I tryed this on a spare head i had laying around last night but i used my hand and it really did wear some metal off but ill tell ya it took loads of time and then i set it on my cylinder without the head gasket to see if it was uneven but it was perfect, ill upload some pics later![]()
A thin smear of high viscosity oil on the surface, place on glass and observe the underside. Low spots, the oil will not touch the glass.