My Model A engine used Blue Crowns, the spark plugs that powered Indy champions

The spark plug is commonly viewed as a disposable afterthought; only when they cause problems do we deign to think of these humble but hardworking pieces of porcelain and steel. The plugs I found in my recently revived Model A Ford were two-tone and marked with a brand name that I didn’t immediately recognize—Blue Crown.

This piqued my interest, and it turns out these Blue Crown plugs are neat pieces of history that tie my Model A (extremely loosely) to the Indianapolis 500. 

The Blue Crown Spark Plug company was based in Chicago during a time when the automotive aftermarket was in bloom. It was a subsidiary of Motor Master Products, which is believed to have distributed a range of more than 90 different spark plug brands during the 1930s and ’40s. The Blue Crown brand was marketed as a premium product, easily identified under the hood of a hot rod by the blue ring near the top of the porcelain on the plug.

Blue Crown Spark Plugs
Kyle Smith

World War II meant many companies relied on defense contracts, and during that time Blue Crown was producing 40,000 spark plus per day. Both before and after the war though, Blue Crown was known for the company’s racing efforts, sponsoring cars in races far and wide but most notably Offenhauser-powered single-seaters in the Indianapolis 500.

A team of two cars for the 1947 and ’48 seasons was upped to three for 1949 following two victories by Mauri Rose behind the wheel of a Blue Crown Special. Driver and teammate Bill Holland would win the 1949 race, with Rose falling victim to mechanical failure in the final laps, while team newbie George Conner came in third. Part of the race strategy during these runs was to make just one (one!) pit stop over the course of the grueling race. That meant carrying fuel loads that some truck drivers wouldn’t consider these days, let alone race car drivers.

1949 Lesovsky-Offenhauser Indianapolis Blue Crown Special
RM Sotheby’s
1949 Lesovsky-Offenhauser Indianapolis Blue Crown Special
RM Sotheby’s

1949 Lesovsky-Offenhauser Indianapolis Blue Crown Special
RM Sotheby’s

The brand continued to sponsor cars entered in various types of racing through the mid-1950s. The Indy cars bearing the Blue Crown name are the most popular and sought after, though there were drag racers, dirt track cars, and NASCAR racers that carried the name.

Of course, my humble Model A shares exactly nil with the three consecutive Indy winners which wore the Blue Crown brand on the side, other than the use of these snazzy spark plugs. They are such neat pieces I intend to pull them from my Model A and put them on display in my basement since they’re such interesting conversation pieces.

I’ll install a correct set of Champion plugs to fill the holes in the cylinder head and keep the 200-cube four puttering along nicely, though it might sadden me a little to think I am breaking such an interesting tie between my little black coupe and those bright, proud racers.

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    Would like to know about the Blue Crown spark plug connection with a plant in Defiance, Ohio, with some race car fabrication possibly also occurring there. Circa later 1940’s.

    My dad was a used car mechanic back some 50 years ago. After cleaning his office I ran across about 100 blue crown mt14x spark plugs. I’ve never heard of them before the find. My question is what did this specific spark plug fit back then? He didnt have a single seat race car.

    Unfortunately I don’t have a part number application or cross reference chart for vintage Blue Crown plugs. It might be worth asking on the HAMB message boards ( as there is a lot of folks with generational knowledge there who might either know off hand or be better prepared to point you to a specific fit for that part number

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