Technical Support

What is MLS?

MLS stands for Multi-Layer Steel. MLS head gaskets are comprised of three or five layers of stainless spring steel. The outer layers are an embossed Viton coated stainless steel providing a superior seal with excellent rebound characteristics and are corrosive resistant. MLS head gaskets reduce bore distortion and withstand extreme cylinder pressures. The MLS design is also used in a superior line of exhaust manifold/header gaskets.

Can MLS head gaskets be used with motors setup with o-rings or receiver grooves around the cylinder bores?

No. MLS head gaskets require smooth, flat and true head and deck surfaces to seal. Most of the time with o-ring setups the wire and groove fall where our gasket’s combustion seal is located; therefore, the wire will hold the gasket and not allow proper compression while the receiver grooves allow combustion gases to escape.

What surface finish is required to us an MLS head gasket?

A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design.

What head bolt/stud torque do you recommend when using an MLS gasket?

When using MLS head gaskets always refer to the manufacturer of the fastener to determine accurate torque values. Appropriate torque is critical when installing new gaskets of any kind.

Why does Cometic recommend MLS gaskets to be installed dry?

Cometic Multi-Layer Steel (MLS) head gaskets go on dry because they are coated with a sealant. Each MLS head gasket is coated with a .001" thick Viton rubber that is bonded to the outer stainless steel layers. Adding an additional sealer can hinder the performance of an MLS head gasket.

Can I order head gaskets with a different thickness and/or bore size than you have in your catalog?

Yes. Call Cometic with the engine type or Cometic standard part number (search online or in our catalog) along with the bore size and thickness you would prefer and we will create your custom gasket. (800-752-9850 or 440-354-0777)

Does Cometic offer more than just head gaskets?

Absolutely! Cometic has the capabilities to make every gasket and seal needed to overhaul nearly any type of engine. We offer Rubber Molded Valve Cover Gaskets, intake, exhaust, timing cover, oil pan, rear main seals, valve stem seals, carburetor gaskets, and much more!

What is EST?

EST = Extreme Sealing Technology. EST Harley-Davidson® gasket kits contain: MLS head gaskets, steel viton coated base gaskets, Viton valve stem seals, AFM material (instead of paper), race style exhaust gaskets and one piece rocker box base gaskets. The race style exhaust gaskets will not fray into the port; while the one piece rocker box base gaskets are made from a single layer .020” embossed Viton coated steel. Because of the hi-tech components EST kits are more expensive than standard kits but provide the best seal in the business.