Studs: Why are they better?

Thunderkyss

Veteran Member
Sep 16, 2012
223
Texas
Particularly for heads, why are studs better than head bolts, if the bolts go into the block as far as the studs do?
 

stroked383

Veteran Member
Lifetime Gold Member
Jul 18, 2011
764
Saugerties, NY
Studs clamp better then bolts. The bolts twist and stretch as they get torqued where as the studs do not. There is some info at arp-bolts.com
http://arp-bolts.com/pages/technical_design.shtml
Edit: from ARP website : 2.
Q. Do I need head bolts or studs for my engine?

A. This depends on the installation. On many street-driven vehicles, where the master cylinders and other items protrude into the engine compartment, it’s probably necessary to use head bolts so that the cylinder heads can be removed with the engine in the car. For most applications, however, studs are recommended. Using studs will make it much easier to assemble an engine with the cylinder head and gasket assured of proper alignment. Studs also provide more accurate and consistent torque loading.
 
Last edited:

hhott71

R.I.P 11/19/18
Lifetime Gold Member
Mar 30, 2001
14,377
Joplin Mo. 64801
SBC or BBC don't need head studs because they have at least 5 bolts around a cylinder to provide clamping force.
A N/A engine should never need them.
Most mild blown or no2 won't either.
When you start pushing the limits, studs are advisable in any application.
 

Thunderkyss

Veteran Member
Sep 16, 2012
223
Texas
hhott71 said:
SBC or BBC don't need head studs because they have at least 5 bolts around a cylinder to provide clamping force.
A N/A engine should never need them.
Most mild blown or no2 won't either.
When you start pushing the limits, studs are advisable in any application.

Thanks. But the question was what's the difference? What makes a stud "stronger" If they are made of the same material, go the same depth, what difference does it make?
 

Bikefixr

Veteran Member
Lifetime Gold Member
Mar 13, 2006
1,881
Any force on the bolt goes in two directions--vertically from the bolt being tightened into the block and in a twisting motion from the top of the bolt being twisted into the top of the block. Since studs use two different parts, the force is distributed between them, thus reducing it on both of them.

Also, studs have the threads rolled into the shank, this compresses the metal and keeps the grain of the metal in tact. Bolts usually have threads cut into them, removing metal and cutting through the grain.

Studs often have more thread engagement because they are screwed all the way down whereas a bolt is usually shorter than the hole it is screwed into.

Studs pose less wear and fatigue to the threads. they go in finger-tight one time whereas bots go in and out as often as needed, and as you torque the bolt down, it causes a lot of wear to the threads as the bolt pulls up into the thread grooves.

Studs ease assembly on some engines. I always use them on the main caps.

Studs of a given strength are less $ than a bolt. You can get cold-rolled forged bolts of very high strength, but they cost more than the studs will.
 

dubs74camaro

Veteran Member
Mar 19, 2011
707
Big Block, OR
The fastern will not start to stretch until it runs into resistance. The bolt will run into it at the top and bottom. The stud will have a better "stretching" effect rather than twisting. However, even just going with an ARP 12 pt head bolt is a nice upgrade over stock. I like the bolt and washer combo over the washer being built into the head like a stock bolt.
 

OneShoe50

Member
Dec 28, 2009
94
Albuquerque, NM
And, most head bolts are "torque to yield", reduced shank and are not reusable. After a bolt is torqued close to the end of its elastic limit to where it won't spring back after removal. Studs are reusable and provide a better distribution load, as mentioned above.
 

nonstopgo68

Veteran Member
Apr 19, 2011
875
Mobile, Alabama
Bikefixr said:
Any force on the bolt goes in two directions--vertically from the bolt being tightened into the block and in a twisting motion from the top of the bolt being twisted into the top of the block. Since studs use two different parts, the force is distributed between them, thus reducing it on both of them.

Also, studs have the threads rolled into the shank, this compresses the metal and keeps the grain of the metal in tact. Bolts usually have threads cut into them, removing metal and cutting through the grain.

Studs often have more thread engagement because they are screwed all the way down whereas a bolt is usually shorter than the hole it is screwed into.

Studs pose less wear and fatigue to the threads. they go in finger-tight one time whereas bots go in and out as often as needed, and as you torque the bolt down, it causes a lot of wear to the threads as the bolt pulls up into the thread grooves.

Studs ease assembly on some engines. I always use them on the main caps.

Studs of a given strength are less $ than a bolt. You can get cold-rolled forged bolts of very high strength, but they cost more than the studs will.
+1

I just saw a horsepower show about why studs are better than bolts and this is exactly what they said.
 




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