ARP bolts vs. studs question
Thread Starter
Racer
Joined: Aug 2009
Posts: 278
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From: Warminster PA
ARP bolts vs. studs question
My car (98 coupe) is a H/C/I car with no plans for boost. My engine builder is about to install the heads. He has ARP bolts he will give me for free. Should I use them or purchase the studs?
What do you think? Free bolts or get the studs?
What do you think? Free bolts or get the studs?
Race Director
Joined: Nov 2000
Posts: 10,340
Likes: 664
From: Beverly Hills (Pine Ridge) Florida
But from a disassembly standpoint, studs can be a pain.
Go with the bolts.
Plasticman
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Melting Slicks
Joined: Dec 2003
Posts: 3,315
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From: Near Jacksonville Fl.
"If higher cylinder pressures are seen or planned for in the future (from whatever source), the studs are better at clamping the head evenly."
Please, somebody tell me where this fairytale came from.
The only difference between the ARP head bolts and studs is the price!
They are the same number of clamps (bolts or studs) determined by the number of threaded holes and the same size.
The also use the same size washers under the heads of the bolts as under the nuts on the studs.
The torque is the same and the block material doesn't change, so where is the advantage?
It comes from numerous removals of the heads, you don't wear the threads in the aluminum block.
In fact from a mechanical standpoint they are more prone to failure then bolts since they add 2 more threads per connection!
Please, somebody tell me where this fairytale came from.
The only difference between the ARP head bolts and studs is the price!
They are the same number of clamps (bolts or studs) determined by the number of threaded holes and the same size.
The also use the same size washers under the heads of the bolts as under the nuts on the studs.
The torque is the same and the block material doesn't change, so where is the advantage?
It comes from numerous removals of the heads, you don't wear the threads in the aluminum block.
In fact from a mechanical standpoint they are more prone to failure then bolts since they add 2 more threads per connection!
Last edited by corvettebob1; Jan 17, 2010 at 02:57 PM. Reason: spelling
Race Director
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From: Raleigh, NC
St. Jude Donor '15
Team Owner
Joined: Sep 2001
Posts: 23,283
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From: Lake Elsinore, CA
Here's another perspective - I used studs when I did my h/c install several years ago. I bought them with the h/c package from a tuner along with several other upgrades like hardened pushrods and Cometic head gaskets.
Turned out I had issues with the head gaskets which took a while to sort out. I ended up removing/reinstalling the heads 4 times in a month to resolve that issue. Considering what a PITA it is to clean out those head bolt holes in the block, and the consequences if it's not properly done, I was extremely grateful for the studs as I didn't have to soak the coolant out of those bolt holes every time I pulled those heads. From that standpoint, I will lean towards the studs when I do my next build. Also, pulling and installing the heads with studs on a C5 with the engine still in the bay is no big deal - the heads go on/come off with no problem. JMHO.
Turned out I had issues with the head gaskets which took a while to sort out. I ended up removing/reinstalling the heads 4 times in a month to resolve that issue. Considering what a PITA it is to clean out those head bolt holes in the block, and the consequences if it's not properly done, I was extremely grateful for the studs as I didn't have to soak the coolant out of those bolt holes every time I pulled those heads. From that standpoint, I will lean towards the studs when I do my next build. Also, pulling and installing the heads with studs on a C5 with the engine still in the bay is no big deal - the heads go on/come off with no problem. JMHO.
Burning Brakes
Joined: Feb 2001
Posts: 793
Likes: 2
From: Milwaukee & Long Beach WI & CA
"If higher cylinder pressures are seen or planned for in the future (from whatever source), the studs are better at clamping the head evenly."
Please, somebody tell me where this fairytale came from.
The only difference between the ARP head bolts and studs is the price!
They are the same number of clamps (bolts or studs) determined by the number of threaded holes and the same size.
The also use the same size washers under the heads of the bolts as under the nuts on the studs.
The torque is the same and the block material doesn't change, so where is the advantage?
It comes from numerous removals of the heads, you don't wear the threads in the aluminum block.
In fact from a mechanical standpoint they are more prone to failure then bolts since they add 2 more threads per connection!
Please, somebody tell me where this fairytale came from.
The only difference between the ARP head bolts and studs is the price!
They are the same number of clamps (bolts or studs) determined by the number of threaded holes and the same size.
The also use the same size washers under the heads of the bolts as under the nuts on the studs.
The torque is the same and the block material doesn't change, so where is the advantage?
It comes from numerous removals of the heads, you don't wear the threads in the aluminum block.
In fact from a mechanical standpoint they are more prone to failure then bolts since they add 2 more threads per connection!
Studs also provide more accurate and consistent torque loading. Here's why. When you use bolts to secure the head, the fastener is actually being "twisted" while it's being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. A stud should be installed in a "relaxed" mode - never crank it in tightly using a jammed nut.
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.
Former Vendor
Joined: Nov 2008
Posts: 146
Likes: 0
From: Virginia Beach Virginia
the other thing that needs to be considered when cmparing studs to bolts is the thread angle.Torque is a measurement of friction not stretch.The shallower thread angle on the nut side of the stud will provide more stretch at the same torque reading.The shallower thread also make for more consistant stretch.Studs have many benefits over the bolts.
But to answer the OP's question-the bolts will be fine in your application
But to answer the OP's question-the bolts will be fine in your application
Melting Slicks
Joined: Dec 2003
Posts: 3,315
Likes: 17
From: Near Jacksonville Fl.
From schpenxel's link:
Studs also provide more accurate and consistent torque loading. Here's why. When you use bolts to secure the head, the fastener is actually being "twisted" while it's being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. A stud should be installed in a "relaxed" mode - never crank it in tightly using a jammed nut.
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.
Studs also provide more accurate and consistent torque loading. Here's why. When you use bolts to secure the head, the fastener is actually being "twisted" while it's being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. A stud should be installed in a "relaxed" mode - never crank it in tightly using a jammed nut.
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.
In all honesty I like to see a real side by side comparison using objective data proving the "More even clamp load and twist theory."
Drifting
Joined: Jul 2002
Posts: 1,484
Likes: 0
From: Morgan Hill Ca.
I used the ARP bolts when I did mine, I did think about the studs but after discussing with ARP, they thought that there might be a problem installing a head over the studs with the engine in the car. Soooo What I am hearing is the heads will clear between the overhang of the cowl and the studs with no problem???
Comments?
Comments?
