To overcome head gasket failures that can occur in diesel engines employed in truck and RV applications, industry leader ARP has introduced extra heavy-duty head studs for the popular Ford, Dodge and GM powerplants. These ARP studs are rated at 220,000 psi tensile strength, and provide the clamping force required to keep cylinder heads from lifting due to higher combustion pressures. The studs are manufactured in ARP's Santa Paula, CA plant from proprietary ARP 2000 material, with threads rolled after heat-treat to provide optimum fatigue strength. They are centerless ground to assure perfect concentricity. The ends of the studs are broached to facilitate easy installation. This feature also enables the cylinder head to be removed in tight quarters. Also included in each kit are heat-treated, chrome-moly steel 12-point nuts and parallel-ground washers. They are black oxide finished for extra durability.
INSTALLATION METHOD FOR CUSTOM AGE 625 HEAD STUD KITS
Part Number: 247-4207 Application: Cummins 3.9L (4BT) Diesel
Note: This kit requires modification to the rocker arm pedestal to accommodate a shorter rocker arm
pedestal head stud included in this kit (see illustration A on reverse side). These changes were
designed to bring our 12pt nut and washer combination down to the same installed height as the
factory head bolt due to clearance issues with the valve cover. We have also included secondary 8mm
rocker arm pedestal (hold down) bolts that were previously not available.
Always verify the part number for your application with the part number on the side of box and the
part number on the instruction sheet. This will help ensure you have the correct installation
procedure for your specific application before installing any components.
To ensure proper thread engagement and accurate torque readings, clean ALL threads in the block and the
threads in the cylinder head that secure the rocker arm pedestal to the head. Chase if necessary with ARP
Thread Chaser(s), part numbers 912-0008 (M12 x 1.75) and 912-0001 (M8 x 1.25).
Clean and inspect all hardware prior to installation. Look for obvious defects or shipping damages, plus
proper fit, length and dimension (see illustration B on reverse side).
If the cylinder head studs protrude into a water jacket, lubricate the block threads of the studs with ARP
Screw studs into the block “HAND TIGHT ONLY”. NOTE: LOCTITE MAY BE USED IF PERMANENT
MOUNTING OF THE STUD IS PREFERRED.
Install the cylinder head and check for binding or misalignment.
Install the pushrods.
Install the rocker arms and the rocker arm pedestals onto the cylinder head as an assembly according to
OEM procedures. Make sure the dowel on the bottom of each pedestal is aligned properly with the
alignment holes in the cylinder head and the pedestals are sitting down flush on the head with the valve lash
adjusters completely backed off.
Lubricate the stud threads, nuts and washers with ARP ULTRA-TORQUE FASTENER ASSEMBLY
LUBRICANT. ARP recommends using the ARP ULTRA-TORQUE FASTENER ASSEMBLY
LUBRICANT that is provided with each kit as opposed to motor oil. This is due to higher friction on
the studs as well as inconsistencies in the clamping force of the fasteners when motor oil (or low
quality lubricant) is used. Also apply ARP Ultra-Torque Assembly Lubricant to the threads on the
secondary 8mm rocker arm pedestal (hold down) bolts.
Install the washers and the 12pt nuts onto the cylinder head studs and tighten them hand tight.
Install the secondary 8mm rocker arm pedestal (hold down) bolts into the cylinder head. Tighten the bolts
hand tight. Note: The secondary 8mm rocker arm pedestal (hold down) bolts must be installed in
place before tightening the head studs to properly align the tips of the rocker arms with the valve
PRELOAD (TORQUE) RECOMMENDATIONS
Following the manufacturers recommended torque sequence tighten the nuts in three equal steps
to the specifications listed below with ARP ULTRA-TORQUE FASTENER ASSEMBLY LUBRICANT.
M12 studs 150 ft lbs M8 bolts 25 ft lbs
Note: ARP Ultra-Torque Fastener Assembly Lubricant has been specifically designed to reduce tension
preload scatter and eliminate the need to cycle high performance engine fasteners before final installation.
ARP Ultra-Torque far surpasses all requirements offered by previous ARP lubricants in terms of fastener
preload repeatability and performance lubricating properties. For more information on ARP Ultra-Torque visit
our website at www.arp-bolts.com or call 1 800-826-3045.