MLS head gaskets. Engine sealing tips and tricks (2023)

Any business owner or lifelong self-obsessed with doing most of their work knows the value of things that go beyond money. First of all, time is huge. It pays to work on your own stuff, but no one likes to do a job multiple times. Using good tools is key to success - as is knowing that the work you're doing will be solid.

Success on the track, street and/or playground depends on preparation. Many people who don't have the same success as others, but try everything they can think of, often blame money or politics. However, the truth is different. Successful people know a few tips, tricks and techniques for prioritizing things in ways that less successful people can see as luck or even magic.

MLS head gaskets. Engine sealing tips and tricks (1)

MLS seals consist of two to five carbon steel springs or sheets sandwiched between the head gasket material. Precisely shaped beads and stops work with the specific properties of the steel to increase clamping force around the combustion chamber.

Speaking of "magic", if you don't know enough about multilayer steel (MLS) head gaskets, it will change your automotive life. Everyone focuses on creating big things that are generally flashy, exciting and expensive. But all these parts must work together. Preferably without breaking.

Head gaskets are incredibly important, but you hardly think about them. Enthusiasts purchase a replacement gasket kit and install the gasket in the required locations. However, head gaskets must withstand millions of explosions, expansion and contraction of various metals, various chemicals and extreme temperatures. Basically, they are expected to work silently and flawlessly forever.

MLS Head Gasket Science

We contacted two leading sealing companies,funnyIkiller forfix the "spell". We have used products from these two companies in the past. It turns out that even our jaded and sometimes arrogant selves learned a lot of really important information. This is why writing this article was very useful.

No additional coatings are required for MLS head gaskets. – Jim Daigle one hell of a professional

Fel-Pro Chief Engineer Rich Larson and Senior Product Manager Jim Daigle walked us through the details. The history of Fel-Pro goes back 101 years. It was then that the company began manufacturing felt products and made a breakthrough in the production of gaskets for the Ford Model T. A century later, the company became the market leader in automotive gaskets.

MLS head gaskets. Engine sealing tips and tricks (2)

Fel-Pro PermaTorque MLS high performance head gaskets are designed and built to maintain the necessary contact stress to seal the pressures and combustion temperatures commonly encountered in high compression naturally aspirated, supercharged, turbocharged and nitrous oxide injected engines.

"Established in 1989, Cometic has been dedicated to serving the powersports industry," said Mickey Hale. “To this day, Cometic products are 100 percent made in the USA and use state-of-the-art technology to create high-quality, custom seals for every application. The company is also family owned. Cometic is a customer-centric company and is able to offer first-class craftsmanship direct to the racing shops, and even a one-of-a-kind piece for the little man.”

MLS head gaskets. Engine sealing tips and tricks (3)

When you need to change the bore size and/or gasket thickness, the process starts with a phone call. Once Cometic's in-house technical sales team understands your needs, they will work directly with designers to create exactly what you need.

MLS head gaskets are exactly what the name suggests. These are very thin stainless steel plates held together and coated with special surface coatings. They also have a relief that makes it easier to seal when they are tightened. Generally, these seals consist of three layers, but there are special seals that can have up to seven layers, depending on the application and needs.

MLS head gaskets. Engine sealing tips and tricks (4)

MLS fillings generally cost more than composite fillings.

What makes MLS technology so special is its ability to handle higher workloads and achieve better sealing performance with much less effort. If we look at old-fashioned composite head gaskets that use a fire ring, the basis of comparison becomes clear, which makes MLS superior. Not only is MLS used everywhere in modern OEM vehicles, it will continue to improve over time and will likely be the choice for the future of the internal combustion engine. There is almost no reason not to use MLS head gaskets in your application.

Geeky details make a big difference!

Due to the plug and bead nature of the bore (stamping) and the elastic action of the metal, it is now much easier for the builder to achieve a tight seal on the combustion chamber. This means that less torque is required for cap screws or studs. It's also more forgiving when torque isn't applied evenly. Do not take this as a reason for an installation accident. We're just saying this seal protects your back like no other. This is also of great importance to OEMs looking for performance, emissions control and efficiency. Since less torque is required to produce the same seal, there is less chance of casting deformation and cylinder wall deformation.

MLS head gaskets. Engine sealing tips and tricks (5)

Both old and new engines can benefit from MLS technology. However, if your engine was originally designed to use composite seals, you should have the surfaces checked to make sure they are smooth enough for MLS seals or have them refinished.

