Just some guy. You don’t need seriously strong bolts just to fasten manifolds to the heads.
Grade 5 is fine
. I’ve never seen a regular manifold bolt that wasn’t rusty though, the corrosion resistance of stainless is definitely a plus.
Can I use bolts instead of studs for exhaust manifold?
Super Moderator. I agree, the bolts in place of studs and
nuts would be okay
. Be sure to observe the torque specs for the bolts, i.e. to be the same as the nuts on the studs. You dont want an exhaust manifold to be too tight – it interferes with the manifold expanding at a different rate than the head.
What are exhaust manifold bolts made of?
RE: Exhaust Manifold Bolts
Use
stainless steel bolts or studs
.
Do I need special bolts for headers?
For secure fitment, header bolts need
maximum thread engagement
, without bottoming out in the cylinder head. … Most headers with 1/4-inch or 5/16-inch thick flanges will use bolts with a 3/4-inch UHL, while 3/8-inch thick flanges normally require bolts with a 1-inch UHL.
What does Grade 8 mean for a bolt?
Grade 8 – Grade 8 bolts are made from
medium carbon alloy steel
. The bolts of this grade feature 6 radial lines. The nominal size of the grade 8 bolts can be from 1/4′′ to 1 1/2′′. The minimum yield strength of this grade bolt is 130,000 psi.
What are bolt grades?
The grade of a bolt
determines the maximum amount of stress (tensile strength) that the bolt can handle
. … The SAE marking system uses raised dashes on the bolt head to indicate strength. Metric Bolt Grades—Metric grades are set according to rules set by the ISO (International Standards Organization).
Why are exhaust studs Not bolts?
Studs provide the ability to obtain much more accurate torque values because the
studs don’t twist during tightening as do bolts
. Because the studs remain stationary during nut tightening, the studs stretch in one axis alone, providing much more even and accurate clamping forces.
Can I use bolts instead of studs Turbo?
DO NOT use bolts for the turbo connection
; they will back out after a few heat cycles. The mechanical way the stud/nut works puts more tension on the stud to block (or turbo) side, then the nut side of the assembly allows for the thermal expansion without loosening.
Should you replace exhaust studs?
In addition, we recommend
replacing all
of the bolts with OEM mounting bolts or studs. When you replace the manifold with a new one, it will be prone to the same warping that broke the bolt originally – so at the very least, be sure to replace all of the bolts with OEM mounting bolts or studs.
Can you use stainless steel bolts on exhaust?
There’s
nothing wrong
with them on exhaust systems but you really can’t put any serious torque on them because they are much lower tensile strength than alloy steel. They will stretch more so have to be tightened more than once after break in (in this application.
Should I use Grade 5 or Grade 8 bolts?
Grade 8 bolts have been
hardened more than grade 5 bolts
. Thus they are stronger and are used in demanding applications such as automotive suspensions.
Are Grade 8 bolts heat resistant?
Alloy steel is made from high-strength steel alloy, heat-treated, so that would be the grade eight. These are all alloys. Grade 8
is heat treated
. These, over-time, just so you know, have a zinc finish on them and they do not have any long-lasting rust resistance at all.
Is Grade 8 the strongest bolt?
Commercial-grade 8 bolts are
the strongest option available
. They’re made from medium carbon alloy steel and have markings that include six raised dashes. The psi of the bolt is 150,000, meaning that it can withstand great deals of pressure because of the way it was quenched and tempered.
How hard is a Grade 8 bolt?
A grade 8 bolt is the highest grade SAE bolt. Grade 8 bolts have a
minimum tensile strength of 150,000 PSI
.
What is a grade 8.2 bolt?
Hex Head Serrated Flange Screw Grade 8.2 is
a cap screw made from 10b21
. It has a greater tensile strength than grade 5. The serrated hex flange machine screw is designed for use in high stress applications. The 10B21 is a low carbon steel with Boron, used for making cold headed bolts which improves hardenability.
How do you know if a bolt is grade 8?
