Thin head gaskets???

Welcome to the forum.

The thin gaskets require very straight machine work with no surface imperfections.

A lot of people won't get seal, because they don't sequence them in stages. Factory calls for two sequences in order on the bolts, the thin gaskets call for three. Break the torque up in three sequences and you'll be glad you did.

I ran a pair with no machine work. One sealed, one didn't.

Found one head at one spot .007" out from square, shaved both heads .010" New gaskets, sequenced 3 times, no leaks under pressure test on the radiator cap.