Why stud bolts are stronger than bolts

Updated:28-05-2020
Summary:

Engine studs: understand the advantages of using studs […]

Engine studs: understand the advantages of using studs and bolts, and tips for obtaining proper clamping loads

 

In too many cases, the attention of engine manufacturers is only focused on selecting the right components for a specific engine manufacturing, determining the appropriate clearance, intake and exhaust volume and flow, surface finish, and precision assembly. Threaded fasteners are an important link that holds all components together and are usually taken for granted. Here, we will discuss various issues and concerns directly related to the most important components of any engine, such as studs and bolts and their operation.

Studs for engine applications can be used in most popular engines, especially in cylinder head applications. In contrast to bolts, the use of stud bolts in cylinder head installation provides a more accurate and uniform clamping load pattern across the cylinder head.
Studs for engine applications can be used in most popular engines, especially in cylinder head applications. In contrast to bolts, the use of stud bolts in cylinder head installation provides a more accurate and uniform clamping load pattern across the cylinder head.

 

Staple

For performance or heavy-duty applications, stud bolts are preferred over main bolts whenever possible, whenever possible. The stud can obtain a more accurate torque value, because the stud will not twist like a bolt during the tightening process. Since the stud stays still when tightening the nut, the stud only stretches on one axis, providing a more uniform and accurate clamping force. In addition, due to the use of stud bolts, the wear on the module threads is reduced, so the service life of the threaded holes in the module can be extended during maintenance / reconstruction. This is especially important when dealing with alloy ingots. The use of studs also simplifies the installation of the main cover and facilitates the alignment of the main cover. The chance of the main cap walking is small because the studs remain stationary during the cap clamping process.

Main cap bolt installation skills

Before starting the installation, please clean the module, cover and stud thoroughly. Any debris on the thread can easily affect the quality of the thread engagement and may result in an incorrect torque wrench reading.

 

If you plan to use cylinder head stud bolts, please use it from the beginning of the machining procedure. A set of studs (the same studs to be used during assembly) are used here to secure the cover plate during cylinder honing.
If you plan to use cylinder head stud bolts, please use it from the beginning of the machining procedure. A set of studs (the same studs to be used during assembly) are used here to secure the cover plate during cylinder honing.

To ensure that the internal threaded holes of the module are clean and even, they should be chased. Never use a cutting tip to perform this task, as this will cut, shave and remove thread material, which will reduce thread strength. Instead, only use a dedicated chasing thread tap, which will restore the thread by "forming" rather than cutting. Also make sure that the torque wrench is properly calibrated. The calibration of all torque wrenches should be checked at least once a year (more frequently if used frequently). Even new torque wrenches should be checked, because even some new wrenches cannot be calibrated up to 10 ft.-lbs.

 

Use consistent tightening techniques. In other words, don't open some nuts quickly, and don't open others slowly. The best way is to slowly "crawl" to a preset value. Quickly hitting the "ratchet" on the ratchet ratchet torque wrench will cause uneven and inaccurate values.

In most cases, only fix the bolt to the FINGER-TIGHT block, or screw in with a small preload (specific manufacturers may recommend a maximum preload of 8 to 10 ft.-lbs.). Do not add double nuts to the studs and tighten firmly. Remember, the torque value given during installation is only the tightening of the nut, not the stud itself!

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