1906 Rover

A guide to 6HP Rover cars


Masked ignition plugs

Friday, April 2nd, 2010

Some examples of masked ignition plugs and why they can be useful.

Masked ignition was used in several applications from the early twentieth century right through into the second world war.  Alvis and Lagonda both used this system on their cars into the 1930’s.  Its advantage is that it acts as a small combustion chamber, producing a hot stream of gas to ignite the mixture.  This causes the plugs to run hotter and cleaner.

Three types of masked ignition

Left to right:

  • A plug from an aicraft engine.  This causes the plug to run hotter in cold conditions, preventing the plug oiling up.
  • This type was sold as a ‘life-saver” for worn engines that used a lot of oil.
  • This type was fitted to some 6hp Rovers from late 1906.

End view of masked ignition cap

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