Head gasket

In MLS gaskets, multiple thin layers of cold-rolled steel are coated with a very thin layer of elastomeric material. The elastomer "micro-seals" the surface imperfections in the metal, and resists gases, oils, coolants, and high combustion temperatures.

In MLS gaskets, multiple thin layers of cold-rolled steel are coated with a very thin layer of elastomeric material. The elastomer "micro-seals" the surface imperfections in the metal, and resists gases, oils, coolants, and high combustion temperatures.

====Copper head gaskets====

====Copper head gaskets====

To accomplish combustion sealing with standard copper head gaskets, grooves are machined into the block or the head outside of the combustion sealing area to a width that will retain a stainless wire by friction resistance (usually .039" to .040" wide), the depth of the groove is determined by subtracting the desired protrusion (height) of the installed o-ring from the wire diameter. Stainless steel wire (most often .041" diameter) is then seated into the groove by tapping with a soft faced hammer or other interface tool such as plastic or wood (hard faced hammers can cause dents which create combustion leakage paths). It is advisable to begin and end the o-ring nearest a bolt location to take full sealing advantage of increased loading near the bolt upon the joint in the o-ring. Although copper is a relatively soft material, there is a limit to which it can be displaced by an o-ring. Generally speaking, this limit is about 25% of the gasket thickness. For instance, with a 0.032" thick gasket, you would want to limit the height of the o-ring to about 0.008" above the head or deck surface. For an .043" thick head gasket which is the most common thickness, set the o-ring protrusion at 0.010", for an .050" thick gasket about .012", for an 0.062" thick gasket about 0.015" and so forth. If the groove is cut into the head for the wire, a "receiver groove" can be machined into the block. If the groove is cut into the block deck for the wire, then a receiver groove can be machined into the head surface. When the head is bolted to the block, the wire pushes some of the copper up into the receiver groove and makes a very effective seal. However most street / strip applications do not require receiver grooves, receiver grooves are only required on the most extreme racing appliactions. You'll also need a good sealer around the water passages (K&W Copper Coat is easy to use and easy to find). Copper head gaskets can be re-used several times, simply use a solvent such as brake cleaner to remove any sealant and inspect the area of the gaskets around the combustion seal to insure that there is no 'carbon tracking' which will appear as a shadow on the head gaskets, this is evidence of combustion leaking. If combustion leakage has occured, the gasket(s) must be replaced.

To accomplish combustion sealing with standard copper head gaskets, grooves are machined into the block or the head outside of the combustion sealing area to a width that will retain a stainless wire by friction resistance (usually .039" to .040" wide), the depth of the groove is determined by subtracting the desired protrusion (height) of the installed o-ring from the wire diameter. Stainless steel wire (most often .041" diameter) is then seated into the groove by tapping with a soft faced hammer or other interface tool such as plastic or wood (hard faced hammers can cause dents which create combustion leakage paths). It is advisable to begin and end the o-ring nearest a bolt location to take full sealing advantage of increased loading near the bolt upon the joint in the o-ring. Although copper is a relatively soft material, there is a limit to which it can be displaced by an o-ring. Generally speaking, this limit is about 25% of the gasket thickness. For instance, with a 0.032" thick gasket, you would want to limit the height of the o-ring to about 0.008" above the head or deck surface. For an .043" thick head gasket which is the most common thickness, set the o-ring protrusion at 0.010", for an .050" thick gasket about .012", for an 0.062" thick gasket about 0.015" and so forth. If the groove is cut into the head for the wire, a "receiver groove" can be machined into the block. If the groove is cut into the block deck for the wire, then a receiver groove can be machined into the head surface. When the head is bolted to the block, the wire pushes some of the copper up into the receiver groove and makes a very effective seal. However most street / strip applications do not require receiver grooves, receiver grooves are only required on the most extreme racing appliactions. You'll also need a good sealer around the water passages (K&W Copper Coat is easy to use and easy to find). Copper head gaskets can be re-used several times, simply use a solvent such as brake cleaner to remove any sealant and inspect the area of the gaskets around the combustion seal to insure that there is no 'carbon tracking' which will appear as a shadow on the head gaskets, this is evidence of combustion leaking. If combustion leakage has occured, the gasket(s) must be replaced.

=====Modern copper head gaskets=====

=====Modern copper head gaskets=====

Sealant use may be required when retrofitting MLS head gaskets to engines which were not originally produced with MLS head gaskets, or when using MLS head gaskets on engines that have not been properly prepared. For proper coolant and oil sealing, MLS head gaskets require surface finishes of 30 RA (Roughness Average) or finer, this is because the elastomeric coating on the sealing surfaces of MLS head gaskets is approximately .001" thick which is too thin to seal leak paths in the peaks and valleys of rougher (RA30+) finishes.

Sealant use may be required when retrofitting MLS head gaskets to engines which were not originally produced with MLS head gaskets, or when using MLS head gaskets on engines that have not been properly prepared. For proper coolant and oil sealing, MLS head gaskets require surface finishes of 30 RA (Roughness Average) or finer, this is because the elastomeric coating on the sealing surfaces of MLS head gaskets is approximately .001" thick which is too thin to seal leak paths in the peaks and valleys of rougher (RA30+) finishes.

Steel shim head gaskets are exactly what the name implies, simply a thin sheet of embossed steel with no sealers applied. Steel shim gaskets rely on the combination of increased localized pressure from the embossment (stamped ridges) much like MLS head gaskets, with the addition of a user applied sealant to insure liquid tight operation.

Steel shim head gaskets are exactly what the name implies, simply a thin sheet of embossed steel with no sealers applied. Steel shim gaskets rely on the combination of increased localized pressure from the embossment (stamped ridges) much like MLS head gaskets, with the addition of a user applied sealant to insure liquid tight operation.

===Aluminum cylinder heads===

===Aluminum cylinder heads===