Special coatings on MLS seals seal two surfaces at a microscopic level. When you first start the engine and warm it up, the gasket becomes chemically bonded to the metals. Important note: this is also the point of no return, so the stamp cannot be reused. The MLS head gasket can be cold tightened several times before final assembly only if the surfaces are smooth and clean.

MLS head gaskets. Engine sealing tips and tricks (6)

Ready to install, no additional coating required

Thermal cycling and dissimilar metals are the scourge of head gaskets. How many people are afraid that their head gasket will blow when their car warms up? MLS head gaskets are the best design to withstand the movement of various metals that expand and contract during engine thermal cycles. Think of it this way: those multiple layers can slide over the microscopic layer instead of being subject to the laws of physics trying to tear apart your old-school composite gasket.

Be tailored

Why are there different amounts of shifts? Different applications and head and block modifications have specific requirements. For example, you might want to slightly change the compression ratio or adjust the damping range.

MLS head gaskets. Engine sealing tips and tricks (7)

A good sealing surface means not only smooth, but also flat. Checking surface waviness and roughness helps determine the durability of the MLS seal.

At Cometic, gasket thicknesses range from 0.027 to 0.140 inches. MLS gaskets have a very wide range of thicknesses that seal effectively and are just as reliable as thinner gaskets. This is not to say that it is a cure for improperly built engines or salvaging an old cylinder head that has been ground one too many times.

For example, it is possible to go from a .040-inch to a .080-inch gasket in a big block and lower the compression point if you want to avoid detonation in a forced-induction engine. Of course, being able to change the thickness of the gasket also gives you the ability to fine-tune the quench area.

Adjusting the head gasket thickness is really just for fine tuning. – Mickey Hale, Cometic

Mickey pointed out, "People are too attached to the delete. Unless your build is already matched to perfection, there are more important things to get right, like the compression ratio. Adjusting the head gasket thickness is really just fine-tuning."

do you have an incentive

Cometic also offers the MLX seal line, which is a special tool seal. While not infinitely variable in design like the MLS gasket, it has a ring around the combustion chamber that laughs at over 20 pounds of boost.

MLS head gaskets. Engine sealing tips and tricks (8)

MLS seals can be very forgiving, but only under strict conditions. The surfaces of both the block and the head must be sufficient to allow proper sealing. The roughness tolerance of the sealing surfaces is significantly lower - almost half of what is possible when using a bonded gasket. The smoother the better.

Myths and hot tips

We asked both Cometic and Fel-Pro two very important questions. Why should someone buy from your company or establish a relationship with you? And what do you wish people knew but can't reach?

Fel-Pro is happy to emphasize that the company is a leader in the sealant industry. The strength of the company lies in the production of a wide range of seals for different requirements. It can back them up with rigorous real-world testing and quality control.

MLS head gaskets. Engine sealing tips and tricks (9)

The Fel-Pro lower cost composite gasket still has a place in the performance world.

Cometic emphasized that they are performance focused head gasket specialists, not just a one-stop shop. Building relationships allows the artist to grow as they can customize each stamp. You can buy the products at places likeIsorrace to the top, or you can call them directly for your needs.

MLS head gaskets. Engine sealing tips and tricks (10)

Several sheets of stainless steel are stacked to achieve the desired thickness. The MLS gasket's ability to protect against blowout in high cylinder pressure situations is due to the molded layers that act as a "spring" to provide increased head lift. The outer layers are embossed, but also have a special coating that helps to adapt to the surfaces of the head and block.

Daigle wanted people to know, “No additional coatings are required on MLS head gaskets. As long as your surface preparation is correct, gaskets are specifically designed for use with properly prepared bare metal. This means a properly bonded and flat surface with a finish of 70Ra or less.” Ravalue is a measurement of surface roughness. He also wanted to make builders aware that today's high-tech lubricants can make the threads of bolts and studs so slippery that the bolt can easily loosen. This means that the correct torque reading may be displayed, but you have over-tightened the screw or bolt. Finally, keep the sealing surfaces clean and dry.

MLS head gaskets. Engine sealing tips and tricks (11)

Just as important as the gasket is the order in which you tighten the head fasteners. Always start with the screw or stud in the center and then spiral outward. This distributes the load evenly across the head gasket for maximum strength.

Cometic wanted to add: if you change the head gasket thickness, remember that the pushrod length and gasket thickness may need to change as well. Also,it isDo not use copper sprays on the product. It is designed to be used without it. After all, your fasteners (shear pins and studs) are critical. Be sure to hold the head in place according to the manufacturer's specifications and rotation procedures.


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