Which head studs?
11-12-2009, 09:51 PM
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Which head studs?
I have a 06' LQ4 that I am needing some ARP head studs and I am trying to figure out which ones to get. One kit has 4 shorter bolts then the rest. Any help? Thanks Thomas
11-14-2009, 08:44 AM
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If you haven't already picked them up, go with the 12pt nuts ARP# 234-4317.
http://www.sdparts.com/product/ARP23...LS12004Up.aspx
Rick
http://www.sdparts.com/product/ARP23...LS12004Up.aspx
Rick
11-14-2009, 08:47 AM
#6
If you haven't already picked them up, go with the 12pt nuts ARP# 234-4317.
http://www.sdparts.com/product/ARP23...LS12004Up.aspx
Rick
http://www.sdparts.com/product/ARP23...LS12004Up.aspx
Rick
11-14-2009, 02:20 PM
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I've read that at high torque readings (something like 200+), the 12pt spreads the load out more evenly than a 6pt. I don't think that is relevant at our torque levels. ARP actually added the 12pt option back in the day for valve spring clearance on old school small blocks. Large diameter valve springs would block access to a 6pt nut.
Regarding the studs verses bolts, this is clearler than anything I can write:
HEAD STUDS vs. BOLTS...
A TECHNICAL DISCUSSION
ARP’s factory Tech Representatives are often asked which
is better, cylinder head studs or bolts. The answer, invariably,
depends on the installation. On many street-driven vehicles,
where 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.
And for good reason. Using studs will make it much easier to
assemble an engine (especially a racing powerplant which must
be serviced frequently and quickly!) with the cylinder head and
gasket assured of proper alignment.
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.
Rick
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11-14-2009, 03:34 PM
#9
...A 12pt socket has more clamping sirface than a 6pt so there is less chance of stripping a nut.
I've read that at high torque readings (something like 200+), the 12pt spreads the load out more evenly than a 6pt.
Regarding the studs verses bolts, this is clearler than anything I can write:
HEAD STUDS vs. BOLTS...
A TECHNICAL DISCUSSION
ARP’s factory Tech Representatives are often asked which
is better, cylinder head studs or bolts. The answer, invariably,
depends on the installation. On many street-driven vehicles,
where 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.
And for good reason. Using studs will make it much easier to
assemble an engine (especially a racing powerplant which must
be serviced frequently and quickly!) with the cylinder head and
gasket assured of proper alignment.
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.
Rick
I've read that at high torque readings (something like 200+), the 12pt spreads the load out more evenly than a 6pt.
Regarding the studs verses bolts, this is clearler than anything I can write:
HEAD STUDS vs. BOLTS...
A TECHNICAL DISCUSSION
ARP’s factory Tech Representatives are often asked which
is better, cylinder head studs or bolts. The answer, invariably,
depends on the installation. On many street-driven vehicles,
where 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.
And for good reason. Using studs will make it much easier to
assemble an engine (especially a racing powerplant which must
be serviced frequently and quickly!) with the cylinder head and
gasket assured of proper alignment.
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.
Rick
Nonetheless, I had to use some 12pt bolts on headers on either my older truck or this 1, can't remember which. The 6 pt bolts included w/. headers from header manufacter didn't work in a few instances. Go figure.
Cause I wasn't bout to crush/ crease tube for clearance. Re-torque after running due to compression of gasket. - A person can learn something on PT if they try.
11-14-2009, 06:42 PM
#10
I agree that the 12 point will make a head swap quicker and easier with the engine in the truck, but if someone's rounding head bolts off they either need better tools or should just drop the tools and step away....If I were building the engine on the stand I'd use 6 point fasteners and a quality SnapOn FlankDrive socket
How much power are you pushing that you need head studs? The LQ9 I'm building is fairly mild, maybe 485 estimated crank HP, so I'm just going to use factory GM torque to yield bolts...torque em once and run with it. If you have to pull the heads off with the engine in the truck, the studs may give you a problem...although the studs in question *should* come out by hand...
How much power are you pushing that you need head studs? The LQ9 I'm building is fairly mild, maybe 485 estimated crank HP, so I'm just going to use factory GM torque to yield bolts...torque em once and run with it. If you have to pull the heads off with the engine in the truck, the studs may give you a problem...although the studs in question *should* come out by hand...