Functions of Ignition Apparatuses and Engine Systems

An in-depth look at various ignition apparatuses and engine systems, including hot tube ignition, low-tension systems and flame ignition

| November/December 1997

Editor's Note: This is a reprint from the book Internal Combustion Engines and Tractors, Their Development, Design, Construction, Function and Maintenance. Notes of a series of lectures, delivered by Oliver B. Zimmerman, of the Engineering Staff, International Harvester Company, Chicago, copyrighted 1920, IHC. It was sent to us by Paul R. Bell, 247 Eldora do Avenue, Louisville, Kentucky 40218. 


The function of the ignition system is to provide a controlled means of firing the charge of fuel and air mixture.

Various means have been used in the past for this purpose, yielding knowledge which, owing to its value in showing development and requirements, is here reviewed.

Must Withstand High Temperature

It is well to realize something of the exacting requirements of an ignition apparatus, especially the spark plugs or igniters. First, the parts within the cylinder are subjected to the intense heats produced during ignition and burning of the charge 2000 to 4000 degrees Fahrenheit, and to sudden changes during each cycle, ranging from this exceedingly high temperature down to the cool temperature of the incoming charge of air.

Must Work Instantaneously

Next, consider the time required to complete this work. Take an engine running 600 rpm, and using spark plug ignition. It makes one revolution in 1-10th of a second. If we ignite the charge 30 degrees ahead of center, there being 360 degrees in each revolution, the time of ignition would be 30-360ths. This allows only 1-12th of the time required for one revolution or 1-120th of a second for the charge to burn and create its pressure within the cylinder a very short time even for an engine of moderate speed. In that time the spark must jump between the points, the flame start and spread throughout the cylinder to all its corners, if best results are to be obtained. If the cylinder has irregular pockets, the flame must follow into them requiring more time than if there were no pockets. This accounts for the fact that L-head and T-head engines act either slower or with less power than the valve-in-head types.

Naked Flame Ignition

The first method of firing was by igniting the mixture with a naked flame. This flame was easily and often blown out, so the engine required constant attention from the operator. The uncertainty of action quickly put this system aside in favor of hot tube ignition. Hot tube ignition consists of a piece of pipe closed at one end and screwed into the cylinder so that the inside of the tube can receive a part of the burnable mixture during compression. This tube was heated by means of a flame from the outside, thus producing the heat necessary to ignite the charge, but without the danger of blowing out the flame except in windy weather. The control had, therefore, been much improved but permanence and close regulation were still lacking.


Gas Engine Magazine A_M 16Gas Engine Magazine is your best source for tractor and stationary gas engine information.  Subscribe and connect with more than 23,000 other gas engine collectors and build your knowledge, share your passion and search for parts, in the publication written by and for gas engine enthusiasts! Gas Engine Magazine brings you: restoration stories, company histories, and technical advice. Plus our Flywheel Forum column helps answer your engine inquiries!

Be sure to take advantage of the Square Deal Subscription Program.

  • No Missed Issues.

  • No Renewal Notices.

  • No Additional Cost.

The Square Deal Subscription Program is designed as a paperless transaction with automatic renewals at a preferred low rate.   With advanced electronic notification, a 100% satisfaction guarantee and an easy opt-out plan, the Square Deal Subscription Program is the best value, risk free, eco-friendliest way to subscribe.

Facebook YouTube


Copyright 2018, All Rights Reserved
Ogden Publications, Inc., 1503 SW 42nd St., Topeka, Kansas 66609-1265