Product Description:
Hawks Motorsports is pleased to offer our clients the following SBC ARP Stainless Steel 12-Point Header Bolts, 3/8"-16, Set of 12, ARP (400-1201). This 12-piece header bolt kit is designed for Chevrolet Small Block applications and features 3/8"-16 threads, a 0.750-inch underhead length, 12-point heads, and polished stainless steel construction. ARP specifies the bolts at 180,000 psi tensile strength, and washers are included.
For a gearhead building a clean Small Block Chevy, header hardware is one of those little details that can make a big difference once the engine bay starts coming together. The compact 12-point heads give you better socket access around those tight header tubes and flange areas, while the polished stainless finish adds the kind of clean, finished look that stands out when you're leaning over the fender admiring the build. Whether you're bolting headers onto a weekend cruiser, a street/strip SBC, or finishing up a full engine restoration, the right fasteners are part of getting the whole combination dialed in.
The ARP 400-1201 kit uses 3/8"-16 threads and 0.750-inch underhead-length bolts with a 3/8-inch wrench head size. The polished stainless construction is suited to the heat and corrosive environment associated with exhaust header installations.
This kit is specifically cataloged for Chevrolet Small Block applications. It should not be confused with ARP's LS-series header hardware, which uses different M8 applications and part numbers.
KEY FEATURES
- SKU: 400-1201
- Brand: ARP
- Chevrolet Small Block header bolt kit
- 12-point head design
- 3/8"-16 thread
- 0.750" underhead length
- Polished stainless steel construction
- Set of 12 bolts
- Washers included
- 3/8" wrench head size
- ARP-rated 180,000 psi tensile strength
- Compact head design for improved socket access around header tubes
- Intended for exhaust header installation on Chevrolet Small Block applications
PRODUCT SPECIFICATIONS
| Specification | Details |
|---|---|
| Brand | ARP |
| Part Number | 400-1201 |
| Product Type | Header Bolt Kit |
| Application | Chevrolet Small Block |
| Fastener Style | Bolt |
| Head Style | 12-Point |
| Thread Size | 3/8"-16 |
| Underhead Length | 0.750" / 19.0 mm |
| Material | ARP Stainless Steel |
| Finish | Polished |
| Quantity | 12 |
| Wrench Head Size | 3/8" |
| Washers | Included |
| Tensile Strength | 180,000 psi |
ARP's current product page and 2026 catalog confirm the core specifications above.
VEHICLE FITMENT / FITS THE FOLLOWING MODELS
Chevrolet Small Block Applications
The 400-1201 is an engine-application header bolt kit, rather than a vehicle-specific fastener. ARP identifies it for Chevrolet Small Block applications.
Applicable Small Block Chevrolet engine families may include:
- 262 CID
- 265 CID
- 267 CID
- 283 CID
- 305 CID
- 307 CID
- 327 CID
- 350 CID
- 400 CID
Important: Exact vehicle fitment depends on the cylinder heads, header flange design, and header being used. Verify the header application and required fastener length before ordering.
IMPORTANT APPLICATION NOTES AND EXCLUSIONS
- Designed for Chevrolet Small Block header applications.
- Uses 3/8"-16 threads.
- Uses 0.750" underhead-length bolts.
- Sold as a set of 12.
- Polished stainless steel construction.
- 12-point head requires an appropriate 12-point socket.
- Washers are included.
- This is not an LS-series header bolt kit. ARP catalogs LS header hardware separately using M8 fasteners.
- Do not substitute based solely on engine family or vehicle generation.
- Verify header flange thickness and required bolt length for the specific header and cylinder-head combination.
INSTALLATION NOTES
- Verify the header and cylinder-head application before installation.
- Confirm the cylinder-head threads are compatible with the 3/8"-16 fasteners.
- Verify the 0.750" underhead length provides adequate thread engagement without bottoming out.
- Use the supplied washers as intended.
- Use the appropriate 12-point socket for installation.
- Follow the header manufacturer's installation instructions and ARP's current torque recommendations.
- Inspect threads and mating surfaces before installation.
- Check header clearance around the bolt heads before final tightening.
- Recheck the installation after the engine has been heat-cycled as appropriate for the header manufacturer's instructions.
FREQUENTLY ASKED QUESTIONS
What is ARP 400-1201?
ARP 400-1201 is a 12-point stainless steel header bolt kit for Chevrolet Small Block applications.
How many bolts are included?
The kit contains 12 bolts. Washers are also included.
What size are the bolts?
The bolts use 3/8"-16 threads and have a 0.750" underhead length.
What material are the bolts made from?
The 400-1201 uses ARP stainless steel with a polished finish.
What size socket does the bolt use?
The ARP application information identifies a 3/8-inch wrench head size for this bolt.
Are washers included?
Yes. ARP's current catalog notes that bolts come with washers.
Is this kit for LS engines?
No. The 400-1201 is cataloged for Chevrolet Small Block applications. ARP lists separate M8 header hardware for LS-series engines.
How does 400-1201 differ from ARP 100-1201?
Both are Chevrolet Small Block 12-point header bolt kits using 3/8"-16 threads and 0.750" underhead length. The 400-1201 is the polished stainless version, while the 100-1201 is the black oxide version.
