WHY YOU SHOULD CHANGE SPARK PLUGS EVERY YEAR.

By 0. C. RHODE, Chief Engineer, Champion Spark Plug Co.

If you, a car owner, could visualize clearly the difference that old and new spark plugs cause in the combustion chamber of your engine, there would be no question in your mind concerning the advisability and actual economy of installing a complete new set of spark plugs in your car every lo,000 miles, or at least once a year.

With a new set you would see a hot, intense spark applied to the gas mixture, causing complete combustion and leaving only the burned gas to escape through the exhaust. Such a spark and such combustion mean that your engine is developing its maximum power from the fuel used—that it is performing as it was designed and intended to perform. With a set used for a year, or ro,000 miles, you would see a weak spark delivered to the gas mixture. This

results in only partial combustion of the charge, and the final ejection, through the exhaust valve, of a large part of that still unburned gas. You see good power being shot into the air, a sluggishness in your engine, greater oil consumption, slower speed, rapid carbon formation on the pistons and valves, and an actual loss in fuel.

This lesser performance is bound to occur with any make of spark plugs, even those with two-piece, gas-tight construction, special alloy electrodes, sillimanite core and semi-petticoat tip, which withstands the tremendous engine stress and retards carbon formation.

That is why it is real economy to install a complete set of new spark plugs at least once a year. They pay for themselves in oil and gasoline saved, without considering at all the improved general engine performance.