I saw on the silicone head gasket where they say they will not work on a Z head. Never have seen why. Why? Dan
I can't even get them to seal on an iron head, much less an aluminum one.
Well, first off, they don't work or at least not for long, so that part is true enough. I suspect that the thermal expansion/contraction of the aluminum head against the cast iron block is the reason. The repeated relative movement must wear away at the sili gasket.
The silicone is just bead like silicone sealed to the steel core of the gasket. Instructions say don't add additional copper coat or other gasket sealer.
Note the red lines, that is only the place where the silicon lays on the gasket faces. Not too tacky
High compression heads need copper gaskets coated with copper coat sealer.
High compression heads need copper sandwich gaskets coated with copper coat sealer. And be sure to seat (torque) the center line head bolts first and work out and around the perimeter of the cylinder head, the center is where the gasket is most thin at the combustion chambers.
You can see no red silicon around the combustion chamber areas on that silicone high price head gasket.
Here is a busted head gasket off a high compression head, note the finger pointing at where the gasket blew out, right where it is most thin in width.
Good advice and the copper gaskets can be used over in a pinch! If you have ever torn down a flathead v8 with composition gaskets, you would never use anything except copper or steel and it coated with copper coat.
Yes Jim, I had success one time using a gasket again for the third time. Was in a pinch but it worked until the next tear down. Lots of copper coat and proper torquing.
I ordered a silicone gasket just after I bought my car for a spare to have on hand & lately I discovered I have a Z head....bugger
I thought I read where the silicone gasket was not recommended by the folks who make the Z head?
Being new to the game in March I didn't realise I had a Z head on my car until after my first order of spares. Never mind it will still get me home on a run if I get caught.