg

The wiring is very simple. The Black wires go to ground. The Red wire provides power from the battery and the Green wire from the PS2 provides the trigger signal to the Green wire on the LS2.

The PC2 needs to be mounted with .024” initial air gap to the tallest trigger pin on the flywheel. This is important because this air gap sets the voltage output thus the transition points between the three levels of spark advance. A wider air gap will increase the RPM for the first spark for both the TDC and advanced. A non-magnetic feeler gauge is shown for setting the initial air gap.

For all my testing here I used my Tecumseh HH 120 engine simulator (which is driven by a tread mill motor) since it already has the trigger pins installed. The PC2 trigger is installed on a bracket mounted where the original Solid State Ignition was and is adjusted to be aligned with the tall trigger pin on the flywheel at an air gap of .024 inches.

PC2LS2Sim.jpg

The amount of spark advance is determined by the physical location of the trigger pin on the flywheel. To the best of my knowledge, the Tecumseh HH and OH series of engines were the first to use the Trigger Pin concept for switching between levels of spark advance. The Onan NB engine uses this concept too, but with only one trigger pin since I believe it has a compression relief .

If you are using a different engine and there is no room for the PC2 , I am working on an alternate bobbin type trigger like that I used on the Briggs and Stratton ignition replacement. https://youtu.be/VS_HKaXx9JY.

In New Replacement Ignition, Part 2, Details, I plan to be addressing:

  1. PC2 Modification, fabrication of the connections to the LS2.
  2. Parts List
  3. Tecumseh Installation and initial testing
  4. Onan NB Installation
  5. Briggs and Stratton Installation
  6. Kohler Installation

Update January 2020

Why a Replacement Ignition?

One might assume that the OEM set the timing at an optimum point. I think this is not the case because compromises were made in using a single spark advance. The optimum spark advance follows a curve of increasing advance with increasing RPM. The cars in the 1970s had a centrifugal advance in the mechanical distributor. Today's cars use a crank sensor and computer to select the advance. In using an single point, the RPM for the first spark has to be delayed to a higher RPM, maybe 200 or more. This makes for hard starting. The Replacement Ignition also has a brief time of no spark, but at 70 to 100 RPM starts putting out sparks at near TDC to prevent kick back. On a sample of one, this makes for immediate starting. A second spark advance kicks in automatically at about 450 RPM.

I replaced the ignition on an old CI 10 HP Briggs and made an series of videos some may be interested in:

Part 1, Universal Ignition Replacement Installation YouTube Video Part 1

Part 2, Replacement Ignition Parts List YouTube Video Part 2"

Part 3, B&S Ignition Replacement, Addendum 1, How it works. YouTube Video Part 3

My next ignition project is to replace the ignition on a twin Briggs horizontal opposed.

Outline; This out line should help folks find what they are looking for:

Updates: 16 February 06,11 December 2009, 24 - 30 March 2012, 14 May 2019

Related Linkes:

http://www.kirkengines.com/

http://gardentractorpullingtips.com/index.htm  , Brian Miller

http://overnight-solutions.com/, Dale Colvert

http://www.abbysenior.com/mechanics/ignition.htm

http://www.wondermagnet.com/

I love playing with engines, ignition systems, magnets and old generators. My site is always under construction, but this is what I have today.

Most of the people finding their way to my website or are in search of information on Tecumseh ignitions so in this up-date, I put that first, Topic 1. I am putting the most current information first followed by the older and usually more detailed information. My playing with Tecumseh ignitions started before 1992 so the most dated information will be near the end or in attachments.

Topic1, Tecumseh Ignitions

     Background

     Introduction

     Dos and Don’ts

     Part 1, Trigger Pin SSI, 610906,610748, 610855 and Onan NB

          Testing Original Equipment

Test for Spark

Engine Kill Wire Check

Spark Plug Connector

Ignition Charge Coil

          Automotive Type Replacement Ignition

Trigger Coil

Control Module

Ignition Coil

Installation Options

Option 1 Use existing key switch

Option 2 Adding a new Toggle Switch

Option 3 Replacing the Key Switch

               Trouble Shooting Guide for all Options

               List of Materials

          Part 2, Under the Flywheel SSI, 610759 and ESKA Single Cylinder

               Initial Testing

               Dos and Dont's

               Testing Before SSI Removal

     Test for Spark

     Engine Kill Wire

     Spark Plug Connector

               Ignition Repair

     Part 3, Point - Condenser Magnetos

     Part4, ESKA Outboard Twin Cylinder

     Attachments:

          1. How a CDI or SSI Works and Schematics

          2. Autopsy of 610759 and 619906

          3. SSI Charge Coil and Stator Test

          4. Flywheel Magnets

          5. 610759 SSI Replacement

Topic 2. Other Ignitions

Topic 3. Antique Engines

Topic 4. Vintage Generators

Topic 5. Vintage Tractors

Topic 6. Gauss Meter / Hall-Effect

Topic7. Ed's Traiding Post

Topic 8. Miscellaneous

sim1.jpg
HH 120 Engine Simulator

sim2.jpg
DC motor driven Engine Simulator and Test Equipment

sim3.jpg
Testing a new Trigger Coil

dodge2.jpg
Diesel Chariot

otawa2436sm.jpg
1922 Ottawa Log Saw Engine, 4 HP

pe-75t.jpg
WWII PE-75T 1943

Thanks for dropping by and taking a look at my web site. Please get in touch with any comments or reactions! edstoller@earthlink.net .

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