Autolite spark plug with callout labels for seat, unthreaded sha…

Annotated studio photo of a single Autolite spark plug standing upright against a white background, showing the white ribbed ceramic insulator, hex, tapered seat and threaded shell with a hooked ground electrode. Hand-added callout labels point to "Plug seals here," the unthreaded shank ("No place here for crud / thread blowby to accumulate") and "Threads to hold the plug into the head," with a note comparing it to an NGK that was threaded over that whole area.

AI caption February 2016 · Photo 258 of 409