Advantages of head studs
Chris
Also, in an aluminum block with aluminum threads, the chances of galling a thread are high, the more times you R&R heads. Rule of thumb is no more than 4 times, so I've heard ...
I read somewhere that engineers use studs and accountants choose bolts.
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...I would bet the ARP studs are made from exactly the same material as the bolts.The only benefit I can see is for multiple head swaps. You can lock the studs into the aluminum block with Loctite (much better to have a bonded threaded assembly). Then when you torque/loosen/retorque ...all of this is done between the stud and nut which are both high tensile steel.
...probably also gives a better torque/tension relationship which will result in more consistant clamp loads across the head.
Ps. I am a Loctite Engineer so nuts and bolts are my bread and butter!
If everything is right, the stud should be installed finger tight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. Remember, an undercut shorter stud will have a rate similar to a longer, standard shank stud. This provides a more even clamping force on the head. Because the head gasket will compress upon initial torquing, make sure studs and bolts are re-torqued after the engine has been run
This twisting force has to be added into the total force applied to the fastener.
I use red loctite on head studs and install them finger tight. Smokey Yunick and Carrol Smith do (did) as well.





