Which spark plug is the best for my Model A Question

Spark plugs have always been a subject of conversation amongst car enthusiast. Model A fans are no exception. Which spark plug is the best for my Model A is usually the result of the discussion.

Henry Ford chose to install Champion 3X spark plugs in all new Model A’s. The term “heat range regarding spark plugs refers to temperature produced by the spark plug at combustion time. Compression ratio and fuel mixture are factors in choosing the heat range. The Model A Ford engine has approximately a 4.2:1compression ratio which is very low considering modem engines. And the fuel mix ratio is generally on the rich side. This calls for a spark plug with relatively high heat range. The 3X was an excellent choice.

While Champion 3X spark plugs are still available but they are quite expensive. In the $25 range each. There are, however, alternative spark plugs that are available at a much lower price and can function as well as the 3X. The Champion Wl8 is the closest match to the 3X and will perform equally as well.

The Wl8 and 3X are shown side by side so that tip length can easily be compared.. Of course, with a high compression head the heat range can be slightly cooler than the 3X. Checking the performance by looking at the tip of the spark plug is a good way to determine which heat range performs best in your engine. A White tip is a plug too hot, Black tipis too cold. Brown/gray is just right.

Tips from “the Know”
from Technical Editor by Paul Koncak