ARP Head Studs to suit Toyota 1HZ/1HD-T Engines
Please note: This is the standard 11mm direct-replacement kit. Do NOT use the factory Toyota factory torque-to-yield bolt tightening procedure or torque angles when installing this kit. You must follow the specialized ARP torque sequence and specifications provided in the box. It is absolutely critical to use the included ARP Ultra-Torque Fastener Assembly Lubricant underneath all nuts and washers during installation to prevent thread galling and ensure an accurate torque reading. For extreme high-boost race applications exceeding 35+ psi, a larger 13mm structural kit is available but requires professional block drilling and tapping (enquire about part # HSKTO340).
Genuine ARP Pro Series 11mm Cylinder Head Stud Kit. Protect your high-boost or heavy-towing Toyota 4.2L diesel against catastrophic head gasket failure with the ultimate valvetrain and block fastening solution. Specifically engineered to suit Toyota 1HZ, 1HZ-T, and 1HD-T engines, the ARP-1HZ kit replaces elastic factory head bolts with ultra-high-tensile studs forged from premium ARP2000 alloy. By eliminating the twisting forces created when tightening standard bolts, these studs deliver a remarkably even, concentric torque distribution across the entire mating surface—boosting clamping pressure by up to 40% over original equipment. This kit is a direct drop-in upgrade that requires no modification to your block or head bolt channels. Whether you are running an aggressive aftermarket turbo upgrade on a 1HZ or refreshing a high-kilometer 1HD-T 80 Series, investing in an authentic ARP stud kit delivers the professional-grade reliability your Land Cruiser needs to endure the harshest conditions.
Includes:
26x ARP2000 High-Tensile 11mm Head Studs
26x Hardened Parallel-Ground Washers
26x 12-Point Chromoly Steel Locking Nuts
1x 0.5 oz. Pack of ARP Ultra-Torque Assembly Lubricant
1x Official ARP Torque Specification Sheet
Details:
- Manufactured from premium ARP2000 alloy rated at 220,000 psi tensile strength
- Delivers up to 40% greater clamping force over factory torque-to-yield (TTY) bolts
- Eliminates thread-twisting friction for a completely even cylinder head load distribution
- Direct drop-in fitment requiring no block machining or drilling modifications
Technical Specifications:
- Supplier SKU: ARP-1HZ / HSKTO340A
- Thread Diameter: 11.0mm (Factory Standard)
- Material Composition: Forged ARP2000 Alloy
- Nut Engagement Profile: 12-Point Hex Head
- Compatibility: Toyota 1HZ, 1HZ-T & 1HD-T (12-Valve 4.2L SOHC Diesel Engines)
