Lsa Exhaust Manifold Screw Size: What You Need To Know (2024)

The LSA engine is a powerful supercharged V8 engine, and like any other engine, it requires careful attention to detail when it comes to maintenance and repairs. One crucial aspect is the exhaust manifold, which plays a vital role in directing exhaust gases away from the engine bay. The LSA exhaust manifold is secured to the engine with screws, and knowing their exact size is essential for proper maintenance and upgrades.

LSx exhaust manifold bolts are M8 1.25 x 30mm

LSx Exhaust Manifold Bolts: M8 1.25 x 30mm

The LSx exhaust manifold bolts are M8 1.25 x 30mm. This specification is crucial when it comes to tightening the bolts on your LSx motor. The bolt torque, or turning force, is a delicate aspect that requires a careful approach to avoid leakage or damage.

Understanding Bolt Torque

When tightening bolts, it's essential to apply the correct amount of torque, or turning force, in a specific sequence. Too much torque can lead to bolt snapping or cast iron breakage, while too little torque can leave gaps, resulting in exhaust gas leakage. Therefore, achieving the right torque and following the correct sequence is vital.

LSx Exhaust Manifold Bolt Torque and Sequence

The LSx exhaust manifold bolts should be tightened in two stages. First, apply 11-12 ft-lbs of torque in the initial stage, followed by 18-20 ft-lbs in the final stage to securely hold the exhaust manifold in place. It's important to start with the centre bolts and then work your way outward, alternating from side to side.

Bolt Quality and Alternatives

The metric equivalent of grade 8 bolts, which are commonly used in standard applications, is metric 10.9. These bolts offer superior quality and can be sourced from hardware stores like True Value. If you're unable to find the required bolt size at Home Depot, True Value offers a more comprehensive selection of metric fasteners.

Bolt Maintenance

To ensure the longevity of your LSx exhaust manifold bolts, consider applying anti-seize lubrication. This will help prevent the bolts from seizing up and make them easier to remove in the future.

LS exhaust manifold bolt torque is crucial to avoid breakage or gas leakage

LS Exhaust Manifold Bolt Torque: Avoid Breakage and Gas Leakage

The LS exhaust manifold bolt torque is a critical factor when tightening bolts. Incorrect torque can lead to snapped bolts or cast iron breakage, while also leaving gaps for exhaust gas leakage. Therefore, it is crucial to establish the correct torque and sequence for tightening.

LS Exhaust Manifold Bolt Torque

The LS exhaust manifold bolts require a two-stage tightening process. For the first stage, begin with 11-12 ft-lbs of torque. Then, for the final stage, tighten the bolts to 18-20 ft-lbs to firmly secure the exhaust manifold. This two-step process ensures the bolts are tightened correctly and reduces the risk of damage.

It is important to tighten the bolts in a specific sequence. Start with the two centre bolts, then alternate from side to side, working towards the outside bolts. This ensures a tight and balanced torque distribution, reducing the chances of bolt breakage.

Bolt Sizing

The LS exhaust manifold bolts are M8 1.25 x 30mm. It is important to use the correct bolt size and type to ensure a secure fit and avoid damage. The metric equivalent of Grade 8 bolts is 10.9, which are suitable for LS engines.

Removing LS Exhaust Manifold Bolts

When removing LS exhaust manifold bolts, it is important to exercise caution to avoid breakage. Two effective methods for bolt removal are the heating method and the re-tightening method.

The heating method involves heating the bolt head for approximately two minutes, allowing the bolt and bolt hole to expand. Once cooled, use a hand torque wrench to twist the bolt open. This method takes advantage of the different cooling rates of steel and cast iron, helping to loosen the threads.

The re-tightening method uses penetrating oil to soften the threads. Apply the oil at least 12 hours before removal. This method also uses a loosening and re-tightening technique to break the holding threads.

Both methods use a reverse torque sequence to avoid bolt breakage.

The bolt torque sequence is also important to avoid damage

The bolt torque sequence is essential to follow when tightening the exhaust manifold bolts on an LSA engine. Incorrectly tightening the bolts can lead to a range of issues, from leaks to engine damage and failure.

The correct bolt torque sequence ensures an even distribution of load and torque across the bolts, preventing misalignment. When tightening bolts, it is best practice to tighten them in a crisscross pattern, starting from the centre and working outward in a diagonal pattern. This ensures a uniform clamping force across the entire cylinder head.

For example, if you have eight bolts, you would tighten them in the following order: 5, 2, 8, 3, 7, 1, 6, 4. This pattern helps to distribute the clamping force evenly, reducing the risk of misalignment and ensuring a secure seal.

