Stretched Head bolts can lead to blown head gaskets and overheated engines. Head Studs offer a alternative when its time to reseal a engine head. Bolts when torqued are affected by two difference forces. The bolt stretches and twists. A Headstud will not twist as only the nut is torqued down. This allows them to add more clamping force and helps reduce the chance of burning up a gasket. Fit 55-00 Chevy Small Block SBC 265 267 283 302 305 307 327 350 383 400.