Lesson plan

Headless engine

A headless engine or fixed-head engine is an engine where the end of the cylinder is cast as one piece with the cylinder and crankcase. The most well known headless engines are the Honda GC, historical examples include the Fairbanks-Morse Z and the Witte Headless hit-and-miss engine. In the 21st century, light-duty consumer-grade Honda GC-family small engines use a use such a design, termed 'uniblock' by Honda. One reason for this, apart from cost, is to produce an overall lower engine height. Being an air-cooled OHC design, this is possible thanks to current aluminum casting techniques and lack of complex hollow spaces for liquid cooling. The valves are vertical, so as to permit assembly in this confined space. On the other hand, performing basic repairs becomes so time-consuming that the engine can be considered disposable.

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Article summary

A headless engine or fixed-head engine is an engine where the end of the cylinder is cast as one piece with the cylinder and crankcase. The most well known headless engines are the Honda GC, historical examples include the Fairbanks-Morse Z and the Witte Headless hit-and-miss engine. In the 21st century, light-duty consumer-grade Honda GC-family small engines use a use such a design, termed 'uniblock' by Honda. One reason for this, apart from cost, is to produce an overall lower engine height. Being an air-cooled OHC design, this is possible thanks to current aluminum casting techniques and lack of complex hollow spaces for liquid cooling. The valves are vertical, so as to permit assembly in this confined space. On the other hand, performing basic repairs becomes so time-consuming that the engine can be considered disposable.

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  1. Summarise the article in your own words. Which single claim would you verify first, and why?
  2. Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
  3. If two sources disagreed about one of these facts, what would you need in order to trust one over the other?

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