Originally posted by HouseofSpeed
Many sets of shims on TTAs and TRs WITHOUT RTV and no failures.
If you are lifting heads...its not the gasket. Look first to the surface prep of both block and head....then look to tuning. Head gaskets go because of an improper tune more often than not.
You NEVER use any sealer on a head gasket....think about it, that gasket (steel shim or composite with fire ring) is designed to withstand cylinder pressure, heat, and distortion....do you really think that RTV will be of any value in that environment? Even the high temp stuff is not rated for the temperatures seen by the head gasket during combustion. Moreover, if the gasket can't seal the cylinder....how will the RTV?
I think that the "silicon" head gasket idea surfaced way back in the day and was never questioned.....but you will never see a professional engine builder use RTV on a head gasket.