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Classics 101: An Introduction to Classic Cars
The articles are presented with the permission of the publishers and authors with full credits on each.
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Spark Plugs
by Harry Wolk

Time to start thinking of getting our Classics ready for the road. Good performance is dependent on several factors, one being spark plugs. It is easy to remove your spark plugs and clean them. The condition of the spark plug tells a multitude of stories about your engine. Spark plugs with encrusted black carbon is the most common problem.

Cleaning with steel wool is better than nothing. Using a spark plug sand blaster gives the best cleaning. However, this encrusted black carbon is a sign of problems. The causes of this condition may be a cold type of plug, which is proper if you are using the car for long road trips. If all you are doing is driving the car off and on a trailer or around the block or to the bank and back, change to a hot plug.

Excessive oil reaching the combustion chamber, especially at slow or idling speeds, is also a frequent contributor. A hot plug temporarily may solve the problem, but excessive oil is a sign of other problems, as in bad rings or pistons.

If some of the plugs are clean and others have dry sooty lamp black deposits, the sooty plugs are getting too much gasoline, and can be corrected with carburetor adjustments. If a leaner mix is used, and the engine runs irregularly or misfires, go back to original setting and consider a hotter plug.

Incorrect gaps also contribute to fouling, and is attributed to too narrow a gap. Check the gap and published specs on your car and re-gap all plugs. While space does not allow for expansion into other areas causing spark plug problems, the above comments may get you on the road with nominal effort.

Courtesy of Northern Lights of the Ohio Region