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    Head Studs

    Head Studs, TorqBolt 12-point fastener with tB ligature and alloy grade marking

    Head studs are two-piece engine fasteners (a threaded stud plus a 12-point nut) that replace stock cylinder-head bolts on heavy-duty diesel rebuilds, high-boost gasoline engines, and rebuild-heavy race builds. The two-piece design is widely used because the stud stays planted in the block during head removal, so the head deck only sees axial preload from torque on the nut, not the combined torque-plus-twist a one-piece bolt would impose, which gives more repeatable, more accurate preload across multiple rebuild cycles. The 12-point nut is also very popular because head-stud preload typically runs 200-260 ksi and the twelve splines deliver the higher applied torque needed for that preload without camming the wrench off the joint.

    TorqBolt manufactures head studs in MP35N (UNS R30035, 260 ksi for top-end race and sour-service), Custom 465 (260 ksi corrosion-resistant), AISI 8740 chromoly heat-treated (220 ksi for heavy-duty diesel), AISI 4340, 17-4 PH H1025 and L19 race-grade alloy steel to AS9100D Rev D and ISO 9001:2015 quality systems. Each stud and nut carries the struck tB manufacturer ligature plus the alloy grade marking, and every lot ships with a mill test report (MTC 3.1 standard, MTC 3.2 critical with hardness, tensile, magnetic-particle and rolled-thread-after-heat-treatment process inspection records).

    Materials

    Alloy choice is set by the spec, the service temperature, the corrosion environment, and the strength target. TorqBolt routinely produces head studs in A286 (UNS S66286), Inconel 718, Ti-6Al-4V (Grade 5), MP35N (UNS R30035), Custom 465 stainless, AISI 8740 chromoly heat-treated, AISI 4340, 17-4 PH H1025 condition, H-11 tool steel, and L19 race-grade alloy steel.

    Head stud product family overview

    A head stud is a threaded rod that screws into the engine block deck and extends upward through the cylinder head; a 12-point nut on top sets the clamping force. The advantage versus head bolts: the head sets the stud position before the nut is torqued, improving head-gasket seating accuracy and allowing precise stretch measurement. For high-boost diesel and race-engine builds, head studs are mandatory above ~30 psi peak boost.

    Engine-platform head stud kits

    TorqBolt produces 12-point head studs in MP35N, Custom 465 and 8740 chromoly for the most-rebuilt boost and race platforms. Engine-specific bore-pattern, stud length, and nut-thread fitment guides on each platform page:

    Diesel-truck head stud kits

    Gasoline race / motorsport head stud kits

    Request a Quote

    RFQ to info@torqbolt.com, call +91-22-66157017, or WhatsApp +91-22-66157017. Mill test report (MTC 3.1 standard, 3.2 critical-service) ships with every lot.

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