This is the standard 12-point head flywheel bolt for the Ford 1600 Kent engine. The flywheel bolts are subjected to some incredible stresses in FF1600 racing engines, even when everything is working perfectly. They should be replaced at every engine rebuild or any time the flywheel is removed.
New bolts should be installed with Loctite 271 (Red) High-Strength Threadlocker (Part No. LT-27121, sold separately) and torqued to 55 lb-ft. Sold individually; 6 required.
3/8-24 UNF (SAE) thread fits Ford 711 (crossflow) and 771 (Fiesta) crankshafts as well as aftermarket copies from FFI and SCAT. The 0.90" under-head length (1/4" unthreaded) is designed to fit the original Ford flywheel and dimensionally-identical copies (such as the aftermarket JAE FF1600 flywheel).