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Early Spark Plug Reference Chart?


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I've seen mentioned for a 1910 model 10. Originally used the AC-1 plug.( take a part)

Known then in the trade as " the Buick plug"

7/8 thread

1-1/8 hex

"Long plug with the 1/2" reach"


Later on an improved "Titan" (one piece design plug over the earler 2 piece crappy leaky one )used in 1915-25 Buicks were AC 78 long or 78LT


Today a common replacement is the Autolite 3076 or 3077( 3077 a step hotter)


Champion W18 , W89, 518 have worked o.k for some (I've read)


You can find cross referances between these common plugs an go from there


Learning the meaning of numbering /letter system for each is helpfull for heat and reach etc.

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Very funny!  I avoided the 3x as it is sooo closely associated with the model "A " anyone who knows old cars upon seeing them in a 09 Buick will say " Oh! He has Model A plugs in there" 😝

 They would give the best overall appearance in such an early machine.

Note:I believe if running just a mag in that old Buick the plug gap would be far smaller then the Model A ford specs.of .032 -.035 range..

..025 (possibly less) has been mentioned or written about in old manuals..


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Champion 1-Com might be a good choice. You can find NOS ones on eBay occasionally. They came with both style wire clips. The early ones are take apart, the later ones are single piece. I use them in my ‘23 Studebaker



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