When tightening the bolts, it is also important to do so in multiple stages. For LS exhaust manifold bolts, the first stage should be tightened to 11-12 ft-lbs, and the final stage to 18-20 ft-lbs. This gradual tightening process helps to gradually increase the clamping force and allows the engine components to settle into their proper positions.

It is also important to note that the tightening sequence is different when reusing bolts. In this case, you would start from bolt number one and work to the last bolt. However, this is not recommended for high-power engines as reused bolts may not be as efficient and can lead to leaks.

To remove LS exhaust manifold bolts, you can use the heating method or the loosening and re-tightening method. The heating method involves heating the bolt head for two minutes and then using a hand torque wrench to twist it open once it has cooled. The re-tightening method involves applying penetrating oil to the bolts at least 12 hours before opening, which softens the threads, making them easier to unscrew.

In conclusion, the bolt torque sequence is important to follow to avoid damage when tightening and loosening bolts. By following the correct sequence and using the appropriate techniques, you can help ensure a secure and leak-free connection.

LS exhaust manifold bolts are a one-time use bolt

LS exhaust manifold bolts are a one-time-use bolt. This is because they are designed with distorted threads that, when fastened, cause a locking effect that makes it difficult to unscrew and use them again. While it is possible to reuse them, it is not recommended as it is less efficient, and the bolts may snap if excessive force is applied.

The bolts are typically M8 1.25 x 30mm, and they are metric. The stock manifold bolts are 10mm, and the threads are fine. The bolts have two stages of tightening. The first stage involves tightening the bolts to 11-12 ft-lbs, and the final stage involves tightening them to 18-20 ft-lbs. This two-step process helps to ensure a tight fit and prevent exhaust gas leakage.

When removing LS exhaust manifold bolts, it is important to exercise caution as they can break easily due to the pressure from the bolt torque. There are two recommended methods for removing these bolts without breaking them: the heating method and the loosening and re-tightening method. The heating method involves heating the bolt head for about two minutes and then using a hand torque wrench to twist it open once it has cooled. The re-tightening method involves applying penetrating oil to the bolts at least 12 hours before removal. This helps to soften the threads, making it easier to unscrew the bolts.

It is worth noting that some people have expressed frustration with the design of LS exhaust manifold bolts, particularly regarding their tendency to break and the difficulty of removing them. However, others have found success with techniques like welding, heli-coiling, and using anti-seize compounds.

There are methods to remove LS exhaust manifold bolts without breaking them

LS exhaust manifold bolt torque is a crucial factor to consider when tightening bolts. Too much torque can lead to bolt snapping or breakage of the cast iron, while less torque leaves gaps for exhaust gas leakage. Therefore, it is essential to establish the correct torque and sequence for tightening the bolts.

The bolt torque should be maintained at 11 ft-lbs for the first pass and then tightened to 18 ft-lbs. When tightening the bolts, use a hand torque wrench to avoid exerting extreme torque, which could break the bolts. Additionally, use star-shaped washers for a better grip and avoid open flat washers as they slide while unscrewing.

There are two methods to remove LS exhaust manifold bolts without breaking them: the heating method and the loosening and re-tightening method.

The Heating Method

The heating method requires heating the bolt head for about two minutes and then allowing the bolt to cool down. Once cool, use a hand torque wrench to twist it open. This method utilises the principle of expansion and contraction of the bolt and the bolt hole. When heated, the bolt and bolt hole expand. On cooling, the bolt, made of steel, cools faster than the cast iron block, causing the lock-tight threads to loosen.

The Re-Tightening Method

The re-tightening method uses penetrating oil to soften the threads holding the bolt. Apply the oil at least 12 hours before opening. The oil will penetrate the threads, making it easier to unscrew the bolts. This method also involves loosening and re-tightening the bolt to break loose the holding threads.

Both methods use the reverse torque sequence to loosen the bolts and avoid breaking or snapping.

Other Tips to Avoid Breaking Exhaust Manifold Bolts

To avoid breaking exhaust manifold bolts, it is important to address the common reasons why bolts break in the first place. One reason is that exhaust manifold bolts are often not removed for a long time, leading to rust. The build-up of rust diminishes the bolt's patch, and when force is applied to remove the bolt, it breaks.

To remove rusty bolts, use a penetrating spray to free them up. Apply the spray to each bolt and leave it for a few minutes to react. After this, the bolts should be loose enough to remove.

Another reason bolts break is that people do not know the proper steps to remove them. It is important to be patient and careful when removing old and rusty bolts. Additionally, make sure to use the right wrench for the bolt's head. Picking the wrong wrench can result in broken bolts.

When removing the bolts, spin the wrench anti-clockwise, but do not apply too much force at first. Slowly remove the bolts one by one.

Frequently asked questions