English bolts have radial lines on their head to identify the grade, or strength class. The number of lines on the bolt head is 2 less than the actual grade. So, for example, a grade 5 bolt will only have 3 radial lines on its head. A grade
8 bolt will have 6 radial lines on its head
.
Are all exhaust studs the same?
Registered. The studs and nuts are NOT the same, but they
are the SAME thread size and pitch
.
Can I reuse exhaust manifold bolts?
You could reuse them
, if you think they look good, but your chances of one breaking later have gone up now. I replace them every time, just heat the area around the studs, and melt a candle or crayon into the threads, let cool, they should come out easy, may need to heat again.
Why do exhaust manifolds use studs?
Removing the Manifold
In our case, the Hemi exhaust manifolds use four studs and five bolts. The
studs hold the heat shield in place
. … With all the bolts removed, the manifold and gasket were removed, exposing the broken studs in the cylinder head.
What is better head bolts or studs?
In other words,
head studs
are better suited for high-performance vehicles with greater power requirements, while head bolts are more practical for personal, everyday automobiles.
How much does it cost to replace exhaust manifold bolts?
Your exhaust manifold repair will cost you
between $570 and $900
, with labor taking up $400-$550 of that, and parts running between $130 and $340.
Should I replace my exhaust manifold?
A faulty manifold must be taken off and inspected,
and replaced with new manifold
. … Unfortunately, the exhaust manifold is an absolutely critical component to your vehicle, and if you ignore your cracked manifold, the problem will only get worse and more expensive.
Why do exhaust bolts have springs?
It’s there
to prevent vibrations
. They keep the exhaust sealed but allows the joints to flex under engine movement.
Are zinc bolts strong?
Hot-dipped galvanized zinc metal alloy screws (boy that is a mouth full) have a
tensile strength of 62,000 PSI
since they are grade 2 bolts. There are, however, more expensive versions of zinc bolts such as grade 5 and grade 8 that are common. Grade 5 has a max threshold of 120,000 while grade 8 tops out at 150,000.
Are all exhaust flange bolts the same?
The most common options of exhaust flanges are the
2 bolt or 3 bolt type but 4 bolt are also available
. Generally you would use a m10 bolt with the 2 bolt option and a m8 bolt for the 3 bolt. The grade of bolts we recommend are a 8.8 tensile or higher so they can be tightened without breaking or stretching the bolts.
How tight should exhaust manifold bolts be?
Every vehicle has different levels of torque necessary to properly tighten its bolts. The standard is to use
20 to 30 foot-pounds of torque
.
What is the meaning of 8.8 grade in a bolt?
In the case of a 8.8 grade bolt the first figure signifies that
the Tensile Strength is at least 800MPa
. The second figure signifies that the fastener will begin to yield at 80% of the Ultimate Tensile Strength, i.e. at least 640MPa.
Are Grade 8 bolts or Grade 5 shear easier?
There exists an often quoted myth, that Grade 5 bolts are better in shear than Grade 8 since they will bend before breaking.
Not true
. Shear strength of alloy steel is approximately 60% of its ultimate tensile strength.
What grade bolt has the highest shear strength?
- 12.9 Bolts. A 12.9 bolt is one of the highest grade of bolts produced. Known for their high tensile strength, they are built with both hex and Torx heads and are available in zinc or chrome finishes. …
- 12.9 Shear Strength. The minimum tensile strength of a 12.9 bolt is 1220 MPa.
Can you weld a Grade 8 bolt?
If you weld a Grade 8 bolt,
you could soften it to the strength that Grade 5 possesses
. No matter how little heat you use, heating the bolt in uncontrolled conditions will weaken it.
How many pounds can a Grade 8 bolt hold?
The tensile strength of a grade 8 bolt is
150,000 pounds per square inch
. Tensile strength is the maximum load in tension (stretching) that a part can carry without breaking.
How much stronger is a Grade 8 bolt than a Grade 5?
Typically, fasteners are not brittle below 180 ksi ultimate tensile strength. Grade 5’s have an ultimate tensile strength of 120 ksi and a grade 8 fastener has an ultimate
tensile strength of 150 ksi
.
