Use to locate TDC, whistles on the compression stroke

Next time you are needing to locate Top Dead Center on your hot rod's engine, let Mr. Gasket lend a hand. Our TDC indicator threads into 14mm or 18mm threaded spark plug holes. It whistles on the compression stroke and stops whistling at approximately Top Dead Center. Just a few of the many examples of when needed are, timing chain inspection or replacement, distributor installation and cylinder leak down.