What does a head gasket squash to?

[Nick Lettington]

Can anyone confirm the thickness of a head gasket when squished up tight?

As mentioned in a previous post or two, I have an aluminium head in poor condition that may benefit from something like a decompression plate bonded to the face... if I use aluminium and omit the head gasket, it might be a better job... provided an aluminium gasket will pass muster... two birds, one stone.

[JonE]

why don't you just try it Nick? If the cost of getting an aluminium head gasket substitute is going to be reasonable.
https://www.ba7c.org/technicalArticles/c...atios.html this mentions some gasket thicknesses.

Advice is going to be thin on the ground where uncertainty and risk are involved, as it perhaps goes against common economic sense. But be creative and find a solution!

I'm currently all at sea with materials and differential expansions. The consideration of sticky goo and metal plates, or blocks, or crankcases - they are seemingly all going to result in failure over time. Likewise silicon sheet, eventually it is going to let the seep through. So we go round in circles as the head gaskets seemingly don't seem to have the characteristics that the old asbestos material needed for longevity. What ARE the characteristics that are seemingly missing?

[Nick Lettington]

Excellent Jon thanks. All I need now is the original thickness of a Speedex head...

[Ian Williams]

Nick, to my mind you are looking for the answer in a way that is unlikely to be accurate. I suggest that you measure the volume of the combustion chambers and then calculate the CR, with that information you will then be able to work out exactly what thickness gasket you need for the CR you desire.