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Stage 8 Locking Header Bolts That Keep Dodge HEMI Headers From Backing Out
The BK111 is a complete Stage 8 locking header bolt kit for Dodge HEMI engines, including the 5.7L, 6.1L, and 6.2L variants, using M8 by 1.25 by 25mm fasteners with the Stage 8 locking hardware system that mechanically prevents the bolts from backing out under the vibration and thermal cycling of performance exhaust use. Header bolts are among the most commonly neglected fasteners on high performance exhaust systems, and on HEMI engines the combination of high operating temperatures, engine vibration, and the thermal expansion and contraction of stainless steel headers creates exactly the conditions that cause standard bolts to loosen over time.
Stage 8 locking hardware addresses this with a positive mechanical lock that does not rely on thread locking compound, spring tension, or torque alone to stay tight. The BK111 kit provides the correct fastener specification for HEMI header applications in a complete set that covers both cylinder heads. Using the right bolt length and thread pitch is critical on the HEMI head because an incorrect fastener can bottom out before clamping, leading to leaks even after a fresh installation. This bolt kit takes the guesswork out of fastener selection and delivers a solution from Kooks that is tested and proven on the same HEMI platform their headers are built for.
Key Features
- Stage 8 positive mechanical locking system prevents bolt back out
- Correct M8 by 1.25 by 25mm specification for Dodge HEMI 5.7L, 6.1L, and 6.2L cylinder heads
- Complete kit covers both cylinder banks
- No thread locker or special tools required for the locking mechanism
- Resistant to loosening under exhaust system vibration and thermal cycling
- Designed for use with Kooks HEMI long tube headers
What's Included
- Stage 8 locking header bolts (M8 by 1.25 by 25mm), quantity as required for complete HEMI installation
- Stage 8 locking retainer clips for each bolt
Specifications
| Specification | Detail |
|---|---|
| Part Number (MPN) | BK111 |
| UPC | Contact us for UPC |
| Bolt Size | M8 by 1.25 by 25mm |
| Locking System | Stage 8 Positive Mechanical Lock |
| Application | Dodge HEMI 5.7L, 6.1L, 6.2L Engines |
| Use With | Kooks HEMI Long Tube Headers |
| Fitment | Dodge/Chrysler HEMI V8 Applications |
Frequently Asked Questions
What engines does this bolt kit fit?
This bolt kit is designed for Dodge HEMI engines, specifically the 5.7L, 6.1L, and 6.2L variants used in Challenger, Charger, 300, and other Chrysler platform vehicles.
What is Stage 8 locking hardware?
Stage 8 is a brand and system of positive mechanical locking fasteners. Each bolt uses a retainer clip that locks into a groove on the bolt head and a fixed point on the header flange or adjacent hardware, preventing the bolt from rotating and loosening without mechanically defeating the lock. It is one of the most reliable anti loosening systems for high vibration, high temperature exhaust applications.
Why do header bolts loosen on HEMI engines?
The HEMI produces significant thermal cycling across the cylinder head and header flange interface due to its high operating temperatures. Combined with engine vibration, this cycling causes standard bolts to slowly back out over time, resulting in exhaust leaks at the header flange.
Can I use this bolt kit bolts with a thread locking compound?
Thread locking compounds are not necessary with Stage 8 locking hardware and would be counterproductive since the locking retainer is the primary anti loosening mechanism. Standard installation follows the Stage 8 procedure with the retainer clips.
What is the bolt length of this bolt kit?
The bolts are 25mm in length with an M8 by 1.25 thread pitch, which is the correct specification for the HEMI cylinder head exhaust port bolt pattern used with Kooks headers.
Do I need to re torque this bolt kit bolts after a heat cycle?
Stage 8 locking hardware maintains its clamping force more consistently than standard bolts across heat cycles. However, inspecting fastener tightness after the first heat cycle is always good practice with any header installation.
Can I use this bolt kit with headers from other manufacturers?
This bolt kit uses the M8 by 1.25 by 25mm specification that matches Kooks HEMI header flange holes. Compatibility with headers from other brands depends on their flange bolt hole size and clearance for the Stage 8 locking hardware. Verify before ordering.
Are the Stage 8 retainer clips reusable?
Stage 8 locking hardware is generally designed to be reusable. When removing headers, carefully retain the locking clips for reinstallation or replace them with fresh hardware.
Is this bolt kit the same as the BK110?
No. The BK110 is designed for GM LS engines and includes 12 pieces. This bolt kit is designed for Dodge HEMI applications with the fastener specification matching that engine's cylinder head.
Does this bolt kit come with installation instructions?
Stage 8 locking hardware includes instructions for proper installation of the retainer clips. Follow those instructions for the correct installation procedure.
Installation Instructions
- Clean the HEMI cylinder head exhaust port flange bolt holes and remove any old thread locking compound.
- Install new header gaskets on the cylinder head surface.
- Position the Kooks HEMI headers against the cylinder head with gaskets in place.
- Thread this bolt kit M8 by 1.25 by 25mm bolts by hand into the cylinder head bolt holes through the header flange.
- Torque all bolts to the specification in the Kooks header installation instructions in a crossing pattern.
- Install the Stage 8 locking retainer clips onto each bolt head, securing the clip to the header flange or adjacent fixed point per Stage 8 instructions.
- Inspect all retainer clips to confirm they are fully engaged before starting the engine.
- Check bolt tightness after the first heat cycle and re torque if necessary, then reinstall retainer clips.
Prop 65 Warning
WARNING: This product can expose you to chemicals known to the State of California to cause cancer, birth defects or reproductive harm. For more information go to www.P65Warnings.ca.gov.
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