Don't want to screw up the thinking on this subject aj, so lets try to make it completely clear. The copper powder in the compound does help transfer the heat, but these materials are most definitly sealers. They "seal" tiny imperfections such as nicks, scratches or machine tool marks. Most of the sealing compounds without metallic fillers such as Permatex #1,#2 or High Tack are also good to about 500° so I would guess that the carriers in the copper sealers are probably quite similar to the non-metallic compounds. The powdered copper also works as an anti-seize between similar metals when assembling threaded fasteners and connections but it’s compounded primarily as a sealer, not a lubricant. Since I mentioned the anti-seize properties I might mention that the old standby, Locktite Anti-Seize with the aluminum powder is primarily a lubricant and not designed for use as a sealer.
Like Pete already pointed out the copper head compounds also allows the surfaces to move a little when installing and torquing down the head and over the life of the engine as it goes thru its heating and cooling cycles.
The absolute best composite head gaskets in my opinion are the ones that are sheathed in copper because of the heat transfer and the ability of the soft copper to conform to minor imperfections, but I haven’t seen one of those in years. All of the ones in the kits now days are sheathed in steel which doesn’t transfer heat all that well and really isn’t the best material for a metal to metal seal, hence, all the more reason to use the Copper bearing Sealers.
Denny Graham
Sandwich, IL
Last edited by Denny Graham; 05/16/2010 12:17 PM.
