Diesel spark conversion

Hey guys, anyone know of a company that makes a spark conversion that could be used on around a 25 HP Yanmar or Kubota engine to run on wood gas? Thanks in advance for any information you have.

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I’ve been meaning to investigate this Kenneth. Getting ready for winter has taken most of my time right now but I know that MSD makes a lot of alternate ignition systems. This is mostly racing equipment and pricey. I know hardly anything about ECU systems but I think someone that did could adapt a module from some car or truck to use on a diesel to provide sequential spark.

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Kubota themselves offer up their small engines factory converted to gasoline, propane or natural gas in your power range. Their “WG” series of engines. I’ve operated two versions of these. Having a labeled “Special Gas Cylinder Head” (all standard diesel lower end including the pistons). These having flywheel triggering spark ignition systems; individual to each cylinder ignition coils; and a Denso micro-processor controller.
Be very expensive to parts one retrofitting.

Here is a link to how you can make up a conversion system based on either Chrysler, Ford or GM parts:
You’ll have to scroll halfway down the page and start reading; picture and diagrams examining at the flashing “Caution”.
Do not be put off that Brian Miller is a small engine guy.
These style conversions can run up to 12 cylinder engines. Great doomsday systems.
Ford module based: and the proper GM amplifier-module and you’ll have a one-wire switchable 10 degree set-back; or set forward spark timing capability.
Enough for a generator engine.

Adapting in spark plugs with an machined insert would be up to you. Just straight forward mini-lathe hobbyist work.

Steve Unruh


Thanks for the reply Steve. Reason i was asking about those 2 particular engines is i have a Kubota ZD326 mower that has one of their 3 cylinder diesels and a Polaris side by side with a Yanmar diesel both engines are about 24 to 25 HP i think so since im somewhat familiar with those engines thought they would be good ones to work on. Problem of course is they are so expensive to buy those engines especially for a project.


Humm, after first telling me that the link is dangerous -
my system says the garden tractor pulling tips site doesn’t exist…

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Yes I know this is what has happen now RonO.
Like someone, or Ones; does not want this info findable.
Like patent conversion module sellers have trolled-spammed links to his site, maybe.

Downright triggers a paranoia reflex, eh.
Just makes me real pissed off determined then to find a work-a-round way.


Bummers. I think it was a site I came across some 3 years ago and had saved a link to on my old computer.


Hey Ron and others:
In your own net search system, search up:
“A1 Millers Small Engine & Specialty Shop”
Find his site out of Columbia, MO
Open it up.
Go down to the third shown box of information links to:
"Conventional (Points and Condenser) Ignition Parts, Flywheel - and Crank-Trigger Electronic Ignition . . . "
The info is there.


What the heck? Search A1 Miller’s and the tractor puller site pops up. Here is the catalog. Yes - that is the site I remembered.


Here is a write up Ken Boak did nearly 10 years ago. It includes schematics for the ignition circuits he designed and info on the principals. Individual circuits could be used with separate hall sensors and magnets spaced about a flywheel so that each magnet sweep is in a different plane than the others - thus having individual ignitions for each cylinder.


Thanks, that sounds very obtainable.


I checked with Ken Boak. He did not make the system adaptable to multiple cylinders. It was solely intended for the Lister. He suggests using an ignition system from an 90’s car. The mid 1980-90’s Yugo 4 cylinder engine used a Bosch distributor ignition system. This was a typical distributor complete with both centrifugal and vacuum advance with Hall effect trigger. The control/ignition coil driver was mounted on the fender and the fender served as a heat sink. It used what appeared to be a typical vintage type 12v ignition coil. The Chevy Sprint from the same time frame had a 3 cylinder engine and thus may have a usable distributor ignition for a 3 cylinder conversion.
Possibly the Lister ignition system can be used with multiple cylinders by adding separate amplifier circuits to coil driver output. This would be wasted spark. One amplifier circuit or channel for each cylinder’s ignition coil. This would allow having a single flywheel trigger. I think that it would work with a pre-combustion chamber design as there likely would not be sufficient compression of the fresh air/fuel charge on a 3 cylinder to have fresh charge in the pre-combustion chamber of the next cylinder in the firing order. If there was sufficient charge - or it was an open chamber engine - then there may possibly be premature ignition of the next cylinder in the firing order.

Many diesel injection pumps have a tachometer drive that possibly could be adapted to drive a distributor. I have some engines where there is a cover over the injection pump drive gears. It is removed during service to set the injection timing. A custom cover could be made to support a distributor equipped with a drive coupler.