Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
6.7 Cummins Head Studs
Aftermarket 12-point head studs for the Dodge/Ram 6.7L Cummins diesel straight-six engine, manufactured by TorqBolt in MP35N (260 ksi) and Custom 465 (220 ksi H950) alloys. Each stud cap face carries the struck tB ligature plus the alloy grade marking (MP35N or specified).
High-boost diesel rebuilds and work-truck performance upgrades commonly replace the factory head bolts with aftermarket head studs to handle higher peak cylinder pressures (often 200+ bar) without head-gasket lift. Head studs deliver more accurate clamping load than torque-to-yield head bolts and allow easy head removal between rebuilds.
Why head studs over factory head bolts
- More accurate clamping load (preload measured by stretch, not torque-yield)
- Easier head removal between rebuilds (head lifts off studs, studs stay in block)
- Higher tensile capability than factory torque-to-yield bolt material
- Reusable across multiple service cycles
Alloys
| Alloy | Tensile | Use case |
|---|---|---|
| MP35N (UNS R30035) | 260 ksi | extreme-boost performance |
| Custom 465 H950 | 220 ksi | standard high-performance |
| AISI 8740 chromoly HT | up to 220 ksi | cost-conscious upgrade |
Frequently asked questions
What is a 12-point bolt?
A 12-point bolt has 12 splines arranged every 30 degrees on the OUTSIDE of the bolt head, also called a bi-hex or double-hex bolt. The 12 external splines provide twice the wrench-engagement angles of a standard hex head, allowing higher applied torque before cam-off, which is why aerospace and motorsport applications adopt the geometry.
Are 12-point bolts the same as ISO 14579?
No. ISO 14579 specifies an INTERNAL hexalobular socket head (similar to Torx) recessed inside a cap screw. External 12-point bolts under MS21250 / NAS1351 / AS3216 use an EXTERNAL bi-hex head driven by a 12-point socket wrench. Both involve 12 features but on different sides of the bolt head and require different drivers.
Which alloys does TorqBolt manufacture 12-point bolts in?
TorqBolt produces 12-point bolts in A286 (UNS S66286), Inconel 718 (UNS N07718), Ti-6Al-4V Grade 5, MP35N (UNS R30035), Custom 465 H1025, AISI 8740 chromoly heat-treated, AISI 4340, 17-4 PH, H-11 tool steel, and L19 race-grade alloy steel. Choice depends on tensile target, service temperature, and corrosion environment.
Is TorqBolt AS9100D certified?
Yes. TorqBolt operates under AS9100D Rev D and ISO 9001:2015 quality management systems, audited annually by the registrar. NORSOK M-630 and NACE MR0175 / ISO 15156 qualifications cover offshore and sour-service applications. Mill test reports MTC 3.1 standard and MTC 3.2 critical-service witness are issued with every lot.
What lead time should I expect?
Stock alloys (A286, AISI 8740, AISI 4340, 17-4 PH, 316 stainless) ship in 4 to 6 weeks. Specialty alloys (Inconel 718, MP35N, Custom 465, Ti-6Al-4V, L19) ship in 8 to 12 weeks depending on raw-bar lead time at the alloy producer. Critical-service orders requiring third-party witness inspection (MTC 3.2) add 1 to 2 weeks for witness scheduling.
Why 6.7 Cummins head studs are mandatory at 60+ psi
The Dodge / Ram 6.7L Cummins diesel uses 26 M14 head bolts in TTY configuration on a closed-deck iron block. The 6.7 inline-six generates more cylinder pressure per liter than any V8 of the same generation, so the head clamp matters even more. Factory 18 to 22 psi handles fine on stock bolts; at 50+ psi (compound-turbo or single-turbo upgrade builds) the stock bolts cannot maintain clamp. MP35N head studs at 260 ksi are the standard upgrade for 60-80 psi street/competition builds.
Engine-Specific Installation Notes
Diesel head stud retrofits in high-boost applications (35 psi+ on Ford 6.0L Powerstroke, 50 psi+ on 6.7L Cummins, 30 psi+ on Duramax) require careful sequencing. Common practice:
- Remove factory head bolts in reverse of the factory torque sequence to avoid warping the head.
- Chase all threaded holes in the block and remove any debris with compressed air.
- Install studs hand-tight, then back off 1 turn so the stud free-floats during head installation. The head sets the stud position, not the operator.
- Install head and stud nuts. Lubricate threads and under-nut washer face with the manufacturer-specified lubricant (typically moly + oil mix).
- Tighten in 3 stages following the factory torque pattern: stage 1 to 30 ft-lb, stage 2 to 60 ft-lb, stage 3 to final torque (typically 110 to 130 ft-lb depending on engine).
- For higher-boost retrofits, manufacturer may specify a 4th step: turn the nuts an additional 90 degrees from final torque (torque-angle method).
- Re-torque after first heat cycle (run engine to operating temperature, allow to cool overnight, re-check torque) to recover any lost preload.
Always follow the bolt manufacturer's torque spec, not the factory bolt spec. Aftermarket studs in higher-strength alloys (MP35N at 260 ksi) take significantly higher final torque than factory bolts (8740 at 150 to 180 ksi).
Request a Quote
Specify Dodge/Ram 6.7L Cummins application + alloy preference + bolt circle measurement. RFQ to info@torqbolt.com, call +91-22-66157017.
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