Well I came up with the The number of turns head thread Test.
Basically there is a seat in the head for the wider portion of the plugs just above the threads to stop on. This seat, notch, ledge, whatever... read more

Mustang FeedsIHRA acquires Empire Dragway. It has announced upgrades, expanded events, and a long-term investment in Northeast drag racing facilities.
Sean Bellemeur added another big line to his racing resume at zMax. Bellemeur recorded his 50th NHRA national event win.
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Factory Stock made its return to the NHRA this weekend. Jonathan Allegrucci brought home the NHRA 4-Wide Nationals win.
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The NHRA Pro Mod racers went four-wide racing at zMAx Dragway. Here's a recap of all the action from the NHRA 4-Wide Nationals
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The NHRA visited zMax Dragway for the 4-Wide Nationals. Here's a recap of all the action for this weekend's NHRA national event.
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Nitro Funny Car clutch tuning is super complex. In this episode of Tech Inspection we learn about clutch tuning from Tim Fabrisi.
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