We reached out to header bolt experts Mr. Gasket to find out what are header bolts, and why are they so important in protecting your car from exhaust leaks and horsepower losses.
1. What does the header bolt do and how does it affect my engine performance? It sounds like a really small thing, but as every racer knows, an engine can be entirely derailed by the loss of a tiny screw or bolt.
Mr. Gasket: The header bolt function is to provide a consistent clamp-load to seal the header flange, exhaust gasket, and cylinder head together. If the header bolt does not maintain a consistent clamp-load, an exhaust leak can occur. This starts with a slight ticking sound and can escalate into a full-blown (horsepower robbing) exhaust gasket failure because a piece of the exhaust gasket was blown out due to exhaust pressure leakage. The end result is purchasing and replacing the header gasket(s), which costs additional money and time to resolve the problem.
2. Is there a difference in the way headers and header bolts function in my daily driver, towing vehicle or performance/drag vehicle?
Mr. Gasket: Headers designed for daily driver (street use) and towing vehicles are similar. They are designed to increase engine low and mid-range horsepower and engine torque verse stock exhaust manifolds. Regular header bolts have a tendency to loosen-up do to engine thermo-cycling (heating up and cooling down) and engine vibration. They need to be re-torqued several times.
Performance Applications – Drag Race and Circle Track. Headers designed for true high-performance applications are designed to increase low, mid-range and top-end engine horsepower and torque up to 10,000 plus RPM. Again, regular header bolts have a tendency to loosen-up due to engine thermo-cycling (heating up and cooling down) and engine vibration. In these types of engines, internal engine vibration is more prevalent due to internal engine harmonics and stresses created above 6,000 RPM range. They also need to be re-torqued.
3. What should I be looking out for when purchasing or installing new header bolts?
Mr. Gasket: There are a lot of variables when purchasing header bolts. Number one is the condition of the engine exhaust port internal bolt threads. In some cases, internal threads are in good condition and in other cases, internal threads can be worn due to cleaning by thread chasing or extensive usage. If internal threads are worn, additional thread sealer will be required to help header bolt(s) maintain proper thread pitch engagement.
4. What’s the difference between the Headlock Header bolts and a traditional header bolt?
Mr. Gasket: Traditional header bolts are made from carbon steel and do not provide additional locking support to the bolt head or threads. These header bolts are usually zinc plated or have a black oxide finish, which will rust or corrode.
Mr. Gasket’s Headlock™ Locking Header Bolts provide additional locking support underneath the header bolt flange and threads. By adding locking serrations underneath the bolt head and a thread-lock patch to the bolt threads, Headlock header bolts provide additional locking support at the header bolt flange and threads. These header bolts are made from high-quality 300 stainless steel, Grade 8 material specification for strength, durability and corrosion resistance. The unique bolt head design incorporates a hex and socket head together to help ease installation. A ball-head hex socket tool is supplied to help start header bolt into mounting bolt holes. Note that a socket or wrench is required to finish applying the proper torque value to each header bolt.
5. How do these differences affect performance and what should I be looking out for after the installation of either a traditional header bolt or the Headlock bolt
Mr. Gasket: Traditional header bolts will loosen up due to engine thermo-cycling (heating up and cooling down) and engine vibration. They will need to be re-torqued several times. If the header bolts are not re-torqued, an exhaust leak will occur and lead to possible exhaust gasket failure.
Mr. Gasket Headlock™ Locking Header Bolts will not loosen up like traditional header bolts. By adding locking serrations underneath the bolt head and a thread-lock patch to bolt threads, Headlock header bolts provide additional locking support and improve thread engagement. We recommend the header bolts be re-torqued one time after the engine has gone through a complete thermos-cycle (heating up and cooling down). All header bolts will maintain the proper clamp-load required to keep the header flange sealed to the cylinder head.
6. Are these available for all vehicles and if not, are they more appropriate for certain vehicles?
Mr. Gasket: Headlock™ Locking Header Bolts are available for Chevrolet, General Motors, Ford, Chrysler and Dodge early and late model engines. Mr. Gasket Locking Header Bolts are available in U.S. (3/8-16”) and Metric (M8-1.25) thread sizes. These header bolts can be used in a variety of engine/vehicle applications based on the customer needs (header bolts that will not loosen up) or (header bolts that will not rust or corrode).
7. As an expert, what else do I need to know about maintaining my headers and header bolts. What sort of regular maintenance or tuning should I be doing and what expectations should I have for the life of these materials and parts?
Mr. Gasket: Header Maintenance.
Headers do tend to rust, so to prevent rusty headers keep the header flanges, tubes and collectors painted. Also, be sure to check the header flange for straightness. In some cases, the header flange may not be even or straight. Also, some headers are manufactured using a weld bead on the inside of the header flange. Check to be sure the weld bead is ground flat, occasionally they are ground uneven and cause gasket sealing problems.
Header Bolt Expectations.
Typical carbon steel header bolts need to be re-torqued several times before providing a consistent clamp-load to seal the header flange. Also, these header bolts will rust and corrode making the engine compartment less eye appealing.
Mr. Gasket’s Headlock™ Locking Header Bolts provide additional locking support underneath the header bolt flange and threads. By adding locking serrations underneath the bolt head and thread-lock patch to bolt threads, Headlock header bolts have additional locking support at the header bolt flange and improved thread engagement. We recommend the header bolts be re-torqued one time after the engine has gone through a complete thermo-cycle (heating up and cooling down). These header bolts are made from high-quality 300 stainless steel, Grade 8 material specification for strength and corrosion resistance. They will also save time and money. A purchase of Mr. Gasket HEADLOCK Header Bolts will provide a consistent clamp-load to the header flange, prevent exhaust leaks and gasket failure while maintaining a clean professional appearance to the header installation.
The end result is purchasing a set of locking header bolts that will provide a consistent clamp-load, prevent exhaust leaks and gasket failure, while maintaining a clean professional appearance to the header installation.