Every build will be different, which is equivalent to a slightly different answer to the question "what is the correct way to build a motor or set up a power supply?" Every experienced builder should find his own secret of success.

When discussing bearing clearance, you will find that the formula will vary from manufacturer to manufacturer. Differences in motor use, specific platforms, preferred oil and fuel supply systems, and operating and ambient temperatures also need to be taken into account. We will discuss the basic theories of LS power supplies, bearings and related factors.

When discussing the basics of the main hole, many important factors are the alignment of the main hole, the perfect round hole, the tension of the main cover and the consistency of the main hole size. All main holes are honed with a single honing head and multiple grindstones, which can form a perfect hole line without any deviation. If the main hole is placed in the center before the honing process, the main hole misalignment can be solved The problem. When using a single honing head, size/roundness can be an issue because material is removed from hole to hole at different speeds. This can be solved by many different technologies. Due to the technical nature of the process, this needs to be written in a separate article. 

The tension on the main cap is another important factor that affects the roundness/straightness repeatability of the main hole. GM LS blocks, except for a few, rely only on the registration pressure to achieve the repeatability of the cap position. If the adjuster becomes loose and loses tension when the cover is removed and installed for assembly, it may be misaligned and cause problems with the roundness and straightness of the hole and the thrust surface. This is common in many aluminum blocks and must be solved by adding king pins or pins. 

Pins and/or pins will ensure that the position of the main cover is consistent. This will ensure that the main hole remains constant on the block during the build process. If the block starts to twist or the main fastener fails to stay properly in place under high stress, this will also keep the main cap in its proper position. 

Once you have ensured that the holes are correct, the next important area is the bearing. Each manufacturer and block has a difference in the position of the oil supply hole and the eccentricity of the bearing on the inner surface of the oil supply to support the crankshaft. For different bearing housing and bearing manufacturers, it is very important to ensure that the selected bearing uses the same location as the oil supply source. 

When looking at the eccentricity of the bearing, you will find that different oils, operating temperatures, speeds, oil system design, power levels and types of use will all play a role in the ever-changing demands of eccentricity. The concept is to create a wedge-shaped oil at the parting line between the main cover and the block. The 6/12 o'clock position of the bearing is tighter than the 3/9 o'clock position, creating space for the oil wedge required to properly protect the crankshaft and the bearing. Again, this will vary based on usage, but the general difference will be four numbers, which means you can see the inner diameter increase at the parting line from 0.0001˝-0.0005˝.

Different bearings and their uses will also play a role. When selecting bearings, be sure to discuss your intended use with the specific manufacturer and let them determine your application needs. You will see Bi and Tri-metal as well as coating and plating options from most major manufacturers. This is another discussion in itself, and you should have an in-depth discussion with the manufacturer or manufacturer of your choice when making the final choice. 

It is also necessary to resolve the difference in the width of the bearing and the depth of the chamfer. With a stock crank build, you will use a female radius, which means that the radius is retracted into the crankshaft, resulting in a wider bearing surface, and there is no chance of hitting the radius at the edge of the bearing. The aftermarket crankshaft will have a standard radius that extends into the location of the original bearing surface. This creates the need for narrowed or chamfered bearings. The radius diameter varies by manufacturer or crankshaft class, and usually increases with the expected power class. If the wrong combination is used, it will result in metal-to-metal contact or reduced oil film, which will eventually lead to catastrophic failure.

Thrust or crankshaft end play is another tolerance that changes constantly depending on the application. In inventory construction, tolerances as small as 0.004˝ are usually seen, and as large as 0.012˝ in extreme applications. The same general factors will apply to the location that will be set. An important influencing factor we found is the need to add extra clearance on vehicles that span the brakes for an extended period of time, especially vehicles with power adders. 

When looking at issues such as the extended sliding valve time on the turbocharger, you will find that due to extreme high temperatures and increased pressure, additional room for torque converter growth is required. The back of the bearing is the main target of pressure. We found that by adding an extra oil supply galley behind the thrust bearing, you can control the extra oil that exerts extra pressure between the bearing and the crank. This helps to extend the life of bearings and crankshafts under these extreme conditions. 

We recommend that you make a note of your initial end clearance on the construction for tracking, so as to quickly check whether there is a concern about excessive crankshaft pressure or bearing damage when the motor is installed in the vehicle. The way the crankshaft signals are considered is also important, because if the thrust is too high, the inventory system may start to malfunction. Certain extreme applications will require flying magnets or an external crank signal system. 

It is also important to hit back the main cap tension, pin or pin. If the cap is fixed, the pin or tension is not correct, the thrust may be changed due to the incorrect placement of the main cap. It is very important to ensure that the lid/thrust surface is at right angles to the power supply to prevent any problems.

If you have been on LS for a while, especially on impact motors, you may have seen the #2/4 main bearing failure. There are many ways to solve the problem of premature bearing wear or damage. When discussing problems and solutions, we will assume that all the conditions mentioned above have been solved and correct, which means that we are looking for problems other than the slider/bearing. 

Using the original LS crankshaft design, no counterweight is used in the center of the crankshaft. In higher power and speed applications, the oscillation of the crankshaft will start at the extremes seen in the #2/4 main bearing. In recent years, the introduction of a central counterweight crankshaft on the LS platform has become a solution. However, this is not always feasible, as many aftermarket crankshafts do not offer a center weight option. #2/4 The bearing clearance on the main bearing can be slightly changed to allow extra space under crankshaft deflection. This is not a way to solve basic problems, but a way to use universal design.

If we look outside the main power supply, motors with large blowers or superchargers also have problems. When an increased torsional strain is applied to the nose of the crankshaft, if it is not addressed, it will damage the #1 trunk line. This can be solved with some external bearing options to stabilize the nose of the crankshaft and reduce the load on the #1 main bearing.

Finally, it is important to remember that every build will be different, which is equivalent to a slightly different answer to the question "What is the correct way to build a motor or set up a power supply?" Every experienced builder should find his own secret of success, because there is no answer to any of the above questions. Finally, it is best to discuss these issues in depth with your manufacturer or part manufacturer to find the specific needs of your specific build. EB

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