ARP Engine Head Stud Kit

If you are pulling your cylinder heads to do head gaskets, this ARP head stud kit is the upgrade we recommend for the Rover 3.9L to 4.6L V8 with 10 bolt heads. It replaces the factory torque to yield stretch bolts, which are designed to be used once and are not meant to be reused. The ARP studs are made from ARP2000 material rated at 220,000 PSI tensile strength, with a black oxide finish, hardened washers, and 12 point nuts included in the kit. Because a stud threads into the block and stays put while you torque the nut on top, it delivers a far more consistent and repeatable clamping load than a stretch bolt, which means a more even seal across the head gasket and hardware you can reuse if the heads ever come off again.

Here is where our advice differs from the printed instructions, and we want to be upfront about it. ARP packages this kit with a torque procedure of three passes at 30, 60, and a final 100 foot pounds. In our own shop experience with these aging Rover V8 engines, we recommend a gentler sequence of three passes at 20, 40, and a final 80 foot pounds, followed in the same order as the factory bolt sequence. The reasoning is simple. These aluminum blocks are decades old now, and the threads in the block are not as fresh as they were when the engine left the factory. Pull those threads too hard and a stud can strip its seat in the block. Once that happens you are into a thread repair such as a helicoil to save the block, and only then would you be able to safely reach the higher 100 foot pound figure. Our 80 foot pound final pass is the number we trust to give you a reliable clamp load on a high mileage engine while protecting those original block threads. In metric terms that final pass is roughly 108 Nm (80 foot pounds) versus the ARP figure of about 136 Nm (100 foot pounds). This is our recommendation based on years of building these engines, and we stand behind it. ARP's printed specification remains available in the box for anyone who prefers to follow the manufacturer to the letter.

A few practical notes for a clean install. Clean the threads in the block and chase them if needed so your torque readings are accurate, make sure the head and washer mating surfaces are free of oil and debris, and use the assembly lubricant on the nut threads and under the nuts as the instructions describe. Bring the nuts up in the recommended sequence over your three passes rather than tightening any one stud all the way in a single go.

Fits:
Range Rover Classic (1990 to 1995) 3.9 liter and 4.2 liter Rover V8 Petrol/Gas
Range Rover P38 (1995 to 2002) 4.0 liter and 4.6 liter Rover V8 Petrol/Gas
Discovery I (1994 to 1999) 3.9 liter and 4.0 liter Rover V8 Petrol/Gas
Discovery II (1999 to 2004) 4.0 liter and 4.6 liter Rover V8 Petrol/Gas
Defender 90 (1993 to 1997) 3.9 liter and 4.0 liter Rover V8 Petrol/Gas

Part Number: ARPSK
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